INDUSTRIAL AND ENGINEERING CHEMISTRY
October. 1928
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By-Products of Chemical Warfare' Major General Amos A. Fries CHIEF,CHEXICAI,WARFARE SERVICE,UNITEDSTATESARMY
I
N T H E industrial world by-products play an important
part and their value is well recognized. In the realm of government by-products are little known and receive but scant public attention. Still more remote in the public mind is the idea of valuable peacetime by-products from the military establishment. And yet our manifold national defense activities today are yielding some by-products of considerable commercial value. As a striking example of this useful and but little known contribution to our national progress may be cited the peacetime activities of the Chemical Warfare Service, the youngest and smallest branch of our military establishment. This branch of the Army was born during the World War of stern necessity and was made a part of our permanent military establishment in the posbwar reorganization of the Army in 1920. The chief military purpose of the Chemical Warfare Service is, of course, to protect our Army and country against enemy chemical warfare in any future emergency. To carry out this duty, the Chemical Warfare Service maintains a t its central establishment, Edgewood Arsenal, a small but highly specialized research organization, whose constant study of toxic and poisonous materials has made its members the poison experts of the Government. Consequently, any peacetime problem involving the use of, or protection against, poisonous materials is one which this organization is preeminently qualified to solve. As many such problems are closely related to chemical warfare research, their solution flows directly from the research activities of this service. The following are some of the commercially valuable .peacetime achievements of the Chemical Warfare Service. Protection of Marine Piling
At the request of the National Research Council early in 1923, the Chemical Warfare Service undertook the study of the effectiveness of poisons against marine borers that destroy docks and other water-front structures, to an estimated value of a million dollars annually. Appropriations were made for the work by the Quartermaster Corps, U. S. Army, and the Bureau of Yards and Docks, U. S. Navy. The facilities of the laboratory of the Bureau of Fisheries a t Beaufort, N. C., were made available through the courtesy of the Department of Commerce. The principal types of borer from which protection was desired are the Teredine, the Limnoria, and the Martesia. All of these are found in the waters near Beaufort. A detailed progress report of the investigation was published in the Bulletin of the American Railway Engineering Association of October, 1926. As a result of a test of over one hundred compounds it was found that organic compounds of arsenic, mercury, and copper had the best general toxic value against the various types of marine borers. Of the arsenical tested, those which were either chemical agents of warfare or derivatives of those chemicals were the most effective. A derivative of Lewisite had the highest toxic value against the marine borers of any compound tried. The toxics used in this investigation were investigated and made at Edgewood Arsenal, and toxicity studies were carried out at Beaufort. Before any specific toxicity information was available, test pieces of pine and oak, 1 foot long and 3 inches square, were impregnated with various compounds using either creosote or fuel oil as a vehicle in some standard wood im1
Received June 9, 1928.
pregnation process. In most cases no difficulty was experienced in obtaining a good radial penetration of the impregnant in the wood. These pieces were sheathed on two sides with untreated half-inch pine boards. This enabled the embryo to secure a foothold in the untreated wood and, by the time the impregnated portion was reached, the shipworm was full grown and more resistant to the action of the toxic. These test pieces were installed in sets of three to each compound and a number of those showing no attack have been in place for five seasons. Solutions of the following five compounds in creosote have stopped the borer from passing into the treated portion after having riddled the bait pieces: copper o-nitrobenxoate, mercury benzoate, mercury resinate, mercury stearate, and diphenylaminechloroarsine. Straight creosote impregnations did not stop the borers from passing into the treated portion. Untreated control pieces were completely riddled in less than three months. Pine fence posts, averaging 8 feet long and 6 inches in diameter, were impregnated in the small-scale impregnation plant with some of the mixtures indicated as being most effective. Thirteen sets of ten posts each were installed in the Beaufort Harbor, N. C., during 1924, and it is planned to pull one post of each set per year for inspection, thus insuring at least a tenyear test for this locality. Three sets of posts showed no attack in about three years. These sets were impregnated with straight creosote (present commercial practice) ; diphenylaminechloroarsine (a war gas) in creosote; and diphenylaminechloroarsine in equal parts of oil, oil tar, and water-gas tar. The following conclusions have been drawn from the work: (1) About fifteen compounds show specific toxicity against marine borers of from twenty-five to fifty times that of creosote. (2) Better protection for piling than is afforded by creosote alone may be obtained a t a very slightly increased cost by the addition of a specific toxic to the creosote. (3) At least equal protection to that afforded by creosote may be obtained a t less cost, by the addition of a specific toxic to fuel oil or some other cheap vehicle. (4) Final selection of the best all-rough materials for use depends upon the results of the long-time test pieces now installed. (5) The use of any of these materials will not involve any change in the present commercial methods of impregnation. (6) Little or no increased hazard, either in the impregnation process or in the installation of the piling, results from the use of any of the compounds now being tried in long-time service.
Combating the Boll Weevil The boll weevil annually destroys millions of dollars of grown cotton in our southern states. Many thousands of dollars have been expended by both the states affected and the Federal Government in attempt to stem the ravages of this insect. The Chemical Warfare Service investigation of methods for the control of the boll weevil was started in the late summer of 1924 in accordance with a special appropriation by Congress. The early work consisted mainly in the determination of the relative toxicity of a large number of compounds against the boll weevil itself, using as a standard of comparison commercial calcium arsenate, which up to that time had been found to be the most effective chemical against the weevil. This initial comparison was made using the substances both as dusts and as mixtures with molasses and other suitable solutions in tests in ordinary glass tumblers. Those
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INDUSTRIAL AND ENGINEERING CHEMISTRY
.materials which showed any promise whatsoever were subjected to several additional tumbler tests, and were also c a m fully tested as to their toxicity towards the cotton plant by
Figure 1-Marine Plllnga Showing Rorecdon Afforded by Toric 1mwegnante Left: antreated control piece. (Notedamage done by Limnoda.) pieces tteated with tnRic impregmazits
new material, but in its commercial form is from three to four times as heavy as commercial calcium arsenate, and from 3 to 4 pounds of it are required to cover the same a r a 1 pound of calcium arsenate will cover. Use has been made of the fact that this material is a by-product of the fertilizer indusdry and it has been lightened without loss of its toxic properties, so that it is comparable with calcium arsenate on a pound-pcrpound basis. It h s taken many years to bring calcium amenate up to its present state of mechanical efficiency. This special sodium fluosilicate can be improved. It is too freeflowing and does not stick to the plant so well as calcium arsenate, but i s a quicker weevil-killing agent and it is thought, that it will not be extremely difficult to make the fliiosilicate equal to cunimercial calcium arsenate in adhering qualities without impairing its effectiveness. It has also been fairly conclusively demonstrated that, properly made, a calcium arsenate can contain as low as 20 per rent arsenic and still be as effective as commercial calcirini arsenate. A new and cheap met.hod for the manufacture of this special calcium arsenate has been developed.
Other
preliminary tests on field and greenhouse cobton. Those snhsfances which successfully passed these preliminary tests were set aside for tests in special cages and further tests on a large scale in the field. Over 1000 possible poisons and poisonous mixtures and about 2500 combinations thereof were tried out and more than 250,000 boll weevils were used in these experiments. Largescale field tests were conducted in 1927 at Gainesville, Fla.; Tifton, Ga.; and Summerville, S. C. These teste were under the direct supervision of Chemical Warfare Service pessonnel snd were run in cooperation with the state experiment stations a t these places. The poisons selected for use were special sodium fluosilicate, special barium fluosilicate, and s p e d calcium arsenate (20 per cent arsenic as As&), which m r e run in comparison to commercial calcium arsenate (40 per cent arsenic as A20a),and also unpoisoned plots were used as controls. As a result of three years' experimental work, during which comparative toxicity tests of more than 1000 poisons and poisonous mixtures were run, two materials stand out as commercially possible boll weevil poisons in comparison with the standard commercial calcium arsenate. One of these is a special calcium arsenate containing about 20 per cent arsenic. as against the 40 per cent arsenic content of ordinar). commercial calcium arsenate. As the cost of arsenates is roughly proportional to the arsenic content, a large saving can he achieved by using a material of lower arsenic content, if it can be made effective. After a study of various methods of production, this special calcium arsenate (20 per cent arsenic] was cheaply and easily prepared by heating calcium carbonate (precipitated chalk) a.nd white arsenic in the presence of excess air at, a temperature of 650" C. The other material, a sodium fluosilicate, can be obtained as a by-product in the manufacture of acid phosphate. I n all the preliminary tests, both of these materials show a weevil toxicity at least equal to the more costly commercial calcium arsenate, on a pound-per-pound basis, and do not cause any economic damage to the cotton plant. They arc both relatively easy to make and tile raw materials necessary for their msnufacture are available in sufficiently large quantities to supply any demand for them as insecticides. They could be placed upon the market at least as cheaply as commercizl calcium arsena.te. The Chemical Warfare Service has t.aken these poisons from the laboratory stage and developed them to a point of real economic import.ance in the field. Sodium fluosilicate is not a
Vol. 20, No. 10
Ship-Bottom Paints
The accumulation of marine organisms on the hulls of ships presents a problem t,o ship owners and operators, the importance of which can hsrdly be exaggerated. The growths consist of many forms of marine life, the principal ones being the barnacles, which are shell fish, conical in shape, attached at, the base of the cone, and reaching sometimes a n inch in diameter; and hydroids, which are grasslike organisms. Other animals which attach themselves to ship bottoms arc the Tubularia., which forms hard tubes along the surface, tlie Ascidians, whicli form in large clusters, and the Rryozoa, which formin round, flatpatches. These growths may accumulate to such an extent that they project several inches froni tlie Imll, but even in small amounts they cause a roughening of the surface wliicti increases the difficulty of propelling the ship through t,lic. water. The immediat,e effect of this fouling of t,he ship bottom is:an in-
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Fisure 2-Testing New Polsons on the Boll Weevil. Insert: Boll Weevil (Maanifled)
crease in the fuel consumption of the vessel, amounting at times to 25 per cent and a lowering of the speed of which tlie vessel is capable. Also the vessel must periodically be drsdocked to clean the bottom, t.hus cutting down its effective time afloat. The extent of growth depends largely on the season and latitude. It is practically continuous in t.he t r o p ics, and diminishes in the temperate zones, where fouling occurs only in the summer, the season becoming shorter as the latitude increases. Since they live only in sea water, it is
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INDUSTRIAL AND ENGIi VEERING CHEMISTRY
possible to kill off all growths by docking a vessel in fresh wat.er. The drawback to the remedy is that the shells still stick, furnishing resting places for new growths. The organisms abound principally near the shore, very few being found in the open sea, so that fouling starts largely while vessels are in harbor and at rest. These effects are important to commercial ships of all kinds from a purely economic standpoint, and apply with equal or greater force to naval vessels. I n the latter ease the very life of the shipitself, the difference between victory and defeat, inay depend on the speed which can be attained. The effect of increased fuel consumption is to decrease the effective cruising radius of a vessel. Decreased speed is serious in affecting
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the thinner or volatile solvent. A large variety of materials has been used, the principal object being to find the proper relation between the vehicle and tlie toxic. If the poison is too soluble, or is too loosely held by the paint film, it will soon leach out, leaving the paint unprotected. On the other hand, if the poison is too insoluble, or if the paint film is so impervious to water that the toxic cannot act, growths will readily occur on the surface. Although a large number of poisons have been tested, so far nothing has been found so effective as the oxides of copper and mercury. As a vehicle, rosin modified by coal tar, other gums, and a variety of synthetic resins, seems to liold the most promise. Fumigation
Fi*ure 3-Ship-Bottom Plate Showin Effect of Toxic Paint in Pzevenfing Marine erulxths k i t : ordinary paint; right: toxic paint
the time required t.o reach any given strategic position, as well as during an actual engagement. The Navy is at present using a paint made of domestic materials and of fairly low cost, but this paint is not entirely satisfactory-consequently, the Bureau of Const,ruction and Repair of the Navy Department has for several years been carrying on an intensive program of research looking to t.he improvement of paint.s now used by the Navy. I n its simplest terms, the problem inay he stated as follows: (1) To develop a paint that will remain permanently on ship
Every ship arriving at United States Quarantine from a foreign country is required to show a certificate of fumigation of recent date. If this certificate is not produced, the ship is turned over to the United States Public Health authorities for fumigation. The fumigation is conducted chiefly to insure against the introduction of bubonic plague and typhus fever into the country. I3ubonic plague is transmitted to man from rats by means of the Rea which carries the bacillus of the plague. The rats and their parasitic fleas are killed by fumigation. Typhus fever is an acute iiifect,ious disease transmitted from an infected person by the bite of the body louse (Pediculus vesestimcnli). Every person arriving a t Quarantine infected with lice is detained until deloused, and tlie baggage of such passengers fumigated.
bottoms. (2) To include in such a paint a material that is sufficiently toxic to kill or mevent the attachment of the marine organisms,
obtaining ' food from the surrounding ware;. It is therefore necessary for the poison t o a d only during the period of attachment. (3) To develop an auxiliary paint (applied under the antifouling paint) to protect the steel plating from the corrosive action of the sea water, and to prevent electrolytic action betweeii the plating and metallic constituents present in the toxics. (4) To develop these paints from domestic material, and to keep the cost-of manufacture and application as low as is consistent with proper functioning.
Figure I-Mofh?d of Fumigating an Army Bakery with Latest Type Gas Which Warns againsf Dangeroms Concentrations Personnel protected by masks
The Chemical Warfare Service has been cooperating with the Navy Department in a study of this problem, working on two different types of paint. The first is the so-called hotplastic paint, which is applied in a melted condition, and solidifies on cooling. The other is the varnish type, which is a p plied cold, and dries by evaporation of a solvent. The hot-plastic paints form a muell heavier coat than the varnish, and for this reason the cost of painting is much higher. However, under certain circumstances, such as an unusually long cruise, the longer life of the plastic paints would render their use advisable. The Chemical Warfare Service has developed a paint of this type which, on exposure to marine growths in sea water on a small scale, has given very excellent results, and is now being tried on the bottoms of several destroyers. By far the larger number of shipbottom paints are of the varnish, or solvent, type. These paints consist essentially of a vehicle, which is a gum, resin, or similar material; the pigment which gives body and color to the paint; the toxic; and
Hydrocyanic acid, which is a very penetrating extremely toxic gas, has been very widely used. However, on account of its extremely poisonous character, and ,its lack of suitable warning properties, under certain conditions, it is a constant source of danger to human beings and domestic animals A great many fatalities have occurred by persons coming into contact with the gas either during the process of fumigation or immediately thereafter, before the gas is entirely removed from the fumigated areas. Previous experience bas shown that in refrigerated chambers there may be a condensation or absorption of hydrocyanic acid, which will not be removed by ventilation. Such chambers, apparently free at the given temperature, will, on warming, volatilize sufficient hydrocyanic acid to form a lethal concentration, Casualties have also occurred by leakage of the gas through cracks into adjoining rooms and to the outside in close proximity to the place of fumigation. All these accidents are undoubtedly due to
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the weak odor of the hydrocyanic acid gas, which is insufficient to warn the average individual before he is overcome. The Chemical Warfare Service, in cooperation with the Public Health Service, developed a method of fumigation whereby cyanogen chloride, an intense war tear gas, is generated along with the hydrocyanic acid. This compound is also highly poisonous, so that the mixture is almost as efficient as the hydrocyanic acid alone and, in addition, gives instant warniiig of its presence, even in sublethal concentrations. The fumigating mixture is generated by adding a mixture of sodium cyanide and sodium chlorate to dilute hydrochloric acid. This method has been adopted by the Public Health Service and is now in general use by it. Public Health Service Mask
Since workmen engaged in fumigation need respiratory protection, the Chemical Welfare Service has investigated the possibi1it.y of furnishing a special mask which would have a
FIBure I-Nos-Ergloslve
Tear-Gas Nand Grenades (One-Third Actual Size) fur Control of Mobs k i t : m m b l e d ; dght: firing mechanism removed
long service life against this mixture. Hydrocyanic acid and cyaaogen chloride being the only toxic gases in which the mask is to be used, the mask could be made to have a high capacity for absorbing them. An investigation was made of absorbents for these two gases, as a result of which a combination of two abmhents was found which was particularly effective. These two absorbents are filled into a modified war canister called the Public Health Service canister, of the Eame shape and size as the war canister. The mixture is proportioned so that when the cankter is exhausted, cyanogen chloride, rather than hycrocyanic acid, penetrates. The cya.nogen chloride, being very easily detected by its odor, serves as a warning agent of the exhaustion. But the amount. of cyanogen chloride which penetrates a t exhaustion is extremely small for some time, so that the wearer of the mask a t exhaustion may, in a,n emergency, finish his work in the gas with little discomfort. although he should ordinarily leave the contaminated atmosphere as soon as lie detects evidence of cyanogen chloride. When the canister is exliaustcd, it is easily replaced by a new one. The Public Health Service canist.er has a moderate brcatliing resistance, and will protect for several hours against such concentrations of cyanogen chloride and hydrocyanic acid as are normally encountered. I t may be attached to either of two types of war masks and carried in the regulation army gas mask carrier. Ammonia Mask I n the operation of ice plants, in the handling of ammonia cylinders, and in miscellaneons chemical plant work, .leaks of
VOl. 20, No. 10
ammonia occur which allow highly irritating and dangerous concentrations of this gas to accumulate in the air. Further, it is often important that the leak in an ammonia pipe line in an ice plant be quicldy repaired in order to keep the plant in operation. In this case ammonia is the only irritant or toxic present. Ammonia fumes may also be encountered in firefighting; in that case carbon monoxide may also be present. The war-mask canister does not give satisfactory protection against ammonia, hence a special mask is needed. Before the war ammonia masks had been used t o a very limited extent. Tlie canister on the masks contained pumiceor some such inert granular substance which had been soaked in sulfuric acid. The performance of the canisters was unsatisfactory, for several reasons: The canister had a very high breathing resistance; the sulfuric acid corroded the canister parts: and the inhaled air was often very warm and quite irritating from fumes given off by the absorbent. The Chemical Warfare Service developed a new absorbent for ammonia which avoided, to a large extent, all these objections and which absorbed more than twice as much ammonin as the old absorbent. The ammonia canister is the same shape and size as the war cankter, has a low breathing resistance, and will protect against low concentrations of ammonia for several hours. In high concentrations-for example, those which cause an unbearable skin irritation-the canister will protect for a longer time than the skin irritation can be tolerated. Furthermore, when thecanister isexhausted, theamount of ammonia which is smelled is usunlly small for some time, so that it is not necessary for the wearer of the mask to leave the place immediately after the ammonia starts to penetrate the mask. When the canister is exhausted, it is easily replaced by a new one. The ammonia canister may be attached to either type of army gas-mask face piece and may be carried in the side carrier under the left arm or on the back, as desired. Use of Tear Gases in Controlling Mobs TIE use of bnllets to control unruly individuals or mobs when this control can be attaincd by the use of tear gas is a crime which should no longer be tolerated in a civilized nation. In the coal strike in Colorado in November in 192i, “state police and mine guards poured bwnfire into a crowd of 500 striking coal miners and I. W. W. a@tat,ors approaching the Columbine Mine, about thirty miles north of Denver,” according to the Literan~Digest of December 3, 1927. Moral suasion was used against t,his crowd without effect, then bullets were used, five or six persons were killed, and more than twenty men and women were wounded. A few tear-gas grenades would have stopped this crowd just as effectively as did the gun fire and without permanently injuring anyone. During the labor disturbances of 1922, a mob of miners wcre quickly a,nd easily brought under control at Coatesvilie, Pa., by a state police officer using three tear-gas grenades. This officerendeavored to stop a mob organized for the purpose of destroying themineworks. Hisorders to disperse beiugdisregarded, and being threatened by one miner, he quickly threw three tear-gas hand grenades just in front of the mob. The effect was instantaneousand the mob stampeded, most of them before actually feeling the effects of the tear gas. No further trouble was experienced in this vicinity during the strike. Tbe Cliemical Warfare Service as far back as 1920 suggested the use of a simple tear gas (chloroacetophenone) in small ha,nd-thronn bombs or grenades, as a far more effective and humane method of controlling mobs and unruly individuals. Since that time the Chemieal Warfare Service has developed several tJ’pes ofharmless nonexplosive tear-gas grenades that have proved so effective that the police departments in nearly all the large cities have adopted them,and they arenow being manufactured by commercial firms.
October, 1928
INDUSTRIAL AND ENGINEERING CHEMISTRY
lo&?
These devices may be used by persons of average intelli- character both in war and in peace, this gas has been very gence with less training than is necessary to use firearms p r o p intensively studied by the Cherhical Warfare Service, parerly, and any misuse of tear gas could hardly have the disas- ticularlywith aview to providingsome practical methodof protrous effect possible from firearms. I n concentrations ob- tection against it. Up to within a few years ago the only detainable in the open, chloroacetophenone has no poisonous vices that could be used were the oxygen helmet and (he hose effect, but acts only upon the eyes. It causes a sharp, sting- mask. These devices were so bulky and handicapped the ing sensation in the eyes, followed by a copious flovv of tears. wearer so much that. they were not practicable in many cases. Higher concentrations cause the eyes to remain completely The development of a mask with a self-contained canister for closed. These effects usually last for not more than a few protection against carbon monoxide was first undertaken minutes after leaving the cloud. There is no record of a pcr- by the Chemical Warfare Servicc a few years ago at the reson being permanently injured from the effectsof chloroaceto- quest of the Xavy Department for protect,ion of sailors in subphenone. Alt.hough the physiological effects of tear gas are marines in case of accident to machinery when submerged. The removal of carbon monoxide from air was a difficult pot,ent, the psychological effect may be even problem, becauso its high volatility makes it difficult to abmore potent. hlen fear sorb, and because it has a very low solubility in solvents, and t h e u n k n o w n . It is is clicmically inert. The problem was further complicated easier for man to main- by tlie fact tliat a satisfactory “absorbent” must remove practain morale in the face tically a11 the carbon monoxide in tlie inhaled air in about 0.1 of bullets than in the second, the time for which the inhaled sir is in contact with p r e s e n c e of invisible tbc absorbent. It must do in this freezing weather as well as a t gas. There is always normal temperatures, and it must have tlio other properties of an uncertainty in their a gas-mask absorbent sucli as hardness, moderate breathing minds as to the effects resistance, etc. of the gas. The only As a result of extensive research the Chemical Warfare Serreal danger of s e r i o u s vice has devised a mask which affords complete protcction injury from using tear against carbon monoxide for a limited time, and by changing gas is from the possi- canisters indefinite prot,ection can be afforded. This mask bility that members of has been adopted by the Navy for submarine crews and the t h e c r o w d m a y b e application of the principle has found widespread use in intrampled upon in at- dustry. I n addition two valuable by-products resulted from tempts to escape. this development, First, an improved and cheaper method There are many di5- of making iodine pentoxide; and second, a simple detector for cult situations in which carbon monoxide vhieh causes a color change from the original the use of tear gas re- white of the detecting material t o bluish F l g u r e 6 4 1 d TylreMaik(w1thOxygen q u i r e s j u s t a’ Tanks) for Protection against Carbon knowledge and tact as g r e e n , t h o n violetMonoiida brown, and finally are required to X o t e complicrted apparsrtus ieguiied mobs bv other means. black, depending upon t h e cnncentrat,ion of and it must not be inferred that tear gas can or should al: ways take the place of other means, but there are many io- carbon monoxide. The stances on record in which tear gas could have been used with indicator will determine quickly and with suffiil conseqnent saving of human life. cient accuracy whether Protection against Industrial Poisoning or not a dangerous concentration of c a r b o n As most of the industrial poisons common in hazardous monoxide is p r e s e n t . industries havc been proposed as effective chemical warfare The detector is proving agents, t.he Chemical Warfare Service has studied very exten- a valuable aid in mine sively the problem of protection against these poisons. Such rescue and r e c o v e r y protect.ive measures are, of course, directly applicable to in- o p e r a t i o n s after fires dus1:ry and have proved a boon to those engaged in many and explosions, and for hazardous occupations. testing air around blast Carbon monoxide is one of the most dangerous industrial furnaces, gas producers, poisons because of its lack of odor, color, and taste and its water-cas and coal-eas rridespread prevalency. Although its physical properties are p l a n t s , aIld at otoher Figure ?-New (Submarine) T e of carbon Gas Mask for Proteclion seainst &bo” not such as to make it a pract.ica1 cliemical warfare agent, yet ,,laces Monolids it was often encountered during the World War and protec- monoxide is a hazard. Note SirnDlititY of equbment tion against it was a serious problem. The explosion of high It may be also used to esplosives in enclosed places, such as dugouts, interior of a promote furnace economy by indicat,ing the presence of carship, etc., causes the generation of deadly concenirations of bon monoxide in flue gases. carbon monoxide. Machine-gun fire in tanks and pill boxes Carbon dioxide, the twin brother to carbon monoxide, but and the use of explosives in sapping operations are also respon- not so dangerous, is a product of ordinary combustion and of sible for carbon monoxide casualties in war. Industrially, the respiration of men and animals. The question of elimicarbon monoxide is encountered very generally. It is a con- na.ting the injurious effects of carbon dioxide in places where stituent of the usual illuminating gas supplied to cities for adequate ventilation cannot be secured is an important indusheat and liglit, and is the cause of many deaths each year. It trial problem. It is of direct military importance at the presis also present in the exhaust gases of gasoline engines, in boiler ent time owing to the necessity of providing some means of rooms with defective ventilation, in fires, and in general combating poisonous effects of carbon monoxide in submarines wherever Combustion is incomplete. Because of its deadly when the crews are entrapped therein, through accident or
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other emergency, as in the recent collision of the 5-4. The Chemical Warfare Service is now endeavoring to find some means of solving this problem. It appears that, although difficult, a solution will ultimately be found, and when found will prove of very great value commercially. Conclusion
Other examples might be cited to show the widespread industrial usefulness of the many peacetime researches of the Chemical Warfare Service, but the foregoing are believed sufficient to illustrate the point. It should be pointed out that the majority of the most valuable contributions of the Chemical Warfare Service to industry have been entirely incident to its regular military researches. Others have been undertaken a t the request of various other government bureaus because of special talent and equipment which thisservice has for investigations in the field of poisonous materials and protection therefrom. In all cases. once a solution of the problem is reached and a new device is designed or produced to solve a given difficulty, the Chemical Warfare Service does not
Vol. 20, No. 10
attempt quantity production or supply commercial needs for this device. It merely makes a sufficient number for governmental use and publishes its findings and results so that commercial firms may engage in the manufacture thereof. The Chemical Warfare Service was provisionally established during the summer of 1918 and inherited the chemical warfare research and development work theretofore carried on by other agencies of the Government, notably the Bureau of Mines. Hence the initial steps of many of the foregoing achievements were taken by these other agencies and later developed by the Chemical Warfare Service. Since its permanent establishment in 1920 the appropriations for the support of the Chemical Warfare Service have averaged only 0.37 of 1 per cent of the appropriation for the Army. Of this sum approximately one-third has been devoted to research and development. It is believed that the contributions of the Chemical Warfare Service to industry alone have more than amply justified the sums devoted to research, to say nothing of the tremendous progress made in the protection of our Army and Nation against enemy chemical warfare in any future emergency.
Reenforcement of Rubber by Fillers‘ John T. Blake SIMPLEX WIREAND CABLECo., BOSTON,MASS.
A new theory of pigment reenforcement is presented, ULCANIZED rubber He next proposed the conin which a reenforcing filler is defined as one which as ordinarily used in cavity factor as another index forms a bond with the rubber matrix that is stronger of improvement. This is dec o m m e r cia1 articles than the matrix itself. A molecular tensile curve fined as the ratio of one-half has fillers or pigments comsubstantiates the conception. The mechanism of t h e t e n s i l e product to the pounded in it. The fillers fall filler dispersion is considered, and the work of Langproof resilience. This value into two general classesmuir and Harkins is applied to rubber. Calculations becomes unity when the tenthose which i m p r o v e t h e of the quantity of dispersing agents and of the heats sile curve is a straight line. quality of the product and of wetting conform to experimental values. The means T h e s e two methods give those which dilute the rubber of extending the reenforcement of rubber by carbon values for the effect of a filler and only lower the cost per black is discussed. a t a single concentration. To unit volume. The members express the effect of the filler of the first class are called reenforcing fillers and are chiefly carbon black, zinc oxide, over the useful range of loading, the “A’Jfunction is used.3 magnesium carbonate, and certain clays. The members of This “A” function is the relation between proof resilience the other class are called diluents and can be almost any and volume loading. material desired. Whiting, lithopone, and barytes are exIf the “A” function is plotted for a reenforcing filler, it rises amples of this type of filler from the value of the base mix to a maximum and then deA good accelerated pure-gum stock will give a tensile creases. The volume loading a t which it crosses the ordinate strength of 3000 pounds per square inch. When 30 volume of the base mix is the concentration of the filler at which per cent of carbon black is added, the compound develops a reenforcement ceases. The “ A A” function is the integrated tensile strength of 4000 or more pounds per square inch. Co- excess of the “A” function over that of the base mix, and is a incident with the increase in tensile strength, there is a de- measure of the reenforcing value of a filler. crease in stretch and an increase in resistance to abrasion, Wiegand, however, has chiefly been concerned with the stiffness, and resilient energy. evaluation and use of the reenforcing effect in a practical way rather than with the mechanism of it. A consideration of the Theory of Reenforcement-Previous Work mechanism is essential if we are to extend the range of its Wiegand has studied the reenforcement of rubber by carbon effect. Reenforcement may be expressed as an increase in black and has proposed several methods of evaluating the tensile strength. Spear has offered a theory of carbon-black effect. He concluded from a theoretical viewpoint that the reenforcement that is the only real attempt to date to explain proof resilience-that is, the amount of mechanical work this phenomenon. He postulates that when rubber is necessary to stress 1 cubic inch of rubber to rupture-is the stretched the resulting lateral contraction develops very thin best index of improvement.2 This increase in proof resilience films of rubber matrix surrounding the harder rubber aggreis conveniently measured by determining the area beneath the gates. These films ultimately become quite thin and are stress-strain curve and converting to suitable units. The more solid and rigid. When gas black is dispersed in rubber, improvement in quality is usually measured by an increase in its fine state of division develops these thin rigid films markresistance to abrasion. edly, with the result that the rubber is stiffened and strength1 Presented before the Boston Group, Rubber Division, American ened.
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Chemical Society, May 9, 1928. * Can. Chem. J . , 4, 160 (1920).
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Wiegand, IND.ENG.CHsar., 17, 939 (1925).
