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CHAPTER VII - DYNAMITE AND OTHER HIGH EXPLOSIVES

Invention of Dynamite
Dynamite and the fulminate blasting cap both resulted from Alfred Nobel’s effort to make nitroglycerin more safe 
and more convenient to use.[l] Having discovered that nitroglycerin is exploded by the explosion of a small 
firecracker-like device filled with black powder, he tried the effect of mixing the two materials, and in 1863 was 
granted a patent[2] which covered the use of a liquid explosive, such as nitroglycerin or methyl or ethyl nitrate, in 
mixture with gunpowder in order to increase the effectiveness of the latter. The amount of the liquid was limited by 
the requirement that the mixtures should be dry and granular in character. The explosives were supposed to be 
actuated by fire, like black powder, but the liquid tended to slow down the rate of burning, and they were not 
notably successful. The same patent also covered the possibility of substituting a part of the saltpeter by 
nitroglycerin. Because this substance is insoluble in water and non-hygroscopic, it acts as a protective covering for 
the salt and makes the use of sodium nitrate possible in these mixtures.

Nobel’s next patent,[3] granted in 1864, related to improvements in the manufacture of nitroglycerin and to the 
exploding of it by heating or by means of a detonating charge. He continued his experiments and in 1867 was 
granted a patent[4] for an explosive prepared by mixing nitroglycerin with a suitable non-explosive, porous 
absorbent such as charcoal or siliceous earth. The resulting material was much less sensitive to shock than 
nitroglycerin. It was known as dynamite, and was manufactured and sold also under the name of Nobel’s Safety 
Powder. The absorbent which was finally chosen as being most satisfactory was diatomaceous earth or kieselguhr 
(guhr or fuller’s earth). Nobel believed that dynamite could be exploded by a spark or by fire if it was confined 
closely, but preferred to explode it under all conditions by means of a special exploder or cap containing a strong 
charge of mercury fulminate, crimped tightly to the end of the fuse in order that it might detonate more strongly. He 
stated that the form of the cap might be varied greatly but that its action depended upon the sudden development 
of an intense pressure or shock.

	1 For an account of Nobel and his inventions see de Mosenthal, Jour. Soc. Chem. Ind., 443 (1899).
	2 Brit. Pat. 2359 (1863).
	3 Brit. Pat. 1813 (1864).
	4 Brit. Pat. 1345 (1867).

FIGURE 83. [Portrait of Alfred Nobel] 
Alfred Nobel (1833-1896). First manufactured and used nitroglycerin commercially, 1863; invented dynamite and the 
fulminate blasting cap, 1867; straight dynamite, 1869; blasting gelatin and gelatin dynamite, 1875; and ballistite, 1888. He 
left the major part of his large fortune for the endowment of prizes, now known as the Nobel Prizes, for notable achievements 
in physics, in chemistry, in physiology and medicine, in literature, and in the promotion of peace.


Dynamite with an inactive base (guhr dynamite) is not manufactured commercially in this country. Small quantities 
are used for experimental purposes where a standard of comparison is needed in studies on the strength of 
various explosives.

The next important event in the development of these explosives was Nobel’s invention of dynamite with an active 
base,[5] an explosive in which the nitroglycerin was absorbed by a mixture of materials which were themselves not 
explosive separately, such as potassium, sodium, or ammonium nitrate mixed with wood meal, charcoal, rosin, 
sugar, or starch. The nitroglycerin formed a thin coating upon the particles of the solid materials, and caused them 
to explode if a fulminate cap was used. The patent suggested a mixture of barium nitrate 70 parts, rosin or charcoal
10, and nitroglycerin 20, with or without the addition of sulfur, as an example of the invention. Nitroglycerin alone 
was evidently not enough to prevent the deliquescence of sodium and ammonium nitrate in these mixtures, for a 
later patent[6] of Nobel claimed the addition of small amounts of paraffin, ozokerite, stearine, naphthalene, or of 
any similar substance which is solid at ordinary temperatures and is of a fatty nature, as a coating for the particles
to prevent the absorption of moisture by the explosive and the resulting danger from the exudation of nitroglycerin.

Dynamite with an active base is manufactured and used extensively in this country and in Canada and Mexico. It is 
known as straight dynamite, or simply as dynamite, presumably because its entire substance contributes to the 
energy of its explosion. The standard 40% straight dynamite which is used in comparative tests at the U. S. Bureau 
of Mines contains[7] nitroglycerin 40%, sodium nitrate 44%, calcium carbonate (anti-acid) 1%, and wood pulp 15%. 
Since the time when this standard was adopted, the usage of the term “straight” has altered somewhat in 
consequence of changes in American manufacturing practice, with the result that this standard material is now 
better designated as 40% straight nitroglycerin (straight) dynamite. This name distinguishes it from 40% l.f. or 40% 
low-freezing (straight) dynamite which contains, instead of straight nitroglycerin, a mixture of nitric esters produced 
by nitrating a mixture of glycerin and glycol or of glycerin and sugar. Practically all active-base dynamites now 
manufactured in the United States, whether straight or ammonia or gelatin, are of this l.f. variety. American straight 
dynamites contain from 20 to 60% of mixed nitric esters absorbed on wood pulp and mixed with enough sodium or 
potassium nitrate to maintain the oxygen balance and to take care of the oxidation of part or occasionally of all the
wood pulp.

	5 Brit. Pat. 442 (1869).
	6 Brit. Pat. 1570 (1873).
	7 C. A. Taylor and W. H. Rinkenbach, “Explosives, Their Materials, Constitution, and Analysis,” U. S. BUR. Mines Bull. 219, 
	Washington, 1923, p, 133.

Judson powder is a special, low-grade dynamite in which 5 to 15% of nitroglycerin is used as a coating on a 
granular dope made by mixing ground coal with sodium nitrate and sulfur, warming the materials together until the 
sulfur is melted, forming into grains which harden on cooling and are screened for size. It is intermediate in power 
between black powder and ordinary dynamite and is used principally for moving earth and soft rock in railroad work.

Nobel’s inventions of blasting gelatin and gelatin dynamite are both covered by the same patent.[8] Seven or 8% 
of collodion cotton dissolved in nitroglycerin converted it to a stiff jelly which was suitable for use as a powerful high 
explosive. Solvents, such as acetone, ether-alcohol, and nitrobenzene, facilitated the incorporation of the two 
substances in the cold, but Nobel reported that collodion cotton dissolved readily in nitroglycerin without additional 
solvent if the nitroglycerin was warmed gently on the water bath. A cheaper explosive of less power could be made 
by mixing the gelatinized nitroglycerin with black powder or with mixtures composed of an oxidizing agent, such as a 
nitrate or chlorate, and a combustible material, such as coal dust, sulfur, sawdust, sugar, starch, or rosin. A typical 
gelatin dynamite consists of nitroglycerin 62.5%, collodion cotton 2.5%, saltpeter 27.0%, and wood meal 8%. A 
softer jelly is used for making gelatin dynamite than is suitable for use by itself as a blasting gelatin, and somewhat 
less collodion is used in proportion to the amount of nitroglycerin.

All straight nitroglycerin explosives can be frozen. Straight dynamite when frozen becomes less sensitive to shock 
and to initiation, but blasting gelatin becomes slightly more sensitive. When the explosives are afterwards thawed, 
the nitroglycerin shows a tendency to exude.

	8 Brit. Pat. 4179 (1875).

Invention of Ammonium Nitrate Explosives
In 1867 two Swedish chemists, C. J. Ohlsson and J. H. Norrbin, patented an explosive, called ammoniakkrut, which 
consisted of ammonium nitrate either alone or in mixture with charcoal, sawdust, naphthalene, picric acid, 
nitroglycerin, or nitrobenzene. Theoretical calculations had shown that large quantities of heat and gas were given 
off by the explosions of these mixtures. The proportions of the materials were selected in such manner that all the 
carbon should be converted- to carbon dioxide and all the hydrogen to water. Some of these explosives were 
difficult to ignite and to initiate, but the trouble was remedied by including some nitroglycerin in their compositions 
and by firing them with fulminate detonators. They were used to some extent in Sweden. Nobel purchased the 
invention from his fellow-countrymen early in the 1870’s, and soon afterwards took out another patent[9] in 
connection with it, but still found that the hygroscopicity of the ammonium nitrate created real difficulty. He was not 
able to deal satisfactorily with the trouble until after the invention of gelatin dynamite. In present manufacturing 
practice in this country the tendency of the ammonium nitrate to take up water is counteracted by coating the 
particles with water-repelling substances, oils, or metallic soaps.

	9 The above-cited Brit. Pat. 1570 (1873).

In 1879 Nobel took out a Swedish patent for extra-dynamite (ammon-gelatin-dynamit), one example of which was a 
fortified gelatin dynamite consisting of nitroglycerin 71%, collodion 4%, charcoal 2%, and ammonium nitrate 23%. 
Another contained much less nitroglycerin, namely, 25%, along with collodion 1%, charcoal 12%, and ammonium 
nitrate 62%, and was crumbly and plastic between the fingers rather than clearly gelatinous.

In these explosives, and in the ammonium nitrate permissible explosives which contain still less nitroglycerin, it is 
supposed that the nitroglycerin or the nitroglycerin jelly, which coats the particles of ammonium nitrate, carries the 
explosive impulse originating in the detonator, that this causes the ammonium nitrate to decompose explosively to 
produce nitrogen and water and oxygen, the last named of which enters into a further explosive reaction with the 
charcoal or other combustible material. Other explosive liquids or solids, such as liquid or solid DNT, TNT, or TNX, 
nitroglycol, nitrostarch, or nitrocellulose, may be used to sensitize the ammonium nitrate and to make the mixture
more easily detonated by a blasting cap. Non-explosive combustible materials, such as rosin, coal, sulfur, cereal 
meal, and paraffin, also work as sensitizers for ammonium nitrate, and a different hypothesis is required to explain 
their action.

Guhr Dynamite
Guhr dynamite is used rather widely in Europe. It is not hygroscopic. Liquid water however, brought into contact 
with it, is absorbed by the kieselguhr and displaces the nitroglycerin which separates in the form of an oily liquid. 
The nitroglycerin thus set free in a wet bore hole might easily seep away into a fissure in the rock where it would 
later be exploded accidentally by a drill or by the blow of a pick. Water does not cause the separation of 
nitroglycerin from blasting gelatin or gelatin dynamite. It tends to dissolve the soluble salts which are present in 
straight dynamite and to liberate in the liquid state any nitroglycerin with which they may be coated.

Guhr dynamite, made from 1 part of kieselguhr and 3 parts of nitroglycerin, is not exploded by a blow of wood upon 
wood, but is exploded by a blow of iron or other metal upon iron. In the drop test it is exploded by the fall of a 
1-kilogram weight through 12 to 15 cm., or by the fall of a 2-kilogram weight through 7 cm. The frozen material is 
less sensitive: a drop of more than 1 meter of the kilogram weight or of at least 20 cm. of the 2-kilogram weight is 
necessary to explode it. Frozen or unfrozen it is exploded in a paper cartridge by the impact of a bullet from a 
military rifle. A small sample will burn quietly in the open, but will explode if it is lighted within a confined space. A 
cartridge explodes if heated on a metal plate.

The velocity of detonation of guhr dynamite varies with the density of loading and with the diameter of the charge, 
but does not reach values equal to the maxima under best conditions for nitroglycerin and blasting gelatin. 
Velocities of 6650 to 6800 meters per second, at a density of loading of 1.50 (the highest which is practical) have 
been reported. Naoum,[10] working with charges in an iron pipe 34 mm. in internal diameter and at a density of 
loading of 1.30, found for nitroglycerin guhr dynamite a velocity of detonation of 5650 meters per second, and, 
under the same conditions, for nitroglycol guhr dynamite one of 6000 meters per second.

	10 Phokion Naofim, “Nitroglycerine and Nitroglycerine Explosives,” trans E. M. Symmes, Baltimore, The Williams and 
	Wilkins Company, 1928 p. 277.

FIGURE 84. [Photo of explosives being placed on a plate] Determination of the Velocity of Detonation of Dynamite
by the Dautriche Method. (Courtesy Hercules Powder Company,) Compare Figure 9, page 17.

Dynamites, like guhr dynamite and straight dynamite, which contain nitroglycerin in the subdivided but liquid state 
communicate explosion from cartridge to cartridge more readily, and in general are more easy to initiate, than 
blasting gelatin and gelatin dynamite in which no liquid nitroglycerin is present. A cartridge of guhr dynamite 30 mm. 
in diameter will propagate its explosion through a distance of 30 cm. to a similar cartridge.

Straight Dynamite
Straight dynamite containing 60% or less of mixed nitric esters - but not more because of the danger of exudation - 
is used extensively in the United States, but has found little favor in Europe. It is made simply by mixing the 
explosive oil with the absorbent materials; the resulting loose, moist-appearing or greasy mass, from which oil ought 
not to exude under gentle pressure, is put up in cartridges or cylinders wrapped in paraffined paper and dipped 
into melted paraffin wax to seal them against moisture.

FIGURE 85. [Dynamite Manufacture.] (Courtesy Hercules Powder Company.) Rubbing the dry ingredients of dynamite 
through a screen into the bowl of a mixing machine.

The strength of straight nitroglycerin dynamite is expressed by the per cent of nitroglycerin which it contains. Thus, 
“40% straight nitroglycerin dynamite” contains 40% of nitroglycerin, but “40% ammonia dynamite,” “40% gelatin 
dynamite,” etc., whatever their compositions may be, are supposed to have the same strength or explosive force as 
40% straight nitroglycerine dynamite. Munroe and Hall[11] in 1915 reported for typical straight nitroglycerin 
dynamites the compositions which are shown in the following table. 

	11 Charles E. Munroe and Clarence Hall, “A Primer on Explosives for Metal Miners and Quarrymen,” U. S. Bur. Mines Bull. 80, 
	Washington, 1915, p. 22.

	STRENGTH
	15%	20%	25%	30%	35%	40%	45%	50%	55%	60%
Nitroglycerin	15	20	25	30	35	40	45	50	55	60
Combustible material	20	19	18	17	16	15	14	14	16	16
Sodium nitrate	64	60	56	52	48	44	40	35	29	23
Calcium or magnesium carbonate	1	1	1	1	1	1	1	1	1	1

FIGURE 86. [Dynamite Manufacture.] (Courtesy Hercules Powder Company.) Hoppers underneath the mixing machine, 
showing the buggies which carry the mixed dynamite to the packing machines.

Although these dynamites are not now manufactured commercially in the United States, their explosive properties, 
studied intensively at the U. S. Bureau of Mines and reported as a matter of interest, do not differ greatly from those
of the l.f. dynamites by which they have been superseded in common use. The combustible material stated to be
used in these compositions consists of a mixture of wood pulp, flour, and brimstone for the grades below 40% 
strength, wood pulp alone for the 40% and stronger. In commercial practice the dope sometimes contains coarse 
combustible material, like rice hulls, sawdust, or bran, which makes the explosive more bulky and has the effect of 
reducing the velocity of detonation. Tests at the U. S. Bureau of Mines on standard straight dynamites in cartridges 
1-1/4 inches in diameter showed for the 30% grade a velocity of detonation of 4548 meters per second, for the 40%
grade 4688 meters per second, and for the 60% grade 6246 meters per second. The 40% dynamite was exploded 
in one case out of three by an 11-cm. drop of a 2-kilogram weight, in no case out of five by a 10-cm. drop. 
Cartridges 1-1/4 inches in diameter and 8 inches long transmitted explosion from one to another through a distance
of 16 inches once in two trials, but not through a distance of 17 inches in three trials. The 40% dynamite gave a
small lead block compression of 16.0 mm., and an expansion (average of three) in the Trauzl test of 278 cc.[12]

FIGURE 87. [Dynamite Manufacture.] (Courtesy Hercules Powder Company.) Dumping the mixed dynamite onto the 
conveyor belt which raises it to the hopper of the semi-automatic packing machine.

	12 Clarence Hall, W. 0. Snelling, and S.,P. Howell, “Investigations of Explosives Used in Coal Mines,” U. S. Bur. Mines Bull. 15, 
	Washington, 1912, pp. 171, 173.

Munroe and Hall[13] also reported the following compositions for typical ordinary and low-freezing ammonia 
dynamites, the combustible material in each case being a mixture of wood pulp, flour, and brimstone. Low-freezing 
dynamites at present in use in this country contain nitroglycol or nitrosugar instead of the above-mentioned 
nitrosubstitution compounds. In Europe dinitrochlorohydrin, tetranitrodiglycerin, and other nitric esters are used.

Strength	| -------- Ordinary -------- |					| ----- Low-Freezing ----- |
	30%	35%	40%	50%	60%	30%	35%	40%	50%	60%
Nitroglycerin	15	20	22	27	35	13	17	17	21	27
Nitrosubstitution compounds	--	--	--	--	--	3	4	4	5	6
Ammonium nitrate	15	15	20	25	30	15	15	20	25	30
Sodium nitrate	51	48	42	36	24	53	49	45	36	27
Combustible material	18	16	15	11	10	15	14	13	12	9
Calcium carbonate or zinc oxide	1	1	1	1	1	1	1	1	1	1

Three of the standard French ammonia dynamites, according to Naoum,[14] have the compositions and explosive 
properties listed below.

Nitroglycerin		40	20	22
Ammonium nitrate		45	75	75
Sodium nitrate		5	- -	- -
Wood or cereal meal		10	5	- -
Charcoal		- -	- -	3
Lead block expansion		400.0 cc.	335.0 cc.	330.0 cc.
Lead block crushing		22.0 mm.	15.5 mm.	16.0 mm.
Density		1.38	120	1.33

Taylor and Rinkenbach[15] report typical analyses of American ammonium nitrate dynamite (I below) and 
ammonium nitrate sodium nitrate dynamite (II below). These formulas really represent ammonium nitrate permissible 
explosives, very close in their compositions to Monobel (III below) which is permissible in this country for USC in coal 
mints. Naoum[16] reports that this Monobel (density about 1.15) gives a lead block expansion of about 350 cc. and 
a lead block crushing of 12 mm. He states that Monobel belongs to the class of typical ammonium nitrate explosives
rather than to the dynamites, and points out that no specific effect can be ascribed to the 10% nitroglycerin which it 
contains, for an explosive containing only a small quantity, say 4%, of nitroglycerin, or none at all, will give 
essentially the same performance. But the ammonium nitrate explosive with no nitroglycerin in it is safer to handle 
and more difficult to detonate.

	13 Op. cit., p. 23.	14 Op. cit.., p. 285.		15 op. cit., pp, 136, 138.		16 op. cit., p; 286.
	17 The carbonaceous combustible material contains 0.40% grease or oil which was added to the ammonium nitrate to 
	counteract its hygroscopicity. Note that the figures in the first two columns of the table represent results of analyses; 
	those in the third column represent the formula according to which the explosive is mixed.

		I	II	II
Nitroglycerin		9.50	9.50	10.0
Ammonium nitrate		79.45	69.25	80.0
Sodium nitrate		- -	10.20	- -
Carbonaceous combustible material		9.75	9.65	- -
Wood meal		- -	- -	10.0
Anti-acid		0.40	0.50	- -
Moisture		0.90	0.90	- -

FIGURE 88. [Dynamite Manufacture.] (Courtesy Hercules Powder Company.) Cartridges of dynamite as they come from 
the semi-automatic packing machine.

Blasting Gelatin
Blasting gelatin exists as a yellowish, translucent, elastic mass of density about 1.63. Strong pressure does not 
cause nitroglycerin to exude from it. Its surface is rendered milky by long contact with water, but its explosive 
strength is unaffected. It is less sensitive to shock, blows, and friction than nitroglycerin, guhr dynamite, and 
straight dynamite, for its elasticity enables it more readily to absorb the force of a blow, and a thin layer explodes 
under a  hammer more easily than a thick one. Blasting gelatin freezes with difficulty. When frozen, it loses its 
elasticity and flexibility, and becomes a hard, white mass. Unlike guhr dynamite and straight dynamite, it is more 
sensitive to shock when frozen than when in the soft and unfrozen state. Unlike nitroglycerin, blasting gelatin takes 
fire easily from a flame or from the spark of a fuse. Its combustion is rapid and violent, and is accompanied by a 
hissing sound. If a large quantity is burning, the combustion is likely to become an explosion, and the same result is
likely to follow if even a small quantity of the frozen material is set on fire.

Pulverulent explosives .or explosive mixtures are easier to initiate and propagate detonation for a greater distance 
than liquid explosives, especially viscous ones, and these are easier to detonate and propagate more readily than 
colloids. The stiffer the colloid the more difficult it becomes to initiate, until, with increasingly large proportions of 
nitrocellulose in the nitroglycerin gel, tough, horny colloids are formed, like ballistite and cordite, which in sizable 
aggregates can be detonated only with difficulty. Blasting gelatin is more difficult to detonate than any of the forms
of dynamite in which the nitroglycerin exists in the liquid state. Naoum[18] reports that a freshly prepared blasting 
gelatin made from 93 parts of nitroglycerin and 7 parts of collodion cotton is exploded by a No. 1 (the weakest) 
blasting cap and propagates detonation even in 25-mm. cartridges across a gap of about 10 mm. A blasting gelatin 
containing 9% of collodion cotton requires a No. 4 blasting cap to make it explode and propagates its explosion to 
an adjacent cartridge only when initiated by a No. 6 blasting cap.

Blasting gelatin and gelatin dynamite on keeping become less sensitive to detonation, and, after long storage in a 
warm climate, may even become incapable of being detonated. The effect has been thought to be due to the small 
air bubbles which make newly prepared blasting gelatin appear practically white but which disappear when the 
material is kept in storage and becomes translucent and yellowish. But this cannot be the whole cause of the effect, 
for the colloid becomes stiffer after keeping. The loss of sensitivity is accompanied by a rapid dropping off in the 
velocity of detonation and in the brisance. According to Naoum,[19] blasting gelatin containing 7% collodion cotton 
when newly prepared gave a lead block expansion of 600 cc., after 2 days 580 cc., and one containing 9% 
collodion gave when freshly made an expansion of 580 cc., after 2 days 545 cc.

Blasting gelatin under the most favorable conditions has a velocity of detonation of about 8000 meters per second. 
In iron pipes it attains this velocity only if its cross section exceeds 30 mm. in diameter, and it attains it only at a 
certain distance away from the point of initiation, so that in the Dautriche method where short lengths are used 
lower values are generally obtained. In tubes of 20-25 mm. diameter, and with samples of a sensitivity reduced 
either by storage or by an increased toughness of the colloid, values as low as 2000-2500 meters per second have 
been observed.

	18 Op. cit., p. 316.	19 Op. cit., p, 322.

Gelatin Dynamite
Blasting gelatin is not used very widely in the United States; the somewhat less powerful gelatin dynamite, or simply 
gelatin as it is called, is much more popular. Gelatin dynamite is essentially a straight dynamite in which a gel is 
used instead of the liquid nitroglycerin or l.f. mixture of nitric esters. It is a plastic mass which can be kneaded and 
shaped. The gel contains between 2 and 5.4% collodion cotton, and is not tough and really elastic like blasting 
gelatin. Correspondingly it is initiated more easily and has a higher velocity of detonation and better propagation.
The gel is prepared by mixing the nitroglycerin and collodion cotton, allowing to stand at 40-45C. for some hours or
over night, and then incorporating mechanically with the dope materials which have been previously mixed 
together. Munroe and Hall[20] in 1915 gave the compositions listed below as typical of gelatin dynamites offered 
for sale at that time in this country. Instead of straight nitroglycerin, l.f. mixtures of nitric esters are now used.

			STRENGTH
			30%	35%	40%	50%	55%	60%	70%
	Nitroglycerin		23.0	28.0	33.0	42.0	46.0	50.0	60.0
	Nitrocellulose		0.7	0.9	1.0	1.5	1.7	1.9	2.4
	Sodium nitrate		62.3	58.1	52.0	45.5	42.3	38.1	29.6
	Combustible material [21]		13.0	12.0	13.0	10.0	9.0	9.0	7.0
	Calcium carbonate		1.0	1.0	1.0	1.0	1.0	1.0	1.0

The three standard explosives which are used in Great Britain are called respectively blasting gelatin, gelatin 
dynamite, and Gelignite. Gelignite, let us note, is a variety of gelatin dynamite as the latter term is used in this 
country. It is the most widely used of the three and may indeed be regarded as the standard explosive.

	20 op. cit., p. 23.
	21 Wood pulp was used in the 60% and 70% grades. Flour, wood pulp, and, in some examples, rosin and brimstone were used 
	in the other grades.

		BLASTING	GELATIN
		GELATIN	DYNAMITE	GELIGNITZ
	Nitroglycerin	92	75	60
	Collodion cotton	8	5	4
	Wood meal	- -	5	8
	Potassium nitrate	- -	15	28

The gelatin dynamites most widely used in Germany contain about 65 parts of gelatinized nitroglycerin and about 
35 parts of dope or absorbent material. The dope for an explosive for domestic use consists of 76.9% sodium 
nitrate, 22.6% wood meal, and 0.5% chalk, and for one for export of 80% potassium nitrate, 19.5% wood meal, and 
0.5% chalk. A weaker Gelignite II and certain high-strength gelatin dynamites, as tabulated below, are also 
manufactured for export.

		GELIGNITE	HIGH-STRENGTH GELATIN DYNAMITE
		II	80%	81%	75%
	Nitroglycerin	47.5	75.	75.6	70.4
	Collodion cotton	2.5	5	5.2	4.6
	Potassium nitrate	37.5	15	15.2	19.3
	Wood meal with chalk	2.5	5	3.8	5.7
	Rye meal	9.0	- -	- -	- -

The gelatin dynamites manufactured in Belgium are called Forcites. The reported compositions of several of them 
are tabulated below. Forcite extra is an ammonia gelatin dynamite.

		Forcite Composition:
		Extra	Superior	Super	No. 1	1-P	No. 2	2-P
	Nitroglycerin	64	64	64	49	49	36	36
	Collodion cotton	3.5	3	3	2	2	3	2
	Sodium nitrate	- -	24	- -	36	- -	35	- -
	Potassium nitrate	- -	- -	23	- -	37	- -	46
	Ammonium nitrate	25	- -	- -	- -	- -	- -	- -
	Wood meal	6.5	8	9	13	11	11	- -
	Bran	- -	- -	- -	- -	- -	14	15
	Magnesium carbonate	1	1	1	1	1	1	1

In France gelatin dynamites are known by the names indicated in the following table where the reported 
compositions of several of them are tabulated.

Permissible Explosives
The atmosphere of coal mines frequently contains enough methane (fire damp) to make it explode from the flame of
a black powder or dynamite blast. Dust also produces an explosive atmosphere, and it may happen, if dust is not 
already present, that one blast will stir up clouds of dust which the next blast will cause to explode. Accidents from 
this cause became more and more frequent as the industrial importance of coal increased during the nineteenth 
century and as the mines were dug deeper and contained more fire damp, until finally the various nations which 
were producers of coal appointed commissions to study and develop means of preventing them. The first of these 
was appointed in France in 1877, the British commission in 1879, the Prussian commission in 1881, and the Belgian
and Austrian commissions at later dates. The Pittsburgh testing station of the U. S. Geological Survey was officially 
opened and regular work was commenced there on December 3, 1908, with the result that the first American list of 
explosives permissible for use in gaseous and dusty coal mines was issued May 15, 1909. On July 1, 1909, the 
station was taken over by the U. S. Bureau of Mines[22] which, since January 1, 1918, has conducted its tests at 
the Explosives Experiment Station at Bruceton, not far from Pittsburgh, in Pennsylvania.

Explosives which are approved for use in gaseous arid dusty coal mines are known in this country as permissible 
explosives, in England as permitted explosives, and are to be distinguished from authorized explosives which 
conform to certain conditions with respect to safety in handling, in transport, etc. Explosives which are safe for use 
in coal mines are known in France as explosifs antigrisouteux, in Belgium as explosifs S. G. P. (se’quritc’, grisou, 
poussikre), in Germany as schkgwettersichere Sprengstoffe while the adjective handhnbungssichere is applied to those
which are safe in handling. Both kinds, permissible and authorized, are safety explosives, explosifs de surete,
Sicherheitssprengstoffe.

A mixture of air and methane is explosive if the methane content lies between 5 and 14%. A mixture which contains 
9.5% of methane, in which the oxygen exactly suffices for complete combustion, is the one which explodes most 
violently, propagates the explosion most easily, and produces the highest temperature. This mixture ignites at about 
650 to 700°. Since explosives in general produce temperatures which are considerably above 1000 degree 
explosive mixtures of methane and air would always be exploded by them if it were not for the circumstance, 
discovered by Mallard and Le Chatelier,[23] that there is a certain delay or period of induction before the gaseous 
mixture actually explodes. At 650° this amounts to about 10 seconds, at 1000° to about 1 second, 
and at 2200° there is no appreciable delay and the explosion is presumed to follow instantaneously after 
the application of this temperature however momentary. Mallard and Le Chatelier concluded that an explosive 
having a temperature of explosion of 2200° or higher would invariably ignite fire damp. The French 
commission which was studying these questions at first decided that the essential characteristic of a permissible 
explosive should be that its calculated temperature of explosion should be not greater than 2200°, and later 
designated a temperature of 1500° as the maximum for explosives permissible in coal seams and 1900
degrees for those intended to be used in the accompanying rock.

	22 A few of the interesting and important publications of the U. S. Bureau of Mines are listed in the footnote, Vol. I, pp, 22-23,
	23 Ann. Min., 181 11, 274 (1887)

The flame which is produced by the explosion of a brisant explosive is of extremely short duration, and its high 
temperature continues only for a small fraction of a second, for the hot gases by expanding and by doing work 
immediately commence to cool themselves. If they are produced in the first place at a temperature below that of the
instantaneous inflammation of fire damp, they may be cooled to such an extent that they are not sufficiently warm 
for a sufficiently long time to ignite fire damp at all. Black powder, burning slowly, always ignites explosive gas 
mixtures. But any high explosive may be made safe for use in gaseous mines by the addition to it of materials which 
reduce the initial temperature of the products of its explosion. Or, in cases where this initial temperature is not too 
high, the same safety may be secured by limiting the size of the charge and by firing the shot in a well-tamped bore 
hole under such conditions that the gases are obliged to do more mechanical work and are cooled the more in 
consequence.

Permissible explosives may be divided into two principal classes: (1) those which are and (2) those which are not 
based upon a high explosive which is cool in itself, such as ammonium nitrate, or guanidine nitrate, or 
nitroguanidine. The second class may be subdivided further, according to composition, into as many classes as 
there are varieties in the compositions of high explosives, or it may be subdivided, irrespective of composition,
according to the means which are used to reduce the explosion temperature. Thus, an explosive containing 
nitroglycerin, nitrostarch, chlorate or perchlorate, or tetranitronaphthalene, or an explosive which is essentially 
black powder, may have its temperature of explosion reduced by reason of the fact that (a) it contains an excess of 
carbonaceous material, (b) it contains water physically or chemically held in the mixture, or (c) it contains volatile 
salts or substances which are decomposed by heat. Ammonium nitrate may also be used as a means of lowering 
the temperature of explosion, and thus defines another subdivision (d) which corresponds to an overlapping of the 
two principal classes, (a) and (b).

Ammonium nitrate, although it is often not regarded as an explosive, may nevertheless be exploded by a suitable 
initiator. On complete detonation it decomposes in accordance with the equation

						2NH4N03  → 4H2O + 2N2 + 02

but the effect of feeble initiation is to cause decomposition in another manner with the production of oxides of 
nitrogen. By using a booster of 20-30 grams of Bellite (an explosive consisting of a mixture of ammonium nitrate and
dinitrobenzene) and a detonator containing 1 gram of mercury fulminate, Lobry de Bruyn[24] succeeded in 
detonating 180 grams of ammonium nitrate compressed in a 8 cm. shell. The shell was broken into many fragments.
A detonator containing 3 grams of mercury fulminate, used without the booster of Bellite, produced only incomplete
detonation. Lheure[25] secured complete detonation of cartridges of ammonium nitrate[26] loaded in bore holes in 
rock by means of a trinitrotoluene detonating fuse which passed completely through them.

	24 Rec. true. chim., 10, 127 (1891).		25 Ann. Min., 1101 12, 169 (1907).
	26 On the explosibility of ammonium nitrate, see also Munroe, Chem. Met. Eng., 26, 535 (1922) ; Cook, ibid., 31, 231 (1924) ; 
	Sherrick, Armt, Ordnance, 4, 237, 329 (1924).

The sensitiveness of ammonium nitrate to initiation is increased by the addition to it of explosive substances, such 
as nitroglycerin, nitrocellulose, or aromatic nitro compounds, or of non-explosive combustible materials, such as 
rosin, sulfur, charcoal, flour, sugar, oil, or paraffin. Substances of the latter class react with the oxygen which the 
ammonium nitrate would otherwise liberate; they produce additional gas and heat, and increase both the power of 
the explosive and the temperature of its explosion. Pure ammonium nitrate has a temperature of explosion of about 
1120 to 1130°. Ammonium nitrate explosives permissible in the United States generally produce 
instantaneous temperatures between 1500 and 2000°.

Among the first permissible explosives developed in France were certain ones of the Belgian. Favier type which 
contained no nitroglycerin and consisted essentially of ammonium nitrate, sometimes with other nitrates, along with 
a combustible material such as naphthalene or nitrated naphthalene or other aromatic nitro compounds. These 
explosives have remained the favorites in France for use in coal mines. The method of manufacture is simple. The 
materials are ground together in a wheel mill, and the mass is broken up, sifted, and packed in paraffined paper 
cartridges. The compositions of the mixtures are those which calculations show to give the desired temperatures of 
explosion. Grisounites roches, permissible for use in rock, have temperatures of explosion between 1500 and 
1900 degrees; Grisounites couches, for use in coal, below 1500°. Several typical compositions are listed 
below.

The French also have permissible explosives containing both ammonium nitrate and nitroglycerin (gelatinized), with
and without saltpeter. These are called Grisou-dynamites or Grisoutines.

The effect of ammonium nitrate in lowering the temperature of explosion of nitroglycerin mixtures is nicely illustrated 
by the data of Naoum[27] who reports that guhr dynamite (75% actual nitroglycerin) gives a temperature of 2940°, 
a mixture of equal amounts of guhr dynamite and ammonium nitrate 2090°, and a mixture of 1 part of guhr dynamite 
and 4 of ammonium nitrate 1468°.

	27.op. cit., p. 403.

In ammonium nitrate explosives in which the ingredients are not intimately incorporated as they are in the Favier 
explosives, but in which the granular particles retain their individual form, the velocity of detonation may be 
regulated by the size of the nitrate grains. A relatively slow explosive for producing lump coal is made with coarse-
grained ammonium nitrate, and a faster explosive for the procurement of coking coal is made with fine grained
material.

The first explosives to be listed as permissible by the U. S. Bureau of Mines were certain Monobels and Carbonites, 
and Monobels are still among the most important of American permissibles. Monobels contain about 10% 
nitroglycerin, about 10% carbonaceous material, wood pulp, flour, sawdust, etc., by the physical properties of which 
the characteristics of the explosive are somewhat modified, and about 80% ammonium nitrate of which, however, a 
portion, say 10%, may be substituted by a volatile salt such as sodium chloride.


In Europe the tendency is to use a smaller amount of nitroglycerin, say 4 to 6%, or, as in the Favier explosives, to 
omit it altogether. Ammonium nitrate permissible explosives which contain nitroglycerin may be divided broadly into 
two principal classes, those of low ammonium nitrate content in which the oxygen is balanced rather accurately 
against the carbonaceous material and which are cooled by the inclusion of salts, and those which have a high 
ammonium nitrate content but whose temperature of explosion is low because of an incomplete utilization of the 
oxygen by a relatively small amount of carbonaceous material. Explosives of the latter class are more popular in 
England and in Germany. Several examples of commercial explosives of each sort are listed in the following table:

		I	II	III	IV	V	VI	VII	VIII
	Ammonium nitrate	52.0	53.0	60.0	61.0	66.0	73.0	78.0	83.0
	Potassium nitrate	21.0	- -	- -	- -	- -	2.8	5.0	7.0
	Sodium nitrate	- -	12.0	5.0	3.0	- -	- -	- -	- -
	Barium nitrate	- -	- -	- -	- -	- -	- -	- -	2.0
	Na or K chloride	- -	- -	21.0	20.5	22.0	15.0	8.0	- -
	Hydrated ammonium oxalate	16.0	19.0	- -	- -	- -	- -	- -	- -
	Ammonium chloride	6.0	- -	- -	- -	- -	- -	- -	- -
	Cereal or wood meal	- -	4.0	4.0	7.5	2.0	1.0	5.0	2.0
	Glycerin	- -	- -	- -	3.0	- -	- -	- -	- -
	Powdered coal	- -	- -	- -	- -	4.0	- -	- -	- -
	Nitrotoluene	- -	- -	6.0	1.0	- -	- -	- -	- -
	Dinitrotoluene	- -	- -	- -	- -	- -	5.0	- -	- -
	Trinitrotoluene	- -	6.0	- -	- -	- -	- -	- -	2.0
	Nitroglycerin	5.0	5.0	4.0	4.0	4.0	3.2	4.0	4.0

The Carbonites which are permissible are straight dynamites whose temperatures of explosion are lowered by the 
excess of carbon which they contain. As a class they merge, through the Ammon-Carbonites, with the class of 
ammonium nitrate explosives. The Carbonites, have the disadvantage that they produce gases which contain 
carbon monoxide, and for that reason have largely given way for use in coal mines to ammonium nitrate 
permissibles which contain an excess of oxygen. Naoum[28] reports the compositions and explosive characteristics 
of four German Carbonites as follows.

	28 Op. cit., p. 401.

		I	II	III	IV
	Nitroglycerin	25.0	25.0	25.0	30.0
	Potassium nitrate	30.5	34.0	- -	- -
	Sodium nitrate	- -	- -	30.5	24.5
	Barium nitrate	4.0	1.0	- -	- -
	Spent tan bark meal	40.0	1.0	- -	- -
	Meal	- -	38.5	39.5	40.5
	Potassium dichromate	- -	- -	5.0	5.0
	Sodium carbonate	0.5	0.5	- -	- -
	Heat of explosion, Cal/kg	576	506	536	602
	Temperature of explosion	1874°	1561°	1666°	1639°
	Velocity of detonation, meters/set	2443	2700	3042	2472
	Lead block expansion	235cc	213cc	240cc	258cc

The salts which are most frequently used in permissible explosives are sodium chloride and potassium chloride, 
both of which are volatile (the potassium chloride more readily so), ammonium chloride and ammonium sulfate, 
which decompose to form gases, and the hydrated salts, alum Al2 (SO4)3 • K2S04 • 24H20 ; ammonium alum 
Al2(SO4)3 • (NH4)2SO4 • 24H20 ; chrome alum Cr2(SO4)3 • K2SO4 • 24H20 ; aluminum sulfate Al2( SO4)3 • 18H20 ;
ammonium oxalate (NH4)2C2O4 • H2O; blue vitriol CuSO4 • 5H2O; borax Na2B4O7 • 10H2O; Epsom salt MgSO4 • 
7H2O;  Glauber’s salt Na2SO4 • 10H2O; and gypsum CaSO4 • 2H2O, all of which give off water, while the ammonium
salts among them yield other volatile products in addition. Hydrated sodium carbonate is not suitable for use 
because it attacks both ammonium nitrate and nitroglycerin.[29]

Sprengel Explosives
Explosives of a new type were introduced in 1871 by Hermann Sprengel, the inventor of the mercury high-vacuum 
pump, who patented[30] a whole series of mining explosives which were prepared by mixing an oxidizing substance 
with a combustible one “in such proportions that their mutual oxidation and de-oxidation should be theoretically 
complete.” The essential novelty of his invention lay in the fact that the materials were mixed just before the 
explosive was used, and the resultant explosive mixture was fired by means of a blasting cap. Among the oxidizing 
agents which he mentioned were potassium chlorate, strong nitric acid, and liquid nitrogen dioxide; among the 
combustible materials nitrobenzene, nitronaphthalene, carbon disulfide, petroleum, and picric acid.[31] Strong nitric 
acid is an inconvenient and unpleasant material to handle. It can eat through the copper capsule of a blasting cap 
and cause the fulminate to explode. Yet several explosives containing it have been patented, Oxonite, for example,
consisting of 58 parts of picric acid and 42 of fuming nitric acid, and Hellhoffite, 28 parts of nitrobenzene and 72 of 
nitric acid. These explosives are about as powerful as 70% dynamite, but are distinctly more sensitive to shock and 
to blows. Hellhoffite was sometimes absorbed on kieselguhr to form a plastic mass, but it still had the disadvantage 
that it was intensely corrosive and attacked paper, wood, and the common metals.

The peculiarities of the explosives recommended by Sprengel so set them apart from all others that they define a 
class; explosives which contain a large proportion of a liquid ingredient and which are mixed in situ immediately 
before use are now known as Sprengel explosives. They have had no success in England, for the reason that the 
mixing of the ingredients has been held to constitute manufacture within the meaning of the Explosives Act of 1875 
and as such could be carried out lawfully only on licensed premises. Sprengel explosives have been used in the 
United States, in France, and in Italy, and were introduced into Siberia and China by American engineers when the 
first railroads were built in those countries. Rack-a-rock, patented by S. R. Divine,[32] is particularly well known 
because it was used for blasting out Hell Gate Channel in New York Harbor. On October 10, 1885, 240,399 pounds 
of it, along with 42,331 pounds of dynamite, was exploded for that purpose in a single blast. It was prepared for use
by adding 21 parts of nitrobenzene to 79 parts of potassium chlorate contained in water-tight copper cartridges.

	29 C. G. Storm, “The Analysis of Permissible Explosives,” U. S. Bur. Mines Bull. 96, Washington, 1916.
	30 Brit. Pats. 921, 2642 (1871).
	31 Sprengel was aware in 1871 that picric acid alone could be detonated by means of fulminate but realized 
	also that more explosive force could be had from it if it were mixed with an oxidizing agent. Picric acid alone
	was evidently not used practically as an explosive until after Turpin in 1886 had proposed it as a bursting 
	charge for shells.
	32 Brit. Pats. 5584, 5596 (1881) ; 1461 (1882) ; 5624, 5625 (1883).

The Promethees, authorized in France under the name of explosifs 0 No. 3, are prepared by dipping cartridges of a 
compressed oxidizing mixture of potassium chlorate 80 to 95% and manganese dioxide 5 to 20% into a liquid 
prepared by mixing nitrobenzene, turpentine, and naphtha in the proportions 50/20/30 or 60/15/25. The most 
serious disadvantage of these explosives was an irregularity of behavior resulting from the circumstance that 
different cartridges absorbed different quantities of the combustible oil, generally between 8 and 13%, and that the 
absorption was uneven and sometimes caused incomplete detonation. Similar explosives are those of Kirsanov, a 
mixture of 90 parts of turpentine and 10 of phenol absorbed by a mixture of 80 parts of potassium chlorate and 20 
of manganese dioxide, and of Fielder, a liquid containing 80 parts of nitrobenzene and 20 of turpentine absorbed 
by a mixture of 70 parts of potassium chlorate and 30 of potassium permanganate. 

The Panclastites, proposed by Turpin in 1881, are made by mixing liquid nitrogen dioxide with such combustible 
liquids as carbon disulfide, nitrobenzene, nitrotoluene, or gasoline. They are very sensitive to shock and must be 
handled with the greatest caution after they have once been mixed. In the first World War the French used certain 
ones of them, under the name of Anilites, in small bombs which were dropped from airplanes for the purpose of 
destroying personnel. The two liquids were enclosed in separate compartments of the bomb, which therefore 
contained no explosive and was safe while the airplane was carrying it. When the bomb was released, a little 
propeller on its nose, actuated by the passage through the air, opened a valve which permitted the two liquids to 
mix in such fashion that the bomb was then filled with a powerful high explosive which was so sensitive that it 
needed no fuze but exploded immediately upon impact with the target.

Liquid Oxygen Explosives
Liquid oxygen explosives were invented in 1895 by Linde who had developed a successful machine for the 
liquefaction of gases. The Oxyliquits, as he called them, prepared by impregnating cartridges of porous combustible 
material with liquid oxygen or liquid air are members of the general. class of Sprengel explosives, and have the 
unusual advantage from the point of view of safety that they rapidly lose their explosiveness as they lose their liquid
oxygen by evaporation. If they have failed to fire in a bore hole, the workmen need have no fear of going into the 
place with a pick or a drill after an hour or so has elapsed.

Liquid oxygen explosives often explode from flame or from the spurt of sparks from a miner’s fuse, and frequently 
need no detonator, or, putting the matter otherwise, some of them are themselves satisfactory detonators. Like 
other detonating explosives, they may explode from shock. Liquid oxygen explosives made from carbonized cork 
and from kieselguhr mixed with petroleum were used in the blasting of the Simplon tunnel in 1899. The explosive 
which results when a cartridge of spongy metallic aluminum absorbs liquid oxygen is of theoretical interest because 
its explosion yields no gas; it yields only solid aluminum oxide and heat, much heat, which causes the extremely 
rapid gasification of the excess of liquid oxygen and it is this which produces the explosive effect. Lampblack is the 
absorbent most commonly used in this country.

Liquid oxygen explosives were at first made up from liquid air more or less self-enriched by standing, the nitrogen 
(b.p. - 195°) evaporating faster than the oxygen (b.p. - 183°) but it was later shown that much better results 
followed from the use of pure liquid oxygen. Rice reports 33 that explosives made from liquid oxygen and an 
absorbent of crude oil on kieselguhr mixed with lampblack or wood pulp and enclosed in a cheesecloth bag within a
corrugated pasteboard insulator were 4 to 12% stronger than 40% straight nitroglycerin dynamite in the standard 
Bureau of Mines test with the ballistic pendulum. They had a velocity of detonation of about 3000 meters per 
second. They caused the ignition of fire damp and produced a flame which lasted for 7.125 milliseconds as 
compared with 0.342 for an average permissible explosive (no permissible producing a flame of more than 1 
millisecond duration). The length of the flame was 2-1/2 times that of the flame of the average permissible. In the 
Trauzl lead block an explosive made up from a liquid air (i.e., a mixture of liquid oxygen and liquid nitrogen) 
containing 33% of oxygen gave no explosion; with 40% oxygen an enlargement of 9 cc.; with 50% 80 cc., with 55% 
147 cc.; and with 98% oxygen an enlargement of 384 cc., about 20% greater than the enlargement produced by
60% straight dynamite. The higher temperatures of explosion of the liquid oxygen explosives cause them to give 
higher results in the Trauzl test than correspond to their actual explosive power.

Liquid oxygen explosives are used in this country for open-cut mining or strip mining, not underground, and are 
generally prepared near the place where they are to be used. The cartridges are commonly left in the “soaking box” 
for 30 minutes, and on occasions have been transported in this box for several miles.

One of the most serious faults of liquid oxygen explosives is the ease with which they inflame and the rapidity with 
which they burn, amounting practically and in the majority of cases to their exploding from fire. Denues[34] has 
found that treatment of the granular carbonaceous absorbent with an aqueous solution of phosphoric acid results 
in an explosive which is non-inflammable by cigarettes, matches, and other igniting agents. Mono and di ammonium 
phosphate, ammonium chloride, and phosphoric acid were found to be suitable for fireproofing the canvas 
wrappers. Liquid oxygen explosives made up from the fireproofed absorbent are still capable of being detonated by 
a blasting cap. Their strength, velocity of detonation, and length of life after impregnation are slightly but not 
significantly shorter than those of explosives made up from ordinary non-fireproofed absorbents containing the 
same amount of moisture.

	33 George S. Rice, “Development of Liquid Oxygen Explosives during the War,” V. S. Bur. Mines Tech. 
	Paper 243, Washington, 1920, pp. 14-16. Also, S. P. Howell, J. W. Paul, and J. L. Sherrick, “Progress of 
	Investigations on Liquid Oxygen Explosives,” V. S. Bnr. Mines Tech. Paper 294, Washington, 1923, pp. 33, 35, 51.
	34 A.R.T. Denues, “Fire Retardant Treatments of Liquid Oxygen Explosives,” U. S. Bur. Mines BUZZ. 429, Washington, 1940.

Chlorate and Perchlorate Explosives
The history of chlorate explosives goes back as far as 1788 when Berthollet attempted to make a new and more 
powerful gunpowder by incorporating in a stamp mill a mixture of potassium chlorate with sulfur and charcoal. He 
used the materials in the proportion 6/1/1. A party had been organized to witness the manufacture, M. and Mme. 
Lavoisier, Berthollet, the Commissaire M. de Chevraud and his daughter, the engineer M. Lefort, and others. The 
mill was started, and the party went away for breakfast. Lefort and Mlle. de Chevraud were the first to return. The 
material exploded, throwing them to a considerable distance and causing such injuries that they both died within a 
few minutes. In 1849 the problem of chlorate gunpowder was again attacked by Augendre who invented a white 
powder made from potassium chlorate 4 parts, cane sugar 1 part, and potassium ferrocyanide 1 part. However, no 
satisfactory propellent powder for use in guns has yet been made from chlorate. Chlorate powders are used in toy 
salutes, maroons, etc., where a sharp explosion accompanied by noise is desired, and chlorate is used in primer 
compositions and in practical high explosives of the Sprengel type (described above) and in the Cheddites and 
Silesia explosives.

Many chlorate mixtures, particularly those which contain sulfur, sulfides, and picric acid, are extremely sensitive to 
blows and to friction. In the Street explosives; later called Cheddites because they were manufactured at Chedde in 
France, the chlorate is phlegmatized by means of castor oil, a substance which appears to have remarkable powers
in this respect. The French Commission des Substances Explosives in 1897 commenced its first investigation of 
these explosives by a study of those which are listed below, and concluded[35] that their sensitivity to shock is less 
than that of No. 1 dynamite (75% guhr dynamite) and that when exploded by a fulminate cap they show a 
considerable brisance which however is less than that of dynamite.

		I	II	III
	Potassium chlorate	75.0	74.6	80.0
	Picronitronaphthalene	20.0	- -	- -
	Nitronaphthalene	- -	5.5	12.6
	Starch	- -	14.9	- -
	Castor oil	5.0	5.0	8.0

Later studies showed that the Cheddites had slightly more force than No. 1 dynamite, although they were markedly 
less brisant because of their lower velocity of detonation. After further experimentation four Cheddites were 
approved for manufacture in France, but the output of the Poudrerie de Vonges where they were made consisted 
principally of Cheddites No. 1 and No. 4.

The Cheddites are manufactured by melting the nitro compounds in the castor oil at 80°, adding little by little the 
pulverized chlorate dried and still warm, and mixing thoroughly. The mixture is emptied out onto a table, and rolled 
to a thin layer which hardens on cooling and breaks up under the roller and is then sifted and screened.

Sodium chlorate contains more oxygen than potassium chlorate, but has the disadvantage of being hygroscopic. 
Neither salt ought to be used in mixtures which contain ammonium nitrate or ammonium perchlorate, for double 
decomposition might occur with the formation of dangerous ammonium chlorate. Potassium chlorate is one of the 
chlorates least soluble in water, potassium perchlorate one of the least soluble of the perchlorates. The latter salt is 
practically insoluble in alcohol. The perchlorates are intrinsically more stable and less reactive than the chlorates, 
and are much safer in contact with combustible substances. Unlike the chlorates they are not decomposed by 
hydrochloric acid, and they do not yield an explosive gas when warmed with concentrated sulfuric acid. The 
perchlorates require a ‘higher temperature for their decomposition than do the corresponding chlorates.

SOLUBILITY: PARTS PER 100 PARTS OF WATER
		KClO3	NaClO3	KClO4	NH4CIO4
	At 0°	3.3	82.	0.7	12.4
	At 100°	56.	204.	18.7	88.2

Mixtures of aromatic nitro compounds with chlorate are dangerously sensitive unless they are phlegmatized with 
castor oil or a similar material, but there are other substances, such as rosin, animal and vegetable oils, and 
petroleum products, which give mixtures which are not unduly sensitive to shock and friction and may be handled 
with reasonable safety. Some of these, such as Pyrodiulyte[36] and the Steelites,[37] were studied by the 
Commission des Substances Explosives. The former consisted of 85 parts of potassium chlorate and 15 of rosin, 2 
parts of alcohol being used during the incorporation. The latter, invented by Everard Steele of Chester, England, 
contained an oxidized rosin (residee in French) which was made by treating a mixture of 90 parts of colophony and 
10 of starch with 42 Be nitric acid. After washing, drying, and powdering, the residee was mixed with powdered
potassium chlorate, moistened with methyl alcohol, warmed, and stirred gently while the alcohol was evaporated. 

		STEELITE	STEELITE	STEELITE	COLLIERY
		No. 3	No. 5	No. 7	STEELITE
	Potassium chlorate	75	83.33	87.50	72.5-75.5
	Residee	25	16.67	12.50	23.5-26.5
	Aluminum	- -	5.00	- -	- -
	Castor oil	- -	- -	- -	0.5-1.0
	Moisture	- -	- -	- -	0-1

Colliery Steelite passed the Woolwich test for safety explosives and was formerly on the British permitted list but 
failed in the Rotherham test. In Germany the Silesia explosives have been used. to some extent. Silesia No. 4 
consists of 80 parts of potassium chlorate and 20 of rosin, and Silesia IV 22, 70 parts of potassium chlorate, 8 of
rosin, and 22 of sodium chloride, is cooled by the addition of the volatile salt and is on the permissible list.

The Sebomites,[38] invented by Eugene Louis, contained animal fat which was solid at ordinary temperature, and 
were inferior to the Cheddites in their ability to transmit detonation. Explosifs P (potasse) and S (soude)[38] and the 
Minelites,[40] containing petroleum hydrocarbons, were studied in considerable detail by Dautriche, some of whose 
results for velocities of detonation are reported in the table on pages 362-363 where they are compared with his 
results for Cheddite 60, fourth formula.[41] His experimental results[42] illustrate very clearly the principle that there
is an optimum density of loading at which the velocity of detonation is greatest and that at higher densities the 
velocity drops and the detonation is incomplete and poorly propagated. The Cheddite 60, fourth formula, when 
ignited burns slowly with a smoky flame. Explosifs P and S and the Minelites burn while the flame of a Bunsen 
burner is played upon them but, in general, go out when the flame is removed. Minelite B, under the designation 
0 No. 6 B, was used by the French during the first World War in grenades and mines. A similar explosive containing 
90 parts of sodium chlorate instead of 90 of potassium chlorate was used in grenades and in trench mortar bombs.

		EXPLOSIFS		MINELITES
		P	S	A	B	C
	Potassium chlorate	90	- -	90	90	89
	Sodium chlorate	- -	89	- -	- -	- -
	Heavy petroleum oil	- -	- -	3	- -	- -
	Vaseline	- -	- -	- -	3	4
	Paraffin	10	11	7	7	5
	Pitch	- -	- -	- -	- -	2

Chlorate explosives which contain aromatic nitro compounds have higher velocities of detonation and are more 
brisant than those whose carbonaceous material is merely combustible. The addition of a small amount of 
nitroglycerin increases the velocity of detonation still farther. Brisant chlorate explosives of this sort were developed 
in Germany during the first World War and were known as Koronit and Albit (Gesteinskoronit, Kohlenkoronit, 
Wetterulbit, etc.). They found considerable use for a time but have now been largely superseded by low-percentage
dynamites and by perchlorate explosives. Two of them, manufactured by the Dynamit A.-G., had according to 
Naoum[43] the compositions. and explosive characteristics which are indicated below. It is interesting that the 
explosive which contained a small amount of nitroglycerin was more brisant, as well as softer and more plastic, and 
less sensitive to shock, to friction, and to initiation than the drier explosive which contained no nitroglycerin. It 
required a No. 3 blasting cap to explode it, but the material which contained no nitroglycerin was exploded by a 
weak No. 1.

	36 Mkm. Poudres, 11, 53 (1901).
	37 Ibid., 15, 181 (1909-1910).
	38 Ibid., 13, 280 (1905-1906) ; 15, 137 (1909-1910).
	39 Ibid., 15, 212 (1909-1910).
	40 Ibid., 16, 224 (1911-1912).
	41 The composition of this explosive was the same as that which is given in the table on page 359 as that of 0 No. 2, 
	formula 60 bis M, or Cheddite No. 4.
	42 In several cases Dautriche reported temperatures, but the velocity of detonation appears to be unaffected by such 
	temperature variations as those between summer and winter.
	43 Op. cit., p. 428.

		GESTEINS-	GESTEINS-
		KORONIT	KORONIT
		T1	T2
	Sodium chlorate	72.0	75.0
	Vegetable meal	1.0-2.0	1.0-2.0
	Di- and trinitrotoluene	20.0	20.0
	Paraffin	3.0-4.0	3.0-4.0
	Nitroglycerin	3.0-4.0	-- --
	Heat of explosion, Cal/kg	1219.0	1241.0
	Temperature of explosion	3265°	3300°
	Velocity of detonation, m./sec	5000.0	4300.0
	Density of cartridge	1.57	1.46
	Lead block expansion	290.0 cc	280.0 cc
	Lead block crushing	20.0mm	19.5mm

During the first World War when Germany needed to conserve as much as possible its material for military 
explosives, blasting explosives made from perchlorate came into extensive use. The Germans had used in their 
trench mortar bombs an explosive, called Perdit, which consisted of a mixture of potassium perchlorate 56%, with 
dinitrobeneene 32% and dinitronaphthalene 12%. After the War, the perchlorate recovered from these bombs and 
that from the reserve  stock came onto the market, and perchlorate explosives, Perchlorit, Perchloratit, Persalit, 
Perkoronit, etc., were used more widely than ever. The sale of these explosives later ceased because the old 
supply of perchlorate became exhausted and the new perchlorate was too high in price. Each of these explosives 
required a No. 3 cap for its initiation. Perchlorate explosives in general are somewhat less sensitive to initiation than 
chlorate explosives. A small amount of nitroglycerin in perchlorate explosives plays ,a significant part in propagating
the explosive wave and is more important in these compositions than it is in ammonium nitrate explosives. Naoum
[44] reports the following particulars concerning two of the Perkoronites.

	44 op. cit., p. 430.

		PERKORONIT A	PERKORONIT B
	Potassium perchlorate	58	59
	Ammonium nitrate	8	10
	Di- and trinitrotoluene, vegetable meal	30	31
	Nitroglycerin	4
	Heat of explosion, Cal/kg.	1170.0	1160.0
	Temperature of explosion	3145.0°	3115.0°
	Velocity of detonation, m./sec.	5000.0	4400.0
	Density of cartridge	1.58	1.52
	Lead block expansion	340.0 cc	330.0 cc
	Lead block crushing	20.0 mm.	18.0 mm.

Potassium perchlorate and ammonium perchlorate permissible explosives, cooled by means of common salt, 
ammonium oxalate, etc., and containing either ammonium nitrate or alkali metal nitrate with or without nitroglycerin, 
are used in England, Belgium, and elsewhere. They possess no novel features beyond the explosives already 
described. Explosives containing ammonium perchlorate yield fumes which contain hydrogen chloride. Potassium 
perchlorate produces potassium chloride.

Early in the history of these explosives the French Commission des Substances Explosives published a report on 
two ammonium perchlorate Cheddites.[45] The manufacture of these explosives, however, was not approved for 
the reason that the use of castor oil for phlegmatizing was found to be unnecessary. Number I took fire easily and 
burned in an 18-mm. copper gutter at a rate of 4.5 mm. per second, and produced a choking white smoke. 
Cheddite 60, for comparison, burned irregularly in the copper gutter, with a smoke which was generally. black, at a 
rate of 0.4-0.5 mm. per second. Number II took fire only with the greatest difficulty, and did not maintain its own 
combustion. The maximum velocities of detonation in zinc tubes 20 mm. in diameter were about 4020 meters per 
second for No. I and about 3360 for No. II.

		I	II
	Ammonium perchlorate	82	56
	Sodium nitrate	- -	30
	Dinitrotoluene	13	15
	Castor oil	5	5

	45 Men. poudres, 14, 206 (1907-1908).

The Commission published in the same report a number of interesting observations on ammonium perchlorate. 
Pieces of cotton cloth dipped into a solution of ammonium perchlorate and dried were found to burn more rapidly 
than when similarly treated with potassium chlorate and less rapidly than when similarly treated with sodium 
chlorate. Ammonium perchlorate inflamed in contact with a hot wire and burned vigorously with the production of 
choking white fumes, but the combustion ceased as soon as the hot wire was removed. Its sensitivity to shock, as
determined by the drop test, was about the same as that of picric acid, but its sensitivity to initiation was distinctly 
less. A 50-cm. drop of a 5-kilogram weight cause-d explosions in about 50% of the trials. A cartridge, 16 cm. long 
and 26 mm. in diameter, was filled with ammonium perchlorate gently tamped into place (density of loading about 
1.10) and was primed with a cartridge of the same diameter containing 25 grams of powdered picric acid (density of 
loading about 0.95) and placed in contact with one end of it. When the picric acid booster was exploded, the
cartridge of perchlorate detonated only for about 20 mm. of its length and produced merely a slight and decreasing 
furrow in the lead plate on which it was resting. When a booster of 75 grams of picric acid was used, the detonation 
was propagated in the perchlorate for 35 mm. The temperature of explosion of ammonium perchlorate was 
calculated to be 1084°.

The French used two ammonium perchlorate explosives during the first World War.

		I	II
	Ammonium perchlorate	86	61.5
	Sodium nitrate	- -	30.0
	Paraffin	14	8.5

The first of these was used in 75-mm. shells, the second in 58-mm. trench mortar bombs.

Hydrazine perchlorate melts at 131-132°, burns tranquilly, and explodes violently from shock.

Guanidine perchlorate is relatively stable to heat and to mechanical shock but possesses extraordinary explosive 
power and sensitivity to initiation. Naoum[46] states that it gives a lead block expansion of about 400 cc. and has a 
velocity of detonation of about 6000 meters per second at a density of loading of 1.15.

	46 Naoum, “Schiess- und Sprengstoffe,” Dresden and Leipzig, 1927, p. 137.

Ammonium Nitrate Military Explosives
The Schneiderite (Explosif S or Sc) which the French used during the first World War in small and medium-size 
high explosive shells, especially in the 75 mm., was made by incorporating 7 parts of ammonium nitrate and 1 of 
dinitronaphthalene in a wheel mill, and was loaded by compression. Other mixtures, made in the same way, were 
used in place of Schneiderite or as a substitute for it.

		NX	NT	NTN	NDNT	N2TN
	Ammonium nitrate	77	70	80	85	50
	Sodium nitrate	- -	- -	- -	- -	30
	Trinitrotoluene	- -	30	- -	5	- -
	Trinitroxylene	23	- -	- -	- -	- -
	Dinitronaphthalene	- -	- -	- -	10	- -
	Trinitronaphthalene	- -	- -	20	- -	20

Amatol, developed by the British during the first World War, is made by mixing granulated ammonium nitrate with 
melted trinitrotoluene, and pouring or extruding the mixture into the shells where it solidifies. The booster cavity is 
afterwards drilled out from the casting. The explosive can be cut with a hand saw. It is insensitive, to friction and is 
less sensitive to initiation and more sensitive to impact than trinitrotoluene. It is hygroscopic, and in the presence of 
moisture attacks copper, brass, and bronze.

Amatol is made up in various proportions of ammonium nitrate to trinitrotoluene, such as 50/50, 60/40, and 80/20. 
The granulated, dried, and sifted ammonium nitrate, warmed to about 90°, is added to melted trinitrotoluene at 
about 90°, and the warm mixture, if 50/50 or 60/40, is ladled into the shells which have been previously warmed 
somewhat in order that solidification may not be too rapid, or, if 80/20, is stemmed or extruded into the shells by 
means of a screw operating within a steel tube. Synthetic ammonium nitrate is preferred for the preparation of
amatol. The pyridine which is generally present in gas liquor and tar liquor ammonia remains in the ammonium 
nitrate which is made from these liquors and causes frothing and the formation of bubbles in the warm amatol-with 
the consequent probability of cavitation in the charge. Thiocyanates which are often present in ammonia from the 
same sources likewise cause frothing, and phenols if present tend to promote exudation.

The velocity of detonation of TNT-ammonium nitrate mixtures decreases regularly with increasing amounts of 
ammonium nitrate, varying from about 6700 meters per second for TNT to about 4500 meters per second for 80/20 
amatol. The greater the proportion of ammonium nitrate the less the brisance and the greater the heaving power of 
the amatol. 50/50 Amatol does not contain oxygen enough for the complete combustion of its trinitrotoluene, and 
gives a smoke which is dark colored but less black than the smoke from straight TNT. 80/20 Amatol is less brisant 
than TNT. It gives an insignificant white smoke. Smoke boxes are usually loaded with 80/20 amatol in order that the
artilleryman may observe the bursting of his shells. The best smoke compositions for this purpose contain a large 
proportion of aluminum and provide smoke by day and a brilliant flash of light by night.

The name of ammonal is applied both to certain blasting explosives which contain aluminum and to military 
explosives, based upon ammonium nitrate, which contain this metal. Military ammonals are brisant and powerful 
explosives which explode with a bright flash. They are hygroscopic, but the flake aluminum which they contain 
behaves somewhat in the manner of the shingles on a roof and helps materially to exclude moisture. At the 
beginning of the first World War the Germans were using in major caliber shells an ammonal having the first of the 
compositions listed below. 

		GERMAN	AMMONAL	FRENCH
		I	II	AMMONAL
	Ammonium nitrate	54	72	86
	Trinitrotoluene	30	12	- -
	Aluminum flakes	16	16	8
	Stearic acid	- -	- -	6

After the War had advanced and TNT had become more scarce, ammonal of the second formula was adopted. The 
French also used ammonal in major caliber shells during the first World War. All three of the above-listed explosives
were loaded by compression. Experiments have been tried with an ammonal containing ammonium thiocyanate; the 
mixture was melted, and loaded by pouring but was found to be unsatisfactory because of its rapid decomposition. 
Ammonal yields a flame which is particularly hot, and consequently gives an unduly high result in the Trauzl lead 
block test.

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