A Brief Course in Chemistry and Warfare SIDNEY J. FRENCH, Colgate University, Hamilton, New York
HE NEED for technically trained workers in the The following rather abbreviated description of the field of explosives is urgent today. Many institu- course is offered, together with a limited b i b l i ~ ' ~ a ~ h ~ , tions are now training such workers. This training is in the hope that it may be helpful to others planning necessarily narrowly specialized, however, and is often such work. Since the course was of an experimental given to personnel having little understanding of the nature no attempt was made to cover all possible applications or to exhaust all references. fundamental processes involved. If time permitted, it would seem advisable to give The principal topics covered in the ten lectures were such workers a brief orientation course in their fields as follows: Introduction to the chemistry of explosives; gun. before plunging them into spedalized work. Such orientation, however, need not be limited to the techpowder. nical workers in the field of explosives; it might well 2. Nitroglycerinandnitrocelluloseexplosives. 3. Nitroaromatic explosives. be given to many young men planning to enter the armed services. A little knowledrre of the 4. Primary . . explosives or detonators; classification of expIOS1"eS. are using they are handling and the Processes 5. ~h~ synthesis of ammonia and its significance. might well make them more intelligent operators in this 6. Smokes and incendiaries. mighty struggle. To know, for example, that T N T ' 7. Poison gases, historical. 8. Poison gases, classification. can be melted, poured, sawed, drilled, or even fired through with a rifle bullet without explodmg might be of considerable comfort to many men of the armed Topic 1started with simpledefinitionsof terms suchas forces. To know also that wet guncotton is safe guncotton, but that it can be fired with dry guncotton explosion, implosion, explosive materials, the distinction between explosives which burn and produce explosions might be of considerable interest to many a sailor. In addition to some knowledge of explosives, there only in closed places and those which explode in the are numerous other applications of chemistry to war- open. The products of typical explosions were briefly fare which i t would be helpful for every officer to know. considered. Demonstrations included the explosion of nitrogen True, army manuals give much of the essential information needed in condensed form for men in particular triiodide, of potassium and bromine, of hydrogen and branches of the service, but there is no general or back- oxygen. Small mixtures of potassium chlorate and ground material suitable for all officer candidates; phosphorus, of potassium chlorate and sulfur, and of nor is there apt to be time for such material in the short potassium nitrate and sulfur were exploded on an anvil. Next the principal elements found in explosives were period permitted for officer training. The colleges, obviously, can be of considerable assis- considered together with the reason for their imtance in this respect by giving to as many students as portance in such compounds or mixtures. The elements possible such orientation material before these young thus covered included nitrogen, oxygen, carbon, hydromen begin officer training. The material need not be of gen, phosphorus, sulfur, chlorine, aluminum, lead, and highly specialized nature; it can easily be placed a t the mercury. Emphasis was placed on nitrogen as the key freshman level, capable of being grasped by any boy element in most modem explosives. Greek fire, the ancestor of black gunpowder, was inwho has had some slight contact with chemistry. It would seem that as far as the liberal arts college troduced briefly before considering the importance of is concerned its greatest contribution to the war effort the discovery of the explosive nature of black gunpowin the field of chemistry might be the presentation of der. Davis1 lists this discovery as one of three major just such orientation material. In this way, boys (and causes for the breakup of the Middle Ages. The other girls) could be prepared for intelligent participation in two were the invention of the printing press and the technical chemical fields connected with the war or for discovery of America. Whether we agree or not, it is intelligent understanding of the chemicals they may certain that the discovery of the explosive power of black gunpowder radically altered the nature of war come in contact with in war itself. With this point of view in mind, i t was decided to and engineering. The great difficultiesencountered in finding sufficient organize and present a series of ten lectures on "Chemistry in War" a t Colgate University during the past amounts of potassium nitrate for the gunpowder insummer. The lectures were given as a part of the course dustry is amply attested in the history of many wars, in general chemistry but were opened (without credit) including our own Revolutionary War. The opening to all others interested who had had any elementary T A W S -chemistry , of powder and euplosives." John Wiley course in either chemistry or physical science survey. and Sans, New York. 1941, p. 28. 33
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of the Stassfurt mines in Germany provided the potassium, and finally the discovery of the vast Chilean beds of sodium nitrate furnished the other scarce ingredient. Modern methods of making black powder were considered briefly. In Topic 2 several of the more important tests for explosives were explained. These included the Trauzel block test, the small lead block test, the falling weight test, the Dautriche test for speed of propagation of an explosion, the meaning of the term brissance, and the M U N Oeffect. ~ The general methods for preparing nitric esters were then considered, followed by a brief discussion of the preparation and properties of ethylene glycoldinitrate and the glycerol dinitrates. The discovery of the explosive properties of glycerol trinitrate (nitroglycerin) marks the h t important advance in the development of explosives after the introduction of black powder. The interesting story of this discovery and its exploitation by Alfred Nobel is worth spending some minutes on. Other explosives of this general class which were discussed briefly included penthrite (pentaerythritoltetranitrate), nitromannitol (mannitol hexanitrate), nitrostarch, and nitrated sugars. Nitrocellulose (guncotton) comes in for more detailed consideration, which includes its discovery and the early effortsto use i t in war, its method of preparation, and its classification into guncotton and pyronitrocellulose depending upon the degree of nitration. The decade 1880-90 marks the second notable advance in the field of explosives. Up to that time, the only successful propellant had been black powder. AU efforts to use guncotton or other explosives for this purpose had failed. When it was discovered, however, that guncotton formed a colloidal solution in acetone and pyronitrocelluloseformed a similar type of solution in a mixture of ether and alcohol, the way was opened for a new and important propellant-smokeless powder. In 1888 Alfred Nobel patented ballistite, a propellant containing nitroglycerin; the British soon followed with cordite. These new propellants came much closer to the ideal of an explosive for this purpose. They could be made to bum slowly and progressively by the use of retarders such as graphite and by the simple expedient of drilling holes through the cylindrical grains to permit burning from the inside out as well as from the outside in. They left no residue, were nearly smokeless and flashless, gave a high muzzle velocity, were non-corrosive and stable toward high barrel temperatures and changes in humidity. With the addition of stabilizers such as diphenylamine and flash reducers such as potassium chloride they came close to meeting the ideal of a propellant powder. Topic 3 covered explosives derived from the cyclic hydrocarbons. Since these are largely classed as high explosives or bursting charges the ideal qualifications for such an explosive were first considered. It should have high brissance, i. e., it should explode rapidly in
contrast with apropellaut; it should yield alargevolume of gas, should contain sufficient oxygen for complete combustion, should be capable of withstanding the shock of the propellant explosion but nevertheless should be easily and completely discharged by detonation a t the proper time. It should be non-corrosive and stable toward storage for long periods of time, toward handling, melting, pouring, cutting, toward high barrel temperatures and changes in humidity. General methods of preparing the nitroaromatic compounds were then considered with brief mention of the several nitrobenzenes. Of any substance yet tried trinitrotoluene comes the closest to the ideal of a high explosive for all-around use. Its extensive use in World War I and its continued extensive use in World War I1 is ample evidence of that. It is a surprisingly stable compound capable of being pierced with a rifle bullet, melted, transported, poured, sawed, and drilled without exploding. On the other hand, i t can be completely and easily detonated by use of the proper detonator charge. It has high brissance, is little affected by moisture, and is non-corrosive. However, i t is deficient in oxygen, yielding some black smoke on exploding. Its fundamental use is as a burstkgcharge, usually mixed with ammonium nitrate. It was introduced as a military explosive by Germany in 1904, but saw its h t important and sustained use in World War I. One of the greatest obstacles to the wider use of T N T in World War I was lack of toluene. This is no longer an obstacle, since toluene can now be synthesized from petroleum fractions. The process of manufacture, the physiological effects on workers in T N T plants, and available production 5gures were considered briefly. Nitronaphthalene and nitroxylene were mentioned in passing. The second important bursting charge of the aromatic class is piaic acid, together with some of its salts. Although picric acid bas a greater-shattering effectthan any commonly used high explosive its use is limited by its corrosive effect on metals and the high sensitivity to shock of some of the picrate salts thus formed. It is, however, a very stable compound when pure, requiring high detonation to explode it. A vivid account of its combustibility is given by Munroe2in his description of a fire in storage sheds a t Sparta, Wisconsin. Ammonium picrate is often used mixed with picric acid as the well-known Explosive D. The French, in particular, made great use of picric acid explosives in World War I. The methods of manufacture and its properties were considered briefly. One of the newer explosives in the aromatic field is tetryl (tetranitroaniline). It is more sensitive than TNT or picric acid and finds its chief use as a booster charge. Because of high cost and because it deteriorates somewhat on standing, it is used only for military purposes. WUNROE, "Burning of 200,000 pounds of piaic acid at Sparta, Wisconsin." Ind. Eng. Chem., 14, 552 (1922).
Hexyl (hexanitrodiphenylamine) is less sensitive than tetryl but more sensitive than TNT or picric acid. It also 6nds its principal use as a booster. The structures of both of these compounds together with their properties were considered briefly. Topic 4 included detonators or primary explosives as well as the classification of explosives. The two detonators considered were fulminate of mercury and lead azide. In the falling-weight test, the fulminate is about sixty times as sensitive as TNT. The trend today seems to be toward the use of more of the lead azide and toward the use of smaller detonator charges and larger booster charges. Methods of preparing the fulminate and the lead azide, together with safe methods of handling and storage were considered. Other detonating and primer charges which were described were nitrogen triiodide, mixtures of potassium chlorate and sulfur, and potasslum chlorate and antimony sulfide. Explosives can be classified somewhat arbitrarily into three major groups: the low explosives or propellants, the high explosives, and the primary explosives.
garded as one of the most important processes ever developed for either peace or war. After a brief mention of the discovery of nitrogen and ammonia, there followed a reconsideration of the important properties of nitrogen, and a discussion of the due prediction of Sir William Crookes, made in the last century, that the world faced eventual starvation without nitrates. Then theearlier attempts to produce fixed nitrogen were considered. As a prelude to the hccessful Haber-Bosch process, the work of Le Chaielier and the principles involved were considered. It is generally conceded today that Germany would have lost World War I within the first year had she not captured sufficient Chilean nitrate in Belgium to tide her over until her Haber plants could come into full operation. In any discussion of the history of wars, the significance of the perfection of this process and the onset of World War I cannot be overlooked. Figures on world production of synthetic ammonia were considered as far as they were available. Ammonium nitrate has been used without casualty by thousands of college freshmen and high-school seniors for making nitrous oxide. Yet, this same comI. Propellants, sometimes called low explosives, are actually self-combustibles. They burn, producing great pressures pound under the proper conditions is one of the best with non-shattering effects. Included among them are: of our modem high explosives. During World War I black powder, smokeless powder, ballistite, cordite, and it was mixed with TNT to give the explosive, amatol. other modifications. Ammonpulver (a mixture of ammon- This contained upward of 20% ammonium nitrate. ium nitrate and carbon) has been used as a propellant. The trend today is toward much higher proportions of 11. High explosives have great brissance, are reasonably stable ammonium n i t r a t e u p to 80%-and toward the use toward shock or &me, and are exploded only by detonaof ammonium nitrate in other mixtures containinc such tion. his group can be subdivided into boosters and bursting materials as wood, flour, carbon, aluminum, etc. charges, the boosters being the more sensitive to shack. Topic 6, covering smokes and incendiaries, conThere is, however, considerable overlapping of the two sidered first some of the physical principles related to groups. 1. Boosters include nitrostarch, nitromannite, nitrated the movement of smoke particles and gas clouds. These principles included the rate of rise, lateral spread, sugars, tetryl, and hexyl. 2. Bursting charges include TNT, guncotton, DNT drag, effect of convection currents, effect of ground and (dinitrotoluene), explosive D, picric acid, penthrite, air temperatures, optimum particle size, Brownian and ammonium nitrate. 111. Primary explosives include detonators and primers. The movement, color and visibility, total screening effect, former explode on shock as do the latter, but the primers humidity, reaction with air and moisture, and wind produce a flash of fire which serves to ignite a larger charge. velocity. 1. Detonators include fulminate of mercury and lead The following table indicates favorable and unazide. favorable conditions for both smoke and gas clouds. 2. Primers include mixtures of potassium chlorate with
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sulfur or antimony sulfide.
To jire a high explosive projectile properly requires two operations-propelling and bursting. In the propelling operation a detonator sets off a primer; this in turn fires an igniter consisting usually of a charge of black powder. The igniter, in turn, fires the charge of smokeless powder. For setting off the bursting charge a fuse is used. This consists of a device containing a detonator and rimer topether with a train of black oowder. the iength of which can be regulated. The trgin, when it has burned to the end, sets off a second detonator which in turn explodes a booster charge. This explosion ensures the complete detonation of the bursting charge. Topic 5 may seem to have little immediate relationship to war hut the synthesis of ammonia must be re-
FAVORABLE
. ... . . ... .... . . ... ... . ... . . . . ..
CONDITIONS
UNPAV0RABI.E CONDITIONS
Sky . .Heavily overcast Clear Time. .Night or early morning 11 A.M. to 4 P.M. Terrain. . . . . .Level fields or water Broken or wooded Ground temperature Colder than air Warmer than air Wind velocity.. . . . .Steady Variable 5-8 m.p.h. for smoke 12 m.p.h. for 0 4 m.o.h. for eas smoke 9 m.p.h. for gas
White smoke is particularly effective. An efficient smoke-oroducer like ~hosohorusfonns its smoke largely out the air with wkch i t combines. One pound of phosphorus reacts with oxygen and moisture to produce 3.16 pounds of phosphoric acid smoke. In general, phosphorus is the most effective screening agent, but its use is limited by its cost, its sensitivity to spontaneous combustion, and the difficulty of producing the smoke with great rapidity.
of
Screening agents considered were: titanium tetrachloride (FM), sulfur trioxide and chlorsulfonic acid (FS), HC mixture (a mixture of hexachlorethane and powdered zinc), and white phosphorus (WP). A brief history of early incendiaries included the use of Greek fire, burning pitch and sulfur, flaming arrows, red-hot cannon balls, and war rockets (1807 to 1813). With the advent of World War I the use of incendiaries had almost disappeared. White phosphorus used both as a screen and incendiary hand bomb found some use but produced no important results. The advent of the airplane as an important weapon of war has brought the incendiary weapon hack into war with a vengeance. It is claimed that the electron bomb (the thermit magnesium-cased bomb) had been developed by the Germans before the close of World War I, but was not used for fear that peace terms would be harsher. It is undoubtedly one of the most important new weapons introduced into World War 11. Yet it has not accomplished what some German experts apparently hoped that i t would. This bomb was considered in some detail, together with methods of protection and extinguishing magnesium fires. The British "calling cards" used early in World War I1 were sheets of guncotton soaked in a solution of phosphorus in carbon disuliide. They were dropped wet, and when they dried, the finely divided phosphorus took fire and fired the guncotton. Other incendiary weapons discussed b r i d y included incendiary pencils, the "Molotov cocktail," and the "breadbasket." The next two topics were concerned with the socalled poison gases. The first of these two lectures was largely historical in nature, covering early uses of stink bombs, suffocating fumes, the proposal to use sulfur dioxide in the Crimean War, the first cloud-gas attack in World War I, and the later developments in the use of gases in that war. The second lecture dealt with the classification of gases from tactical and physiological points of view, protection against gases, possible new tactical methods of using gases, and new gases, together with reasons why gas has, as yet, found no significant use in World War 11. Because so much has been written and said on this subject already, further details are unnecessary here. Topic 9 was devoted to our chemical resources. The first part of the lecture was devoted to the historical development of German and American chemical industry and the effect of World War I on both. Charts and statistics were used to show the rapid growth of the American chemical industry as well as the comparative growth in other countries. The most striking fact which comes out of such studies is that both the United States and Russia have jumped into leading positions in science. In the second part of the lecture, the most recent reports from Chemical and Engineering News were used to indicate which materials were of a critically essential
nature, which were necessary but not so critically limited, and which were available in slightly larger quantities for use as substitutes. It is very illuminating to compare, for example; the two reports appearing in the March 25 issue and the July 25 issue and to note the number of materials which have moved from the more to the less abundant categories. In fact, the only metals left in the unrestricted group by the report of July 25 were indium, osmium, and silver. Reasons were pointed out for the placing of a number of metals and chemicals in the critical group. Sources of some of the more critical ones, their use in war, and other possible sources and methods of preparation were considered. Among the metals discussed were aluminum, magnesium, chromium, tungsten, manganese, tin, nickel, and steel. The last topic covered the two most strategic materials of this war-gasoline and rubber. Statistics on world production of petroleum for 1941 were presented. At that time the United States, Great Britain, and Russia controlled 94% of the world's output. The importance of Russia's petroleum, constituting nearly 11% of the world's output, was discussed. Germany's sources from petroleum, synthetic processes, and substitutes, were considered as well as her probable needs. Substitutes used in Europe include high- and low-pressure gas, benzene, shale oil, alcohol, wood and coal gas, garbage gas, and electrical propulsion. There followed a discussion of the preparation of high-octane aviation fuel, its significancein the war, and general methods of preparation. Statistics on rubber production were then presented, followed by a brief history of synthetic substitutes. A number of these including buna-S, buna-N, thiokol, and butyl rubber, were described, as well as their general methods of manufacture. Since the great struggle between the proponents of alcohol on the one hand and petroleum on the other, as the basis for making buna rubbers, was raging a t the time, some space was devoted to the apparent relative merits of the two. At each lecture, an attempt was made to have either experimental demonstrations or illustrative displays. For example, the properties of picric acid and ammonium nitrate under varying conditions can be demonstrated. Sniff sets, gas masks, and gas warden's equipment enliven the lectures on gases. The screening and incendiary properties of phosphorus are easily demonstrated, as is the thermit reaction and the combustible nature of magnesium. Cotton can be nitrated or some guncotton used to demonstrate its properties. Ammonia can be oxidized to nitric oxide with a platinum catalyst. Charts and board displays of statistical material help to put across important information. Samples of various synthetic elastomers are of considerable interest. Perhaps the best indication of the success of the
is that it attracted a considerable number of outsiders, both students and faculty. One f a c u l t y member, a professor of fine arts whose particular interest is architecture, came f o r the first few lectures on explosives because of his interest in their effect on course
but he buildines. He never had a course in chemistrv. 2. remain& through the last lecture. The success of this initial venture w a r r a n t s a repet i t i o n in an improved f o r m , and it is expected that the series of lectureswill be repeated from time to time as long as there is a need f o r such material.
BIBLIOGRAPHY
Books DAVIS, "Chemistry of powder and explosives," John Wiley and Sons, New York, 1941. WACHTEL, "Chemical warfare," The Chemical Publishing Company, New York, 1942. FRIESAND WEST,"Chemical warfare," McGraw-Hill Book Company, New York, 1921. M A R S E ~ L"Explosives," , Blakiston Company, Philadelphia. 1915, (Trans. by SYMMES),"Nitroglycerin and nitroglycerin NAO~M explosives," The Williams and Wilkins Company, Philadelphia (1928). TEORPEAND WHITELEY," D i c t i o n a ~of applied chemistry," (Fourth ed.), Volumes I-V, Longmans. Green and Campany, New York, 193741. HAYNESAND HAWSER,"Rationed rubber." Alfred A. Knopf. NewYork. 1942. The "Detection and identification of war gases," Chemical Publishing Company, New York, 1940. Civilian Defense Council of the College of the City of New York, "Handbook of civilian protection." Whittelsey House, New York, 1942.
Manuals "Protection against gas," Office of Civilian Defense, 1941. "Explosives and demolitions," F hf 5-25, war ~ ~ ~ 1941. "Military explosives," T M 9-2900. War Department. 1940. "Military chemistry and chemical agents," T M 3-215, war Department. "The gas mask." T M 3-205. War Department.
Periodicals
I .
HICKEY,"War gas identification sets," J. CBM. EDWC.,19,360 (1942). BELAND, "Chemical warfare," ibid., 19,402 (1942). Bnescm, "Nerve gas on tap," ibid., 19,402 (1942). FRENCH, "Poison gas in tomarraw's war." The Octegon, 25, 108 (1942). Nitrogen: CURTIS,"Nitrogen fixation," J. CEEM.EDWC..19, 161 (1942). Woo~wnno,"Significance of ammonia in national defense," Chem. and Met. Eng., 48, 117 (1941). 48, 120 (1941). FALK,"Ammonium nitrate in Gemany," $a,, Chemical Industry and War: "Facts and figures of American chemical industry," Chem. and Met. Eng., 49,73 (1942). WEIDLEIN,"Chemistry in national defense," Ind. Eng. Chrm., N m s Ed., 19,453 (1941). CONANT,"Chemists and the national defense." Ind. Eng. Chem.. News Ed.. 19, 1237 (1941). "An American of ~apanesechemical industry," Editorial, Chem. and Met. Eng., 49, 116 (1942). "Chemistry, industry and the national defense program" (a symposium), Chem. Industries, 48, 165,300,436 (1941). Metals: WILLIAMS, ~ ~ "Ourt manganese ~ ~supply," ~ ibid., t 48,418 , (1941). "More aluminum for national defense," Cham. and Met. Eng., 48, 106 (1941). KIR='ATRTCK. "Magnesium by the Hansgirg process," iEd., 48, 91 (1941). GONZER, I I U L I ~"Metals and alloys in defense," Chem. Ind.. 49, 30
,."..,.
GRANT,"Magnesium in national defense,'' {bid., 48,712 (1941). KIRKPATRICK, "Magnesium from sea water." Chem. a d Mct. Eng., 48, 72 (1941). PANNELL, "HOW Europe produces its magnesium." ibid.. 48, 78 (1941). "The history of magnesium," Ind.Eng. Chem.,News Ed., 19,993 (1941).
Explosives: CAIRNS, M~ndusbialand military J. cxEM. Eouc., 19,109 (1942). HARD,., -producing smokeless powder by 1942 methods," Chem. and Met. Eng., 49, 76-9, 110 (1942). B ~ f l l "Making ~: explosives for World War 11," ibid ', 48, 76 Rubber: (IY41).
STAFF."Making smokeless powder a t Radford," ibid., 48,103 (1941). KIRKPATRICK, "From farmlands t o T N T and munitions works,"ibid.. 48,125 (1941). KIRKPATRICK, "Midwest builds biggest powder plant." d i d . , 48, 72 (1941). Chemical Warfare: BRADLEY, "Chemical detection of war gases for civilian defense," Chemical and Engineering N m s , 20, 893 (1942) (see bibliography accompanying). PORTER, "The Chemical Warfare Service in national defense, ibid., 19, 1025 (1941).
June, lW2. "Elastomers in the nation's war program," Chem. Industries, SO, 22 (1942). COE, "Present status of rubber chemicals and reclaimed rubber," Ind. Eng. Chem., 33, 1347 (1941). FINGER, "Rubber for defense," I d . Eng. Chem., 33, 1335 (1941). See also 1339. 1343. 602 (1941). EGLOFF,"Modern motor fuels," J. CHEM. EDWC., 18, 582 (1941). EOLOPFAND VANARSDELL, "Substitute fuels as a war economy." Chemical and Engineering News, 20, 649 (1942).
