CORNELL UNIVERSITY LIBRARY Cornell University Ubrary UG447.U58 C4 Chemical development SertlOT^U^^^^^^^ olln 3 1924 030 765 899 Overs The original of this book is in the Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924030765899 WAR DEPARTMENT GiffiMiCAli WARFARE SBRVIdE RESEARCH irviSION AMERICAiJ UNIVERSITY EXPERIMENT STATION WASHINGTON, D. G. MAJOR OEHERAL W. L. SIBERT, DIREOTOR COLONEL G. A. BURSELL, CHIEF OF RESEARCH DIVISION CHEMICAL DEVELOPMENT SECTION W. K.^' LEWIS, IN CHARGE SUl^ARY OP ACHIE-VEiJENTS 1917 - 1?18. / The ChemiGsI Development Section of the Eesearoh Division is an outgrowth of the JJanufaotm-ingf Development Division formed undejf the leadership of Dr* W^ K» Lewis, a pioneer m^nher of the early Bureau of Mines organization for Wai: Gas Investigations. The original Manufacturing Development Division worltad on cshemical and meohanical rer seaarah and development prohleiBs. Later it contained an organization known as the Emergency Squad. This squad was formed with Mr., R» Qt. Kuowland as its leader at time when it was n;ecesssrj- to have a group of men who could quickly turn their attention to any problems of especial importance with a view to obtaining a speedy and accurate solution. Consequently^ their work was done largely in conjuno-tion with that of other divisions. In many of the problems originating at the Amer- ican Uiiiveisitjr Experiment Station, it was necessary to In- vestigate and often secure large quantities of chemicals not in general use, or to locate some special piece of apparatus. This work, together vith rush chemical testing, was done by the emergency unit, A large number of special analyses and tests were made when men were not available in other laboratories, and, in fact, the work of these men varied from messenger serviae to the study of little known and extremely poisonous gases. In connection with many development possibilities, this unit did work of great value in securing the prices, location, and availability of necessary supplies. In peace times, such investigations would have been comparatively simple, but under war restrictions and existing war in- dustries' regulations, the work was at times very difficult* Shortly after the formation of the Emergency Squad, the mechanical research and development work, which had been entirely in the hancfe of Mr. H. H. Olark, was so divided that Mr. Glark continued with a certain portion of the work, while the liaison service bet^'een the Bureau of Mines and the Gas Defense Service was furnished by a unit under the direction of I.Ir. B. B. Pogler. At a later date, all the mechanical research and development work was placed in charge of Mr. fl. B. Fogler, directing the Mechan- ical Research and Development Division. Some time later the work of the Emergency Squad and also the chemical research and development work of the Manufacturing Development Division were brought together in the Chemical Development Section of the Research Division of the Chemical Warfare Service. This seotlon was under the leadership of Capt. R. G. Znowland, and afterward, under lieut. Allen Abrams* The organization continued work on amergency problems, and assisted other sections in the development of cjhemical processes whioh were to be put on a manufaoturing basis. The following report gives a brief account of the problems with which this section has been concerned. The discussion is presented by subjects rather than chrono- logical order. GHABQOAL BEW SOURCES Qg QHAHaOAL: In Nox'ember, 1917, the National Carbon Company had developed the first gemi- commercial charcoal steam activating unit, and required the services of more men than they could supply. Consequently, this section supplied two men, one of whom remained permanently at that station. These men continued the rork on this furnace until definite recommendations were made to Mr. Dorsey, who was developing the large commercial unit. This small unit consisted of a 7" clay saggar, approximately 2' long, provided with a hopper feed and slide discharge. This sagger was surrounded by a resistor carbon electric furnace, enclosed in a large jlay cylinder. The entire furnace was packed in silocel and surrounded by a brick wall. The steam was admitted through a ?./4" iron pipe running up from the bottom and terminating in -2- the middle of the furna<3e." This fxtrnaae was continuous in aotion, providing for the admission 6f rai"' coal at the top, its passage down into the hot zone at about 900*^0, treatment with ste^ and the resulting activation, and finally cooling in the lower part of the fufnacse and dis- cbargifig as at finished product at the bottom. OPERATIOli AMB OO^rnQL Of THE DOR SITE aHABQOAL HEATERS AT ASTORIA; L«I. At the time of the investigation covering the month of April, 1918; there were ten steam ireaters in operation at the plant of the Astoria Light, Heat & Power Company. The main difficulties encountered in the operation of these furnaces were as follows: iTregulatity in quality of the treated charcoal; rapid burning out of the nichrome heater tubes, necessitating long aiid frequent shut-downs of the furnaces; and ineffective temperature control in the heater tube» Complete investigations were made of the operation and control of the two methods of heating then in use, - the swirling flame and the surface combustion. For this purpose two furnaces, one of each type, were used as ex- perimental furnaces, and an exhaustive study made of their relative merits* A study of the data obtained in these tests resulted in the adoption of a new method of tempera- ture control'. The following Conclusions relative to the -4- operation of the furnaoe were also indicated: Irregularity of quality can be due to temperature fluctuation at the reactive zone of the furnace; rapid passage through the reactive zone, due to steam pocketing or breaking up of a oake; and steam condensation on the treated charcoal after treatment. Temperature charts which were plotted from data, obtained from thermo couples inserted in the walls of the furnaoe, indicated that the best method of temperature con- trol was by means of a couple inserted at the reactive zone and against the nichrome tube. The best location for the control couple in the furnace was located by a series of tests on the temperature gradient along the tube. Data from these tests furnished a basis for the comparison of the two types of furnaces, and indicated that surface com- bustion design gave the best temperature control. STRUOTURE OF OHARQOAL : In spite of the fact that so much work has been devoted to the development of high absorption charcoal for gases, there is practically nothing known con- cerning the manner in which the structure changes with in- crease in absorption value. If this were known, it might suggest the way in which this structure could be duplicated in manufacture. This was particularly important since the problem of reproducing the German charcoal had been turned over to the Research Division, -5- The only method available seemed to be the study of the amount of readily oondensible gas absorbed at different equilibrium pressures of the gas^ Prom the shape of the ourve obtained on plotting this data, it would be possible to calculate the size of the pores by a formula based on thermodynamic considerations. The necessary apparatus for this investigation was assembled and measurements were made . The apparatus was complicated and required careful operg.tion to obtain the required precision. A great aiaount of care was expended in obtaining charcoal absolutely free from foreign gases, since it was believed that this point had never received the proper attention » and that previous work had involved the absorption of th« gas in quest ion » not on a pure carbon surface, but on a surface upon which air, water, etc., had already been absorbed. It was planned to make a study of a series of our own charcoals between and 60 min. facoel. chloropicrin test) in order to ascertain the nature of any systematic variations, and also to study other representative char- coals, such as the German^ English, and French materials* This problCTi was under consideration when the war ended. The persons en gaged in this investigation were: 0. K, Relman^ J. B.- Dicksen„ and H. M. Cyr. -5- PROPPOTIOl? OF BAa?OHITE : The use of poisonous gases in the war made the perfection of suitable proteotive devices im- peyative, and this !was particularly ti?\ie: in the cjase of c^arooal. Oocoanut shell oalcirted.,. g±6und,. and. treated at a temperature of from 850 C}«950°G «?l:th superheated steam prodoAcsed a sa'tisfa<^tory absorbent^ but the limited amount of shell availalile made a secondary source of charcoal ad- visable. The laboratory of the National Garbon Oompany determined the experimental conditions for the activation of anthracite. A unit of the Chemical Development Seotion, under the direction' of Hr S". Wilkins^ was organized to develop the method. The fir&t trials using a Glover-West vertical fr oontimious-feed retort » v?as not successful, but the second trial, using intermittent, inclined retorts, gave (julte satisfactory results. The following schedule produced the best material: Time of treatment 48 hours. Charge BOOO lbs. Size green coal charged 8-14 standard mesh Temperature 900° to 950°(i Steam 100 lbs. per hour This charcoal averaged 15 minutes on th6 acceler- ated chloroplcrin test. The loss of weight in treatment varied from 25^ to 23^, depending upon the degree of acti- vation obtained. Steam was run through hot coal only, since the water gas reaction (0 -f- HgO s H2 -^ 00) does not take -7- plaoe, appreciably, below a temperature of 850°CJ. This reaation plays the chief part in the activation, and has a distinct cooling effect^ so that if steam were run con- tinuously, the proper temperature would not be maintained. The retort temperature was determined by the appearance of the flame formed at the upper door by the combustion of reaction products. The limited capacity of the producers prevented excessively high temperatures » and, although as earful control as possible was maintained » the product was rarely uniform. The average, passing a IS min. standard, was about 75^. As the demand for charcoal became greater, the supply of coQoanut proved to be insufficient, and the Batchite Plant at the Springfield Gas Light Company went from a development to a production basis. Beginning about July 1, 1918, nearly 5 tons a day were produced. This output was increased rapidly until a 10 ton minimum was passed, with a maximum production of over 15 tons in a single day. Shortly after production was begtn, the Gas De- fense Division assumed control of the plant, and the work was continued by them until the end of the war. AIR DENSITY OP BAT3HITE : One of the most desirable materi- als for the gas mask absorbent was a charjoal laade from nut shells and fruit pits. The supoly of these materials -8- being limited j it was found neaessary to look for substitutes. Anthracite coal, when subjected to a certain heat treatment, had been found to yield a product wi,th an average absorption capacity somewhat les,? than that made from nut shells. This material Xb technically known aa Batchite. A close examination of s^ sample of average batchite shows that the individual particles have densities within the limits of 1.20 to 1*60* IDhe less dense particles have a greater absorbing power for toxic gases than the heavier ones, and it was therefore proposed to apply air separation to the mixture. AH the factors governing this separation were thoroughly studied. For this purpose, a machine was developed in which the batchite was introduced into the lower portion of a vertical tube, through which tube a blast of air was blowing. The air velocity was so regulated that the lighter particles were blown out at the top of the tube into one compartment while the heavier particles dropped out at the bottom Into another* By this means, average batchite was separated in- to two portions^ the lighter of which had an absorbing power much greater than the original material* STEAM .DISTILLATION OF ORUIJE OOJOAKUT : In December, 1917, Oapt. Woodruff and Hr. Dorsey desired to try the steam dis- tillation of ground cocoanut in the horizontal retorts at Astoria^ This section sent a man there to carry out this -9- work with the assistance of the Gas Defense Service. It was first necessary to equip the retorts with some means of steam distribution, as they were the ordinary D- shaped horizontal gas retorts* This was done by making a false bottom of channel irons, perforated with 1/8" holes, under which perforated steam pipes were run. The steam used was measured by an orifice. As the retorts were maintained at approximately 900^0. the steam at that temperature had a very destructive oxidizing action 04 the iron channels and pipes* After 84 hours running, a half inch wrought iron pipe showed in- crustations of iron oxide I/8" thiclc, both inside and out- side, plugging up most of the holes. The same was true of the channel irons which also bent and buckled in the middle under the weight of the charge. It was deteirained that this method of introduc^ing steam was impractical, as the life of the iron work was so shorty and it was impossible to maintain open holes for even distribution of the steam. This rapid oxidation of the iron was Slightly less acute on the surface of the channel iron exposed to the carbon, but the under side of the channels and the steam pipes were in perfect condition for oxidation, - temperature of 900°C and an atmosphere of superheated steam. In spite of the short life of the steam distri- buting system, it was" clearly shown that the carbonizing -10- time cijuia be cut down frcfti IS hours to 8 hottrs with better results;- Furthetniot^,, the material so distilled had an aotlvity of fr/om to- 4- minutes faccelerated ohlbropior-in test ) , while without' the^^ steam treatment , the material had no or even a "negative" activity (i.e. was not completely carbonized). This process produeed better- material for the main activation process in the Air or Dorsite Treaterfe. About 500" lbs; was determined to be the best charge per retort.- Work was then stiarted to design improved methods of introducing the steam, which work was continued by the Gas Defense Division. The results of this work werei This introduction of over one hundred retorts equipped with a perforated fire- clayk falsebottbm; an increased production in these retorts due to the decrease in time of carbonization,- and further- more».this advance in design made possible the utilization of these retorts for the ptoduction of'batchite when later introduced* DORSE Y STEAK TBEATERS : Twice » when difficulty had been ex- perienced in operating "the Dorsey Steam Treaters at Astoria, a man was furnished from this section to assist in deter- mining the cause for and remedying such difficulty* The most serious trouble was the irregular quality of the product* This was traced to large fluctuations in temperature v- which were the result of two causes. First. -11- the formation of "gas popkets", causing the pyrometer in that tube to show a marked Increase in temperature, due to the fact that it was in a.' pocket of gas and no longer imbedded in the charcoal where an enthotheTmic reaction was taking place. Secondly, because of this increase in temperature, the burner men out down the gas fired to that retort, and consequently when the effect of the decreased heat supplied was felt, the gas pocket had broken and the material had dropped to a low temperature. The gas supply was again increased # and the tanperature raised. This method of operation gave a vexT irregular temperature con- trol, and as the rate of passage of th-e material through the furnace was constant » the quality vatied with the different treatment given to it. By insisting that tha gas supply be changed only as a last resort to prevent burning out of the tube, and breaking the pockets as soon as formed, it was possible to get a quite uniform temper- ature and an iraproVed product ^ Work was also done collecting miscellaneous data on the furnaces, such as temperature gradients, horizontally and vertically ihside'ahd outside of the nichrome tube, and determining the quality of the product under various con- ditions of' temperature and rate of flow. Tubes were coated to varying heights with alundum cements, and provided with baffle walls of different heights. The work of the men from this section was not confined to one particular Job, but *12- they studied related problems, such as gas analyses of the various products of oomhustion, eto. All of this work was of great value in the further developments of this type of furnace. -IHTRQDUGTION OF BATCH I TE AT ASTORIA: When the production of batchlte at Springfield, Mass., proved to be a success, it was decided to introduce its manufacture at Astoria, using horizontal retorts. Previous work had shown that a vertical type of .furnace was unsatisfactory for treating and activating- batchlte^ due to the "gas treating" of the material by the products of combustion. At Springfield, after, finding the vertical retorts to be a failure, the in- clined retorts were tried» using a thin layer of the coal over a perforated steam -pipe. This was successful, so there was no reason why the horizontal steam-bottomed re- torts, at Astoria should not be even more satisfactory, since they would give a large area with a very shallow layer of material. A few unsuccessful runs were made by the Astoria organization but with no results, -the material testing under 5- minutes (ac(^erated ehloropierin')'. Lieut. Holton of this section, who had had experience, was then sent out to put the thing on a production basis. Firsts a series of runs were made on four retorts in order to determine the best operating conditions for this type of furnace. Tt was found -13- that: fl) About 1000 lbs. of raw aoal was thQ best charge to use; C2) the tempeyatura must be maintained above doO^Q for good results; {3) the time should be at least 36 hours, and for the best results^ 48 hours; (4) the maintenance of a sufficient and uniform distribution of steam was essential; (d) due to the leaks in the ends o'f the false bottoms, much more stoam had to be us«d in the retort than was needed to activate the ooal (about 250 lbs- of steam per hour were used per lOOC lb. charge); (6)- it was necessary to keep the material well stirred. With thes^ points in mind, new re- torts ware started as soon as. equipped with suitable steam orifices for measuring the stean flow. It soon became evi- dent" that the majority of the retorts were in such poor condition that only a saall proportion - 20^ or so - of the steam actually reached the ot>al. With good retorts, the material would averag^e 15 to 20 minutes f accelerated chloro- picrin test) with some puns as high as 27 minutes, while with poor ret ort^.th^ test would run, aaywhejre from one minute to 10 or 12 minutes. Before long, 40 or 50 retorts were in operation turning out about. 10 tons of material a day, of- which only 30^ to 50% «ra.s passa]ble. After a change Of organization in which special men were put in charge of keeping the retorts patched up and in good condition, the amount of passkbaV mater lal was raised to 70^. ' The different stage-s, of the process were as follows: The raw coal, receijdjd at the dock, was. ground at a special ■, , ; . :.. ■' •■ -14- . :. grinding, plant antj soreened 6^14 mesh, bagged or driManed, and sent to the retort house. Thex^ it was loaded by hand, either di^eQtiy with the retorts or else by the charging scoops. When charged ^ It was levelled off to give a four inch layer, and stirred every hour for 48 hours. The steam was kept on at all times, unless the temperature fell below 800 °0,. when it was shut -off until the temperature again reached 850*^0. Hh^. discharge was run directly into a steel drum or caz^;- and allowed to coolfc and later drummed and sampled. The. product was then finished and ready for shipment. Qn large scale product ion^ it was impossible to get an average passable material of over 15 min. (accelerated chloropicrin test). The entire batohite program was to build up a reserve supply in case of emergency.. As a reserve, batohite, and its process, stands as a valuable assets since it furnishes a quicJc and ready source of suitable medium quality absorbent. The use of the horizontal retorts for the pro- duction of batohite at the Gas Defense plant,. Astoria^ L.T.,. provided a. source of charcoal at a time when the supply of nut shells had fallen to a minimum v Most of the sources- of cocoanut shel.l were beyond the limits of the United States and our supply was dependent upon water transportation. The shipping of the country was taxed to the limit, the shells were bulky and a loss of nearly BO^o occurred during- the treatment ». making it very difficult to meet the demand '.15r for ahell chareoal- To secure a supply of absorbent char- ooal from a material as available as anthracite coal proved to be a great help at this critical period. The batohite produced was used to meet the demands of the British as well as our own government. Mr. Bridgewater of this section aided Mr. Holton in the supervision of the work- IJEVELOPMEMT OP THE EXTERKALLY FIRED ROTARY PURMOE : I ieu t . J. Holton, of this section, was detailed to the Gas Defense Division at Astoria to develop an externally fired rotary furnace. It was suggested that a rotary furnace could be used to activate charcoals. Such a furnace would produce a uniform product, and be continuous in action. The first step was to obtain the use of No. 2 American Gas Furnace containing a rotating tube 7'i-" inside diameter and about 4 ft. long. This was used with inter- mittent charges and provided with various possible types of steam jets and distributing systems. In this furnace, it was possible to activate cocoanut charcoal to 30 min. or more in about an hour. This work proved so promising that a commerical size unit was designed. Against considerable opposition, the representative from this section insisted that the steam be admitted under the charcoal and thus pass up and out, driving out the waftte gases instead of merely -16- playing over the surface of the charge. This was later proven to be an essential cpnsideration in producing the highest quality of Mate rial* All details were soon drawn up and aonstruetion started. The base of the furnace rested on a steel cradle made of t beams resti&g on two concrete supports 10 feet apairt-, the cradle being hinged on one support, thus allowing the slope of the furnace to be varied as desired. It either end of the cradle, there were two rollers, supporting two heavy tires attached to the. l^rge rotary tube. This tube was a nichrome casting, 13 ft. -6 in. long and 15 in. insid-e diameter with about 11 feet span between tires. Fastened to this tube was a sprocket chain driven from a worm and gear which in turn took its power from the main line shaft-, in order to secure continuous rotation of the tube at all times> a separate electric drive was provided to be immedi- ately shifted Into use when -the main power failed, besides a hand crank attached directly to the worm and gear- In this way there was but little chanse for the tube remaining stationary while hot. and thus sag or get out of true.. -Around this tube was built the fire brick combustion chamber arched over at the topL, and gas fired from rows of j'ets at either side, which were fed from four Premix Burners. It was found necessary, to conserve heat, to further lag the outside of the furnace with asbestos boiler covering. Suffi- cient -insulating brick was not used due to the excessive -17- weight ,, whialif wotild: h&ve' been put upon the oradle . The ends of the tub© were provided with charging and diarcharg- ing devioes»whiah, 'While somewhat clumsy, were successful in operation and prevented the great delay caused by wait- ing for castings and parts to make the large glands which were to be used in the final layout. The charging device consisted of a hopper fastened to and rotating with the tube, Which permitted itself to be charged, -while vertical during one revolution and then during the next revolution it discharged into the furnace. The discharge device worked similarly i- but in the reverse order* The steaM distributing device consisted of a two inch niohrome tube running the full length through the axis of the tube, en- larged at one end to 4 inijhes and provided with an opening to allow the waste gases to pass out. At three inch in- tervals along the two inch diameter section, half inch jets were provided,, extending within one inch of: the wall of the tube, and perforated at the ends. A steam superheater was also designed and built for this furnace with a capcity of 400 lbs., of steam per hour at 5OO°0. Thus the raw car- bonized material was charged at one end, and discharged at the other, the total slope being 4 inches in 10 feet. While passing through the tube, it was heated to 950O-1000Oc. and submitted, to the action of steam at the same temperature. The oohstaftt rolling^., tumbling,, and mixing gave almost ideal -le- oonditions for the activation of the material, and a capaQlty far exceeding the old stationary type of treaters was aeoiired. After continued use, the steam tube sagged slightly allowing the jets to wear on the bottom of the tube and the perforations to clog up. However » cutting off the jets about l|- in» and leaving a i- in« open hole, gave just as good aotivation and insured better operation » At this time the representative from this section was called away to other work, and so was unable to con- tinue his experimentation, but the work was continued by others, with remarkable results* It was found possible to produce coooanut charcoal test ing 45 min» to 55 min. (accelerated chloropiorin) at the rate of 50 lbs. an hour. This was more than twice the production and three or four times the qtuality of the charcoal msuiufacjhared in the old stationary Dorsite Treaters. The uniformity of product is far greater than with the stationary type,, due to the thorough tumbling and mixing. The development has contin- ued improving many of the construction details and increas- ing production by increasing the heated zone, but maintain- ing the same high quality. This furnace stands to-day as the best activating furnace known, which has been tried out and proved successful. IKTERHALLy FIEEP R OTARY STEAM THEATER .: Lieut. Holton was called from the work in connection with the externally fired -19- rotary furnaoe to aid the testing and development of an internally fired rotary furnace. Cement kilms at a oement plant in Egypt were secured by the government for this experimental work. Gapt. Seaman and iieut. Hoi ten worked together in laying out an experimental schedule. The rate of feed, steam rate, oper- ating temperature, and heating system were given careful attention. After a systematic investigation of the vari- ables, a schedule that gave good results with oocoanmt shell was established. From Egypt, Lieut. Holten was sent to the Hesearch Division at the National Carbon Company, Cleveland, Ohio. Here he was placed in charge of a de- tachment of m©n who were investigating new sources of acti- vated charcoals and studying the process of activation. Mr. H. K. Batchelor of the JUational Carbon Company directed the research. 7ery satisfactory progress had been made, both in the production of high grade coals and in the study of the mechanism of the activation. This work was so promising that it was continued for some time after the war. -20- ^MOKES FELT SMOKE fflLTERS : When the Germans began to use di- phenylahlor oar sine as an offensive smoke, it was evident that the American gas mask must be improved by the addition of a filter which would satisfactorily remove this and other irritating smokes. An investigation was commenced by lieuts. Abraros and Spofford, working at the Mass. In- stitute of Technology, on a large number of materials, in- cluding woven cotton, woolen, and silk goods, and felted woolen goods; powdered metals, diatomaceous earth, powder- ed charcoal; blotting papers, "puffed" paper, impregnated papers; porous metal, earthen and alundum plates; and leathers of all kinds. The sulfuric acid method was used in testing these materials, both on smoke penetration and on clogging. After a large number of tests had been made, the following three substaiices seemed to offer the most promising field: leathers (particularly chamois skins) , papers, and felts. It soon became obvious that leathers were unsuitable because of the variability in texture. Paper, in this stage of development, was fairly good, but felts seemed distinctly superior to any other material. A "Series of fexperiioibnts was now ^indertaken In connection with the itoerican Pelt Oompany and later with the Lowell Felt Obmpainy. These investigations covered a large number of factors, sach as the following: (a) Blend- ing and treatment of wools; fb) effect on felts of manu- faoturing processes, inoludfng fulling^ sp&oking,^ and buf- fing; (o) shaping of felts fdr filters. As a result of these tests it was possible to outline a method by whioh felt for smoke filters could be satisfactorily made. Most of the leading felt manufacturers of the country were now called into conference, and» after sufficient preliminary trials^ were able to produce felts which would meet the re- quirements for smoke filters* At this point the mechanical arrangement of the filter was ipade the subject of an .investigation. The intern- al wrapped canister, the flat plate filter, and the accordion filter were under consideration for a long time. From the beginning, however, the flat plate filter seemed to afford the most promising outlook, both on account of the simpli- city of design and the security against leakage. Large scale production of felt for smoke filters was undertaken by the Gas Defense Division after they had carefully surveyed the situation on wool procurement and on the capacity of the felt mills throughout the country. Throughout the development period, and in the early stages of large scale production, this section erected and operated sulphuric acid testing machines. It is vevy largely due to this control work that felt was satisfactorily -22- produced for smoke filters. tMVESTfGATIQMS.QP SULPHUBIO AQID SMOKE : When this section undertook the development of a smoke filter, it became necessary to formulate a method for testing filters. The research on sucli a smoke was begun by Lieuts* Abrams and Spofford in the laboratories of Mass. Institute of Techno- logy, using SOg as the smoke -producing substance. The quantitative absorption of smoke particles had not been worked out at that time, so that all of the testing had to be done either in a qtialitative way or by the Tyndall-effeot method. A crude testing apparatus was installed wherein sulphuric acid smoke was generated hy mixing measured amounts of humidified air and of dry air saturated with SO5 vapor- The resultant smoke was passed "into a' chamber whence it could be breathed through smoke filters. The demand for a quantitative method to use in measuring smoke concentrations and filter penetrations be- came so great that an exhaustive /search was made to find a way of completely absorbing this, as well as other smokes. It was finally demonstrated that coarse alundum thimbles were admirably suited to all this work, since when smoke- filled air was bubbled through these thimbles, immersed in the proper solution, complete absorption of the smoke took place* A testingmethod was at once evolved whereby filters -ES- could be ex{>0SQd to a sialphurio aoid smdlcis of definite oon- eentration* and the amount of penetration could be quanti- tatively determined i The clogging action of sUlphutlc acid smoke was also used to measure the qualit^^ of a filter. A great part of the development work on felt and paper filters is due to the evolution of the sulphuric acid testing method. In view of the fact that this method was to be widely used in factory testing of felts, it became advisable to make a thorough study of all the factors and to establish a uniform method both of producing the smoke and of testing with the smoke. A portion of this work was done by the original authors of the test, but most of the experimentation was carried out by Lieut. Stevenson and Capt. Dickson. This research resulted iiii the production of a standard machine for producing sulphuric acid smoke, and of a standard method for testirig against this smoke. Lack of uniformity in smoke filters made it de- sirable to distinguish the weak spots. Lieut. Stevenson perfected a test wherein congo red paper was placed next the filters, and any sulphuric acid which penetrated the filter was registered on this paper. It was therefore not only easy to locate weak spots in the filter, but it was possible to distinguish between good and poor filters. "SUCKED 01" FAI>EB glXTER : Upon the introduction of smoke as an offeasive instrument by the Germans, a search for a -24- filter was begun. The work was diT^ided into two fields: (1) The investigation of cellulose fihers» and (2) the in* vestigation of wool fibers, ^ile a few very promising paper filters had been developed none met all the speci- fications, - protection at low resistance, reproducibility, adaptability to large scale production, and capability to stand up under field conditions. The most promising cellu- lose fiber filter (the "suoked-on" filter) was developed by this section and the Mechanical flesearch and Development Section at the A> D. Little Oompany, Cambridge, Mass. This filter, made into the shape of the 1919 canister, and of a size to fit over the war-gas container, was prepared by sucking cotton-seed hull fiber from a water suspension onto a wire frame of the required size and shape. The first task in the development of this t^rpe of filter was to determine the optimum conditions of beat- ing the raw cotton- seed hull fiber, the optimum weight per unit area, and the density. An exhaustive investigation was o&TTDBi on with a special experimental filter, which permitted an individual study of each of the above factors. Having determined the physioal constants for the filters, the problem of machine control was taken up. Here the chief difficulty was to secure a sufficiently high density in packing the fibers* It was found that the factors which control density are consistency of stock fwhlch deter- mines also the time of forming), immersion of filter, and speed of rotation.. By oorreot adjustment, it was possible to just realize the minimum density, but to further increase the density, it became necessary to press the filter in a rubber bag, under a pressure of E5 lbs. per sq. in. The problem of drying the filter was thoroughly studied, and the results indicated that the temperature of drying was immaterial, but that it was necessary to dry the filter in a rigid form to prevent distortions due to shrink- age fwhich amounts to about 4%) . The matter of forming the filter with or without a wire support was solved in favor of the latter method. Under the propex conditions, filters were made which showed an eff ioieney of 96 » 5^ against tobacco smoke f85 liter rate), a penetration of les& than 5 p. p.m. by sulf»rjq a«>irJSTA RD GAS: This investigation was undertaken by J,ieut. T. M. Knowland in -31« an effort to produce a satisfactory packing material for filling up the space left open at the back of a horse 's hoof after the mustard hoot is strapped into position. For such packing, a material of very special physical and chem- ical characteristics is needed, and research was therefore directed toward the development of a cheap substitute for the old tar- oakum packing. A satisfactory packing has been developed with the following properties: It is plastic, capable of being easily rammed into position, and is easily scraped off when the boot is removed. The packing adheres firmly to the surfaces so that the plug cannot easily tear loose while the horse is working on rough or muddy ground. The packing has little tendency to flow or ooze after being rammed in- to position. It is not water soluble, and the viscosity is so great that in the event of contact with mustard gas, the rate of diffusion from the exposed surfaces upward to- ward the sensitive part of the hoof is negligible. The material consists of equal parts of rosin and rosin oil with sufficient asbestos wool to give the proper viscosity. This mixture is distinctly pliable at 0°C, but it is not too soft at comparatively high tempera- tures such as might be expected in ground exposed to the sun. The stiffness of the packing is determined by the percentage of asbestos wool, and it is possible to attain a high viscosity without altering the adhesive properties -58- of the mixture ► Use of the packing obviates the diffi- culties experienced with the old tar packing which soft- ened so greatly in the sun that the dissolved mustard gas was at once carried up into the cavity of the hoof* GAMOUPLAG IM G OF BLEASHIMG POWDER ; Reports from France in- dicated that it was desirable to camouflage bleaching, which was being used to destroy mustard gas in shell holes, since otherwise the enemy would be able to easily get the range of his guns. Extensive experiments with dyes and pigments were carried out under the direction of iieutc E.P.Stevenson, with the purpose of securing a material which would deceive the camera and the eye, would blend with all backgrounds, would be fast to chlorine, and would not catalyze decom- position of bleaching powder. It was finally determined that burnt umber alone (producing a brown tint) or mixed with small amounts of blue and yellow coloring matter f producing khaki tint), offered the most desirable coloring material. It was also demonstrated that these substances fulfilled most of the other requirements more satisfactorily than any other materials. Airplane tests were conducted by .tiieut. Abrams at elevations of 1500 and 5000 feet* The results showed that, whereas uncaraouflaged bleaching powder was plainly -g3- visible » both brownish and Ichaki oolored powder were quite successfully concealed from the eye and the camera at these elevations. PEBMEABILITY OP SOUP POTOER BOXES TO MU ST ARD GAS: In the early days of gas warfare as pursued by the Germans, it was customary to shell behind the lirles with poisonous gas- es for the purpose of contaminating- the food supply. With the development of gas ^ell and the use of mustard gas, the danger from this method of attack became very serious. The mustard gas vapors were extremely persistent, had a high degree of permeability, and w^re easily absorbed by many substances. The food supoly '6f out army, therefore, had to be protected by special methods of wrapping. In the field, one of the most easily prepared rations was made from "powdered s6up", a powder which was wrapped in oiled paper, enclosed ih a pasteboard box, which was again wrapped in paraffin paper- To test the permeabil- ity of this and similarly wrapped substances to mustard gas vapors » the material was removed from the box through" two small holes. Class tubes were inserted in these holes and sealed in place by paraffin. The entire box was placed in an outer box through «*iich air saturated with mustiard gas vapors was passed. A slow circulation of air was maintained inside the soup box, and the effluent gas was tested according to the standard -34- procedure. It. was found that in general, mustard gas woul-d not penetrate these boxes in less than 7|-" hours. The a- mount of mustsurd gas present would, therefore, not he at all harmful. In the aase food was heated before use, heat would drive off or decompose any of the gas absorbed.. Hence,, while the use of gas with the intention of hampering the food supply m%ht prove to be dangerous » proper preparation of the food containers would prevent any harmful effects upon the food* A PIEXB PFTEGTOB gOS HTUSTARD GAS : AH gases have charac- ter istia odors, some more distinct than others. In low, although often in harmful, concentrations some gases give very little sign of their presence by their odor. With persistent gases, a harmful amount may be present for sev- eral days» and in dugouts and shell craters ^ lethal fumes may be present but unknown to the approaching soldiers. It is the duty of the gas officers and their men to explore and test the air ^id ground for the presence of toxic sub- stances* Mustard gas in particular, due to its persistence in. trenches, shell holes, and dugouts, has caused many casualties. Ground that had been saturated with mustard retained the gas for several days. In the development work for field testing methods, the chemical addition products of any possible reaction and the reaction of reduction -55- products of diohloroethyl sulphide were oonsidered. Color reactions gave promise of results and an electrical device for the decomposition and the subsequent reaction of these products gaye very satisfactory indica- tions. The air was drawn from over the surface of the con- taminated earth, or from the air of a dugout, by an ex- tension hose attached to the canister. This device, which was simple and compact, was plaoed between the hose and the canister. The canister protected- the man from any gases not destroyed by the detector,. THE OXOMETSR FILTER : The oxometer is a portable apparatus for producing oxygen gi^s frojn fused sodium peroxide. In producing oxygep, it was found that considerable quantities of caustic were carried over mechanically by the gas into the patients? lungs, and it was therefore necessary to in- troduce some type of filter to remove these particles. Experimental runs were made in which five differ- ent types of fabrics were tested as filtering media. A fabric was finally selected which would completely stop the passage of caustic particles for a period of. 40 minutes with an average pressure drop of l^ inches. The apparatus itself was so unsatisfactory in operation that the researoh finally concluded with an in- vestigation of improvements to be made in generating the o:xygen-^ -36- PRODUCTTIO H OP LENSES FOR EYEPIEOES: In producing the tri- plex lens for the eyepieces of the gas masks, numerous mechanical and chemical difficulties were encountered. This section was called in at various times to investigate and remedy these difficulties wherever possible. A large amount of this investigation was carried out "by Lieut. Mher and Mr. Boynton. For a long time the capacity of the Super-Glass Company had dropped to aa low as 20,000 eyepieces per day, with &0fo rejections. These rejeations were largely due to "let-goes" (in which case the glass separates from the pyralin layer )» cracks, "squeeze-outs", and dry spots. Most of these difficulties were caused by iasuffloient cur- ing of the pyralin, £«id by improper methods of cutting and pressing the layers used in the eyepieces* This seation suggested a large number of improve- ments, increasing the production of the plant from as low an average as 20,000 lenses per day with 60'^ rejections, to as high as 50,000 lenses per day with lO'^ rejections. AUTI-DIMMIMG MATERIALS : One of the chief drawbacks to the gas mask had been the dimming of the eyepieces. In both the old S.B.H. and the new Tissot types, the eyepieces fogged q.uiokly in cold weather. Many devices were suggested to remedy this de- fect, but most of them were not applicable to the masks al- ready in production. The passage of the entering air over -37- the surface of the eyepleoe, the use of transparent mater- ial other than glass, the separation of the upper section hy a dam, and the use of double layer eyepieces were suggested and tried. The passage of the air over the eye- pieces was perhaps the most satisfactory. In the old type masks, having the mouthpiece, the simplest method was to treat the glass eyepieces with a chemical which would prevent the precipitation of moisture in small droplets » but would keep an even film of water over the entire surface- Such material was developed by Dr. Spear and Mr* Stevenson of the Chemical Development Section, in con- junction with dapt, Garlton, and the Colgate Company. The material could be produced as a. thick paste in stick form, as a thin paste in tubes, or as a liquid. The stick or tube form was the most desirable. Special soaps with an excess of glycerine (to be rubbed over the surface and then wiped with a dry cloth) formed a film that tended to prevent the coagulation of droplet. The trouble was not entirely corrected, but the mixture employed gave clear vision for several hours, de- pending upon conditions of use. The method of application to tecure the best results was established and recommended. and all the masks were furnished with anti-dim, -38- HORSE MASK : A horse mask was developed, partioularly with the idea of improving the old type mask so that mustard gas would be absorbed satisfaotorily. The seoondary oon- sideration was that of lowering the resistance to breathing which in the old mask was sufficient to cause horses to collapse when laboring hard. Two bags were made up of cheesecloth in the gener- al shape of the old mask, one bag fitted within the other. The inner bag consisted of 4 plies of fabric, impregnated with the regular komplexene solution. The outer bag was made of 8 plies of cheesecloth and was impregnated with simplexene, which is a mixture of rosin, rosin oil, and paraffin oil. The proper composition of this mixture was determined in more than 200 experimental 1;ests. As to chemical protection, the new mask has held up satisfaotorily against saturated mustard gas vapof for 90 minutes or more at a rate of 50 liters per minute over the entire surface. This rate is comparable with a horse's breathing rate while at rest. The resistence of the mask at this rate is not measurable. Protection against chlorine, hydrocyanic acid, and phosgene, is superior to that of the old mask* The mechanical features of the mask were also im- proved, and actual field tests showed that this form of protection was worn by horses without any difficulty. -59- HORSE IviASE TESTS 013 GALYAMIZEB IRON QLIPS FOR USE OM THE HOR SE MAS K : A series of tests have been made at intervals to determine the effect of ageing on the galvanized clips used in the horse mask. Tests of pin holes and thickness of the coat- ing were not desired, but rather an idea of the results of prolonged contact with the hexamethylene tetramine used as a dope on the mask fabric « Samples of the clips were weighed and immersed in the hexamine solution, and oxidation was determined by difference in weight after long exposure to the solution. Accelerated ageing tests were also made where the clips were exposed to steam and air over a considerable period of time, and the difference in weight, caused by oxidation, was determined. These tests gave a fair idea of the purity of the zinc, - an important factor in its protective pro- perties* RUBBER IMVBSTIGATIOIiiS : Rubber in some form entered into most of the protective appliances used in gas warfare. The rubber investigations fell into two distinct classes : (1) chemical, and (2) mechanical. A unit with men from both the Ghemical and Mechanical Development Sections of the Research Division was organized to work in conjunction with the Goodyear Company in developing the forms and modi- fications of rubber or rubber impregnated material that would be required in the defense program. -40- The chemioal work was conneoted with different mixes^ cements, fillers, and oures. The mechanioal section considered the design and the physical properties of the product. The early work was devoted to gas mask fabric, the earlier types using an impregnated cloth, and the more recent types a gum with stockinette backing. The development of a horse mask resulted in two problems. The first was the stiffening of cloth strips by an inexpensive impregnation which would hold the bag of the mask open when in use. The second was a rubber or rubberized mouthpad for the masks. The mask is placed over the horse's nose, and the bottom of the bag is carried in the mouth. The pad is used to prevent the horse biting through the fabric, and to help keep the mask in position. The pad must be strong, flexible, and smooth, and due to the large number manufactured, the cost must be|reasonable. Both solid cheap stock pads and impregnated fiber pads were tested. A heavy jute webbing with a skin coating of rubber proved to give a very satisfactory pad. The flutter valve as first produced, while satis- factory, was open to improvement since the leakage was con- siderable and the valve was objectionably large. With the intention of improving the flutter valve, development re- sulted in the production of an arch type flutter valve -41- whioh was entirely enclosed in a brass oasing with only the necessary air porta* The valve consisted of two arohed Girctilar discs- It was compact and mechanically strong.. A great many trials u'ere necessary to secure the best mix for these dlscs^ They must hold their shape perfectly, and yet be elastic and of easy action to avoid high resistance.. The development of the felt filter brought up the problem of securing a gas tight ^oint between the edge« of the felt* Sewing, rubber tapes., and various kinds of dope were tried. The most satisfactory solution was the vulcanization of the edges, using cement between the edges with a gum strip binding* Specially cured gaskets or washers were studied to aid in making the nozzle flange gas tight. As a protection against water, a waterproof cover was developed whioh was vulcanized to the edges of felt layers, at the same time the layers were cured. Weed- less to say, raamy cements and trials were necessary before a satisfactory joint was obtained. The signing of the armistice stopped further development on all these problems^ Q0MPABATI7E FIgJLP TESTS OK THE EFFECT OP RESISTAIGE AM? DEAD A IB SPASE ; This series of tests was designed to give a qualitative idea of the effect of resistance and dead air space. The same test was run with (1) the complete mask, f£) the mask without the faoepiece (canister, mouthpiece, «4E- and noseclip only) and (2) the same as (Z) except that an extra volume about equal to the dead air spaoe in a Tissot mask was inserted between the flutter valve and the mouth- piece. As a result of these tests and some other tests previously made, it was concluded: (1) That resistancse, up to at least the amount of exertion involved in a 4 mi- per hour walk, was not a signi- ficant factor compared with other faults of the present mask. (2) It was inferred that resistance became of prime importance when a sudden burst of energy was made, and the body demanded the maximum possible supply of air ("running until exhausted). (3) There was apparently a noticeable but slight effect due to dead^air space under the rate of breathing while at rest. (4) Under the rate of breathing involved in a 4 mi. per hour walk^ there was no noticeable effect ascribable to dead-air space « (5) The chief defect of the mask at that time was pressure on the head by the head-harness, resulting in a serious loss in morale and in physical disability. (6) Less important causes of discomfort of like nature were fatigue from wearing the noseclip and in retain- ing the mouthpiece in position. Vision was not as good as -43- oould be desired, and in close fighting or certain kinds of work, might have Taeoorae a serious disadvantage* PHYS IOLOGIO AL STUDY OF THE G A S MASK : The demand for gas protection during the early stages of the war was so urgent that very little time oould be given to the consideration of the best design with respect to the effect upon the wearer. The one idea was to secure protection and an im- mediate supply of masks. It was soon found, however, that an excessive resistance to the' flow of air so exhausted the soldier that he would become valueless in fighting. Experiments were then started to determine the relation between reastance and protection. The studies of the resistance in the vari- ous mask parts led to changes in design which gave much greater comfort to the wearer, fiesearch on the reastance of the inlet and outlet valves and its effect on the mask leakage and comfort brought many weaknesses of the earlier types of mask that- could readily be remedied. This work was done under the supervision of Dr. W.K. Lewis, while leading physiologists were called into consultation. The greater part of the theoretical work was conducted by Dr. Pearoe, assisted by Oapt. 3eiman of this section, at the Lakeside Hospital, Cleveland, Ohio. With the adoption of the Tissot type facepiece , work was started on "dead air" space, and its effect upon -44- the waarer. The Investigation covered the resistance of all parts, the amount of "dead air" spaoe, the leakage, the inhalation and exl-ialatipn pressures, and volumes for different men under various conditions of activity, the fit of the mask, and the adjustment and types of head harness. Every point of the outfit was given careful consideration with the idea of perfecting the new mask so that it would cause minimum discomfort to the wearer, and yet afford ad- equate protection- THE IKDUSTRIAL GAS MASK : The use of a mask for protection against war gases led to numerous inquiries for similar protection against gases encountered in industrial practice. Requests had been received for masks to comhat hydrogen sxilphide, chlorine, carbon monoxide, sulphuric acid fumes, sulphur chloride, nitric oxide, ammonia, benzol, titanium tetrachloride and others. A policy was outlined whereby suitable rejects from the American gas mask would be used in conjunction with standard canisters filled as follows: Type A All charcoal Type B All soda lime Type C QOfo charcoal - 40^^ soda lime Type D Pumice impregnated with copper salts (ammonia canister) Type E HO foarbon monoxide canister) The absorbents were to be made up according to the specifications furnished by the Research Division and -45- canister paoking was also to be done on speoifioations. The finished aanisters were to be tested against gases encountered in industrial praotioe, and the Research Division was then to specify the proper type of oan to be used in any factory. Protection against most industrial smokes was to be given by cotton pads in the canister. Whersr^xr necessary, flat plate felt filters were to be specified. These tentative arrangements were being put in- to execution when information was received that the He- search Division would not be permitted to apr^rove of in- dustrial masks; that all information pertaining to these masks should be gathered together and published in techni- cal journals; and that, thereafter, any concern could make and issue such masks. -46- HYDROSEU PRODUCTION OF HYDROGER ; In June, 1917, it was learned that the government planned to build and operate hydrogen gas plants, employing the iron contact process. As this process was new and had been little used, Dr. V/.K. Lewis di&cided to train men to serve with the Navy and Signal Corps" in superintending the construction and operation of these plants. Consequently, J» H. Holton was sent to the Goodyear Tire and lubber Company to study the process at their plant near Akron, Ohio, where Goodyear also maintained a large balloon testing station and flying field. Holton remained at the plant for about five months, and became tlQroughly familiar with all "the details, then went to Pensacola, Fla., and Atlanta, Ga.. , to study plants of the same type as it was planned to build at Langley Field, Hampton, Ya. In January, 1918, Holton visited Langley Field, and found that plant in the process of construction, but far from completion. A report on this trip was made to Lieut. Col. Geiger of the Balloon Training Section, Signal Corps. It was later decided to permanently detail another man, Corp. w. F. Tilton of this section, to the Hampton plant, so that he could be on the ground to supervise and inspect the technical construction. Once a month Holton visited the plant and went over the progress of the work. -47- >OBOUS IRQ II ORE PRODUCED B Y A H S M ti. B E T T S, /. 8 H V I U L L, 12441 PROrUOTIOM OF HYDROGEN '^"fe::^ :■ C ■ U 3 IRON ORE PRODUCED h 'i SOL'THEPK LEASING CORP CARTfeRflVILLL, G A . POROUS IRDB ORE Ho . Z PRODUCED BV WOODWARD IROK cr WCOEWARD. ALA. POROUS IRON ORE NO. PRODUCED hi WOODWARD IHOti CO. irCOCPARD AL/> 1246 PRODUCT lOI^ OF HYDROGEN It was, the duty of these men to furnish the plant with necessary offibe equipment and suptjlies of ooke, ooal» end wood. Many questions came up during the construction, such as the use of waterproofing cement* irregularities in high pressure piping, and other specifications upon which recommendations were to be made. Both representatives dis- couraged the idea of using the hydrogen plant as a gas plant to furnish heat and light for the field. When finally the plant reached the stage where gas could be made, a sufficient number of men was detailed to learn the operation of this plant. Just before their training was cOTipleted, an explosion occurred which wrecked the blue water. gas meter, and caused another delay of about si-x weeks. The contractor again announced that the plant was ready for operation, and this time a permanent detail of men was sent from Port Omaha to carry on the work. As before, these men were trained by the contractor until they were ready to run the official acceptance test under the direction of the contractor. The Constructing Quarter- master directed the test to be run under the supervision of the representatives from the Chemical Warfare Service. T^is test proved to be unsatisfactory, and was later con- sidered void. A second test was run in the presence of a number of officers of the Signal CJorps of the Army as well as the Ghemioal Warfare Service representatives. This time the plant passed satisfactorily all requirements as to -48- t^. , f i; t » USE r <^ " OF H ■/ fc P. ' f • TACT PRnCIi ^.. •:,> ^'^ ... T p. K C tJ ■ 1246 PRODUCT lOfl OF HYDROGM oapacity and purity. Holton was then asked to serve on the Official Aoceptan'ee Board, which was to receive the plant from the soil tractor and turn it over to the Balloon Section of the Department of Military Aeronautics. This Board met in the latter part of August,. and took the plant over for the government, presenting the contractor with a list of exceptions and unfinished work, and giving him until September 16th to reply. At that time the plant was form- ally turned over to the Balloon Section.. The plant was left in the hands of the officer- in- charge, with a trained staff of operators^ and later a complete report was presented. A report was also presented on treatment and sources of porous iron ore for use in the plant. -49- HOPQALITE PRODUCTION OF HQPQALITE: This section was designated to worlc with the Defense Ghemical Research Section, to learn the method of making hopoalit© (the new carbon monoxide absorbent), and finally to be responsible for manufacturing hopcalite on a large scale. Small scale production was first carried out in Washington, with the assistance of Corp. B.T. Rauber. A thorough study of the important factors furnished the necessary data on methods of precipitating the oxides of cobalt, manganese, copper and silver. Information on filtration, pressing, drying, and grinding the oxides involved extensive work, but the necessary equipment was secured and the essential research was furnished in a short time. The Navy had requested sufficient hopcalite to fill 50,000 canisters at the earliest possible moment. A contract was drawn up with the Rare Metal Products Company, Belleville, K.J., whereby they were to furnish all equipment and materials for large scale production, while the Defense Chemical Research Section would out- line the experimental procedure, and our own section would then control the large scale production of hopcalite. -50- The plant was aonstruoted in record time. Chem- icals were procured, equipment was installed, and the first batches were laid down according to specifications. The inevitable difficulties, in passing from small scale to large scale production, were encountered and were solved by the men in charge. Filtering, pressing, drying, and grinding equipment was designed and installed. The production of hopoalite was then carried on by this section to completion of the contract. This section also assisted in securing a satisfactory supTJly of calcium chloride to be used in driers for the hopcalite canisters. BEU20L. TOLU OL. A MD XYLOL IN GAS TAB IKTEBMEDIATESr Because the presence of cyclic saturated hydrocarbons influences the boiling point of the benzol series far out of propor- tion to the quantity of substance present, an investigation was instituted to determihe a method of purification so that the boiling point might be used as an index of the aromatic constituents* The literature on this subject was studied, and the most promising suggestion was the sulfonation of the aromatic hydrocarbons and their subsequent hydrolysis. The method, with its variations and limitations, was stud- ied, and a schedule was determined which gave the mos^ satisfactory separation.. -51- The recovery did not prove to be quantitative, due to the loss of vapor and the formation of sulfones and carbonaceous residues. However, the losses appeared to be proportional to the amount of aromatic hydrocarbons present, and the purified liquids showed noimal boiling points. This method, while being far .from perfect from an analytical poimt of view, offered one of the most rapid and accurate schemes for the analysis of the im- portant aromatic hydrocarbons, benzol, toluol, and xylol in the presence of saturated aliphatic compounds. -52- TESTING METHODS ST AMPARDIZA TION OF TESTING MTHODS ; The first work done by Capt. Diokson was the standardization of testing me'thods, and this work was prosecuted continuously on testing machines in many of the laboratories. After visiting these labor- atories, a report was submitted which included a ballot covering the chief points requiring standardization. A conference was held in Washington at which decisions were reached on these points and rhich, in a general way, guided subsequent standardizations. At this conference a co- ordinating committee was appointed to pass upon methods for official adoption. The tests which were of the most importance or which have most required standardization, have been written up and approved by the committee, and issued as standard methods. Some methods have been written up in collaboration with the laboratory originating the test with a view to later standardization. In connection with this coordinating work, the laboratories were visited frequently in order to as- certain whether the standard methods were being followed. and to suggest improvements, to keep in touch with new methods^ to select the best modifications for standardi- zation, etc. -5&- In aonjunotion with the oommittee on Field Tests at the University, active worlc was done in planning stand- ard tests on gas masks to bring out the relative values of different factors* Work was carried out in developing a smoke test (sulfuric acid), adapted to control testing in felt mills, in supplying standard apparatus, and in organizing control tests on the different machines. The nature of the chief work was such that oppor- tunity was presented for a large amount of miscellaneous liaison and consultation work, which, although rather in- tangible as to results, proved to he of value and importance The following standard methods were issued: General Analytical Methods. Standard Tube Test with Chlorine. Standard Long Ghloropicrin Method. Accelerated Ghloropicrin Method. Standard Phosgene Standard Superpalite Tube Test. Standard Hydrocyanic Acid Method. Standard Tube Tests with Arsine. Standard Cyanogen chloride Tube Test. Standard SOg Tube Test. Standard Method for Screen Analysis. Standard Pressure Drop. Standard Detonation for Man-House Tests with Diphenylchloro arsine . Standard Flange Tests for Smoke Filter with Sulfuric Acid. Standard Flange and Canister Tests of Smoke Filters against Tobacco Smoke. Discussion of Harness Testing. -54- ISEW GASES . PROTEQ'TIQU AQ AIMST ME W GASES : Buring the early stages of poisonous gas development, many emergency problems were suggested regarding the protection offered against new gases. At the time the information was required ^ ho stand- ard methods of testing had been prepared, and the investi- gator had to devise a scheme for testing and interpreting the results. In some cases, the value of charcoal and soda lime for absorbing or destroying a gas had to be determined; in other the protection afforded by different fabrics had to be established. In the early part of 1918, the value of charcoal and soda lime as a protection against mustard gas, xylyl bromide, and cacodyl chloride was studied. Analytical methods for quantitative determinations of the concentra- tions, and a method of determining the break points were developed and used. Special absorption apparatus had to be constructed for each case due to the different physical properties of the different gases. A large amount of this work was done in Philadelphia at the plant of the United Gas Improvement Oompany by Mr. E. R. Bridgewater. With the development of vesicant gases, protective devices had to be designed that would keep the defense program ap^ce with the offense work. The effect of new gases, chiefly forms of mustard and lewisite, on both the -55- existing devices and on all new material, was studied and recommendations on the necessary changes or new develop- ments were made. As in the earlier tests, both the form of apparatus and testing procedure were developed for the work Some of the important deyelopments dependent upon this work, were the dugout blanket, horse mask, and pro- tective clothing. SOLUTION OF SASSS TM SUBPH^TC ACID SMOKE : The use of sul- furic acid smoke xb felt testing demonstrated that it was very penetrating but had little irritating power. It seemaa , however, that some toxic gases might dissolve in this smoke. Preliminary work was carried out at the Massachusetts Ih- stttute of Technology by lieuts. Spofford wai, Ahrams, but the resultant qualitative tests indicated, that chloropicrin, phosgene ^. and chlorine were but littl« dissolved. Further experimentation and a study of the factors involved in such solution, were carried out under the di- rection of Mr.^ Stevenson. His results also demonstrated the facjt it would be impossible to dissolve sufficient quantities of toxio gases in the sulfuric acid smoke to be of any considerable value in offense operations. DISTRIBUTIQH OF QHLORIHE IM GASSED QAJJ IS TER S: Canisters were gassed with phosgene as on a usual test, and then ,~^ samples of the absorbent filling were carefully removed from known locations in the oanister where it was suspected that the insertion of special baffles might increase the utilization of the absorbent. These samples were then quantitatively analyzed for chlorine. The percentages of chlorine were indicated on a drawing of the special can- ister so as to give a graphical idea of the distribution of the gas in relation to the structure of the canister. rt was found that (1) ring baffles were of some value in bregiking up channeling near the sides, (2) that center baffles were of doubtful utility, and if used at all, should be perforated; otherwise the absorbent immediately over the center of a solid baffle was relatively useless, and (Z) that wave- front method could not replace the present method in deciding upon the merits of special designsi since the former was qualitative while a quantitative study had to be used to determine the relative utility of differ- ent portions of the absorbent. IMTERMITTEMT FLOWt/IETERS; In oanister testing, it was de- sirable to reproduce as closely as possible the human breathing rates- Special mechanisms were developed which gave intermittent flow that very closely corresponded to the actual breathing rates. To secure these conditions, complicated mechanical valves and pumps were used. In an endeavor to simplify the apparatus and to provide an easily portable set for intermittent canister testing, an auto- -57- matiG water flowmeter was developed. It consisted of a U tube with a by-pass connecting the lower arm of one side with the upper a3*ra of the other side* As air pressure was apTslied to the sjide with low by-pass connection, the water column was forced down and below the by^pass opening un- til sufficient pressure was built up to force water out of the by-pass* Air flowed through the by-pass until out off by the returning water. A very careful study of sizes of pipes, valves, and air chambers was necessary to secure Q form that would function properly. A further study would, however, be required before specifications could be drawn up for the construction of 6 machine which would give any rate cycles per minute, and percentage time &f inhalation and exhalation. This work was undertaken at the suggestion of John B. Dickson^ and the work already done was carried out under his direction. -58- MISOBILAKEOUS IHVESTISATIONS : In the work of the Chemicial Development Section, many problems were started and turned over to other organiEatlons when the fundamental principles had been determined. In other oases, work was started in con June tion with other departments. After a short prelim- inary study of the chemical nature of the problem, the balance of the work and mechanical design would be worked out by a division dealing with that type of problem. A large amount of work was done in control testing and in technical advising of other departments. A few of the minor problems handled in this way are listed here for reference: 1. The testing of adhesive tapes used in mend- ing gas masks fabrics. 2. Testing double loop noseolips.. 3» The path of diphenylchloroarsine through the felt filter. 4. Special research on diphenylchloroarsine testing methods. 5. Corrosion tests on metal hooks and buckles. 6. The ageing of elaatic webbing. 7. The effect of simplexene and komplexene on elastic webbing. 8. The strength and physical properties of pyralin for gas mask eyepieces. 9. The design of experimental rb'tary steam activating furnaces for charcoal. -59- In all development work, this section allowed its men to remain with the work until new men were well trained i Often this section transferred some of its best men to take charge of the actual operations, thus insuring the success of the undertaking after it had been taken over by the Manufacturing Division. -60- WAR DEPARTMENT CHMICAL WARFARE SSRVXCE RESEARCH DIVISION AMERICAN UNIVERSITY EXPERIMENT STATIOH MSHIJJGTON, D. C. MAJOR GENERAL W. L. SIBERT, DIRECTOR COLONEL G. A. BURRELL. CHIEF OF RESEARCH DIVISION MECHANICAL RESEARCH AND DEVELOPMENT SECTION B. B. FOGLER. IN CHARGE SUMMARY OF ACHISVEMEUTS 1917 - 1918. M3CHMIGAL RESEARCH AMD D^VELQPMSNT SflOTIOM HISTORICAL This group was organized as a unit on September 4, 1917, under the direction of Mr. H.H. Clark* who was trans- ferred froin the Pittsburgh Station of the Bureau of Mines to take charge of the work. The demand for this unit arose from the fact that whije the primary research on the majority of problems connected with; gas warfare is chemical, the most of the devices developed for this purpose require a properly designed physical housing before they can be successfully put into field servMe. This group was created to meet this need by working in cooperation with the various chemical re- search groups which then existed or we^-e later created in connection with this gea€(rai research work. A,S originally oi'ganized, the unit consisted of two main si|b-div4.sioOB, - first, a group of research mechanical engi- neers and their assistants who were provided with office and laboratory space for properly carrying out their work; second, an instrument shop eq\J.ipped to fabricate the various designs developed Ijy tjie enjgtneera in the first group. The problems -^QBHSa^g to this grpup ,j|iight be p;).aced under five main headings: -61- vl) The development' of devibes us«d' for the army as defensive equipment in gas warfare. (2) The development of d^vioes used, by the army, as offen- sive equipment in gas warfare »- (3) Gas defense equipment riequired by the navy. (4) .Equipment required: by the navy in, connection with the various pyrotechnic signal: devices upon which thirS Station did a large amount of research work- (5) Miscellaneous* problems connected with the design of special mechanical apparatus for use in the various labora- tories throughout the- Station. The organisation continued along these lines until May 4, 1918 ». when the volafloe of work necessitated a sub- division o;C the work under which the group of men working on army defense problems was separated from the rest of the section and r>ut iznder the charge of Mr. ^^.B,. Foglei", the .„..: balance of the section remaining under the direction of Mr. H.H. .Gl^rk.. On June 25th^, the entire personnel of the group known as the War Gas Investigations of the jiureau of Mines was transferred to the War Pepartmentj and became the Research Division of the Chemical Warfare Service. This- transfer was made in conaection witii a c'-^mplete peorganiaaiion of the . various grolitss iA^orklng- on different problems of gas warfare, but had little effect &n the internal work of the various ^2- sub-divisio»« a|;Vt:[i@ .American University, except that it was the beginiiin^/of the more complete militarization of the personnel erigagftd in this work. On August Si 1918, the mechanical work at the Station was aglELih reorganized. In this change all the work of a research nature boy^h for the army and navy was placed in charge of Mr. B.S. Fogler, while the instrument shop and a part of this draftsmen engaged in miscellaneous service work were transferred to the service unit of the Administrative Section under Mr. Richmond Levering. In view of the fact that the mechanical research work for the enti-re Station began and ended in a single group, this final progress report will cover the various research activities along this line carried on since the beginning of the work on September 4, 1917. Wo attempt will be made to correlate, except in a general way, the problems and the personnel engaged upon them, as these will be found in detail in the indivlduakl reports on the various problems to be found in the files of this section. ARMY.-JBFEgSE PRQBLa^ AIMY MASK . Very naturally, ©ne of the chief j^Toblems under- taken by this grouf "wgs tij« development and refinement of the army 'gas toask. In considering the large amount of work dTone on this probl®a^.a;~ logical sub-division may be made be- tween the facepirece .fliid tite: canister, for the reason that . -62- with the possible exception of the type in which the absorb- ent is an actual unit with the facepiece, as is the case with the French "M2" mask, or practically a unit, as exemplified in the German mask, neither of which played any great part in the defense research of this country, the various types of facepiece and canister are interchangeable with one another. Army Pacepieces Box j:teapirator . The standard box respirator mask produced by the Gas Pefense Division was modeled very closely after the English mask. For this reason, the work of this Station on the development of the facepiece consisted principally in improvements in the details of construction and the devel- opment of a suitable mask fabric. The problem of the noseclip, spring and pad, and their location in the mask was carefully worked out. A rubber pad shaped like an inverted cone was designed which is a marked improvement over the British type. The spring itself was studied and an instrument developed for measuring the pres- sure exerted by the spring against the nose. An iBjproved design for the die casting, which gives a lower resistance* was submitted to the Gas Defense, but was not adopted. Considerable work was also, done to improve the vision of the eyepieces* resulting in the adoption of triplex glass and an efficient non-dimming mixture. -64- BEITISH BOX RESPIRATOR SHOVilHG COTTON WRAPPED NOSS CLIPS MERIGAN BOI RESPIEATOR SHOWMG IMPROVED HTJ3BER K0S3 CLIPS 1084 NOSE STOPPBE FOEJNSGfiO 30LDISRS Interior view of the mask vvith uose stopper in place. NOSE STOPPER FOE NEGRO SOLDIERS Pad and harness removed from the mask and fastened in place on negro to show the position assumed "oy the stopper when in service. Side View 1085 N0S3 STOPPER ?0E NSHRO SOLDI 3KS Pad and harness removed from the mask and fastened iji place on negro to show the position assumed by the stopper when in service. Front- View The question of a suitable fabric for the facepiece was taken up by the Gas Mask Research Section. Suitable methods for testing the resistance of various fabrics to penetration by gases were developed and standardized, A great variety of fabrics were tested and a high grade rubber coated fabric" found to be most suitable. ^ erican Ma sk of "M2" Type . During the latter part of 1917, designs were drawn up and several hundred esqperimental masks manufactured along the same lines as the Frepch "MS" mask, in which the lower part of the facepiece consists of a pad Q^ several layers of cheesecloth containing an absorbent im- pregnation. The adoption by the aripy, however, of the box respirator type,, together with the promising features of the development work then being carried on in the direction of the Tissot type, led to the abandonment of any further work along these lines. Tissot Type . In October 1917^ the first American Tissot type mask was made by the Mechanical Section of this Station* assisted by I>r-. Gre«r of the Goodrich Ruboer Company. It is designed on the principle of the French Artillery mask. The facepiece is made by cementing two pieces of red rubber to- gether. The seam extends directly down the front of the mask and under the chin-. A narrow reinforcing strap of the same material is put around ^e edge of the mask to form the eye- piece frames. -65- MSEICAIJ ilASZ "M2" TYP3 Copied from iTrenon iviask. The protection afforded by this type of mast depends oja a tight seal between the rubber and the face, the wearer breathing in the natural manner through the nose and mouth. The incoming air is led through Y-shaped rubber clarifying tubes inside the mask, so that it strikes the lenses, clear- ing them of condensed moisture. The e^aled air passes out through a flutter valve of English design protected by a guard of sheet aluminum. The eyepiece frames are similar to those used in the French Fabric mask, being held in place by lugs which are bent under the glass. The chin rest is made of aluminum and covered with a section of rubber tubing. The angle tube is designed as a casting, but is hand-made, embodying all the principles of the present Tissot type die casting. The head harness is made of strips of soft rubber so arranged that tvo straps pass around the back of the head while a third connects these two with the top of the mask in front. B.M- Tissot. The Bureau of kines Tissot, as it is commonly I H I W ■■■■■» H MI I I ■ I ■ »l !■ known, is a further development of the original mask described above, ant represents the development between October 1917, and April 1918, when the mask was tuiTied over to the Gas Defense Division to be put into production. The facepiece is made of two layers of calendered stock, an inner layer of soft, elastic rubber, and an outer protective layer of tough black stock. It is cured on an aluminum form, which gives a -66- AMERICAN TISSO'J? TYPJi kiASK Side View. AlilERICAM TISSOT TYPE kASZ Interior View AMERICAN TISSOT TYP3 MASK Die casting with chin rest» inhalation (clarifying) tubes, exhalation flutter valve and guard, and breathing tube which Gcnnects with canister, assembled in position. smooth -finished intefiorv-an^ causes the mask to fit the face tightly axottad th& bonders, and yet clear the nose in front- The eyepiece frame is molded separately, and cemented to the facepi^ce in a &emi-cured condition. The facepiece is then put on the foraier, the head-harness of rubber straps attached ,. and the whole cured in one operation in dry steam.- The clarifying tubes and chin rest are of molded rub- ber and assembled at the same time as the die casting and eye- piece frames. The clarifying tubes are the same design used at present, -and deliver the incoming air directly against the eyepiece lenses* The chin rest is made with" rather long horns so as to hold the mask firmly in place. The present Akron Tissot is a further development of the B.u,. mask* The pi'incipal alterations are the stockinette covering foi* the facepiece which replaces the black protec- tive rubber, alterations in the aluminum form to give greater space between the mask and face* stiffening of the facepiece, and a head -harness of elastic webbing* Whittles&y Mask. In April.,. 1918,. Dr. Whittlesey of the U.S. Kubber Company developed the idea of applying a rubber coating to stockinette on a calender , -cutting oiit the facepiece, ce- menting the seam omder the chin, -and curing the ma^ik on a flat form of wood or metal* A nmiiber of these masks were made for -67- rtHITTLESJSY MASK One piece masii, seam undsr chin. DIPPED MASK One piece seamless mask, stockinette covered. this seetian soad -thoroiaghiy tested. It was foxrnd that while extremely light and comfortable., they developed a tendency to collaj)se around the ;nase., thns in1>erfexing with respira- tion. This di'fficulty was remedied to some extent by in- sertion of stiff reinforcing strips at the cheeks^ but the mask was never put into production.. The Dipped Mask >, A method for manufacturing the Tissat type mask by dipping the forms in-to a solution of rubber, was developed by the Ravenna iiufeber Go. in conjunction with the Mechanical Section, The facepi-ece of this mask was formed by dipping an aluminum form into a solution of a suitable rubber compound in naphtha. VVhen a sufficiently thick layer of rubber had been formed by successive dips, the rubber was covered with stockinette, a reinforcing strip placed around the edge, and the mask cured in dry steam. This process gave a well- finished process without seams. The method was turned over to the Gas Defense Division to be put into production. Howe Type Mask » A number of experimental masks were made by this Section at the Howe Hubber Company to determine the ad- visability of placing the stockinette inside of the masks. The masks were made of the Tissot type with the stockinette on both the inside and out^i^-e of the fac«piece, and as an intermediate layc^r. .An olive green, son -blooming rubber com- pound was used for the facepi«CB., eliminating the necessity of dyeing the stockinette* The mask with stockinette inside was reported very favorably on field test, the fabric being more comfortable than rubber against the face. Miller Type Mask . In April 1918 ^ a special Tissot type mask was produced by this Section which embodied several novel features. The inside clarifying tubes are eliminated. The inhaled air passes from the die casting, through an intake tube up the front of the mask and is introduced through the facepiece between the eyes^ It is directed against the lenses by a baffle of rubberc The inlet tube of the die casting is at right angles with the flutter valve and allows the flexible tube to be carried over the shoulder. This permits tipping the flutter valve and guard forward so that it will riot strike the chest when the head is lowered. Masks of this type were made up with both black rubber and stock- inette reinforcement. The mask was criticized because the attachment of the inhalation nozzle to the die casting on the outside of the facepiece necessitates two openings J.nto the mask and there- fore doubles the possibility of leakage. In order to mee-t this objection, two other types were made involving the same prinqipie. The first made use of the regular Tissot type die cashing which requires but one opeaing through the facepiece. The iahaled air enters through the casting, and is ieji into the extejrnal chamber through an -69- LATEST TYPE MILLER TIS30T MASK WITH GESR CARRIER. •3294 lUTEBIOR VIEW OF MILLER TYPjil TIS30T ikiASK SHOvvIUG 3P01GE RUBBER BAhii AMD VEJSTILATIWG TUBSS. opening in the inner wail, arid is distributed between the eye-pieces in the same manner as the mask described above. The general comfort and efficiency of this mask was improved by altering the size and shape of the curing form to eliminat all unnecessary dead air space. A second mask of the same general type was designed in which the inhalation tube, clarifying tube and eye frames are molded in one piece. The inlet tube comes in from the left side under the eyepiece and curves up between the eyes. The air passes out through a simple brass Stamping which permits the flutter valve and guard to be inclined at a very large angle from the chest. The lower portion of the mask is designed so as to fit the contour of the chin eliminating the necessity of a chin rest. The mask is fitted with a non -dimming arrangement con- sisting of a soft sportge rubber dam which fits over the nose and cheeks, separating the eye chamber from the lower or respiratory portion of the mask. The dam is pierced by two curved rubber tubes which deliver the air directly under the nostrils. The inhaled air then enters the mask between the eyepieces and is distributed against the lenses by a baffle. It is then passed down through the "ventiliating" tubes to the nose. On exhalation the check valve in the canister closes preveritiilg the moist air from returning through the "ventilating"' tubes and' thereby dimming the eyepieces. The venti^atla'g tabes' co-ntaia enough -dry air'-f?om the inhalation to take care of the.' difference of -pressure between the two chambers at the Be=gincing of exhalation. Sample masks of this type have been given cc«aplete tests with- excellent results in regard to aomfort* resistance and diaaiing. Kraus Type . A mask of special design has been made by Dr. Eraus of Clark University at the Hood Rubber Go- It embodies the non-dimming principle of ven-tilating tubes and is equipped with a by-pass so that. .only a portion of the inhaled air is drawn over the eye-pieces. The oval eyepiece frames are molded as a itnit and fit tightly to the eyes like g:oggles. A flap fits arotmd. the nose pr even tiJag exhaled air from re- turning to the eye chambers. Tb© angle tube is molded rubber and contains three brass tubes for inhalation and one larger one for exhalation. The facepiece is built and cured on an aluminum form. Tests show that this tjTpe of mask gives an excellent range of vision, is comfortable, and does not dim at zero Fahrenheit, Development of .Snout Type GaBiater . Late in the summer of 1918 development work was undertaken to produce a mask of the general type of the German and French AR5 masks, with the idea that a mask of this type might be more effective as a piece of equipment for offense operations than one in v^ich the canister was carrieii in a separate haversack and attached to the facepiece by a connecting hose. It was found, however, -71- DR. XR&US' "mSIVERSITY MASK UKIVSRSITY MASK Side Viev.' UUIVERSIXy li&SK Interior view showing one-piece molded clarifying tubes and rubber flap over nose. that in order to larovide an adequate filter to remove the various toxic smokes which wer« being used in increasing amounts, i«>)Uld entail the addition of so muph weight and lareathing resistance in the canister that this worlc was given up after a few experimental models had been made. Canils.ters for Army Masks. Standard Box Bespirator Canister. When this experiment was started^ about the first of August* 1917, the army canister was in production as a S-3/8" x 4-5/8" oval, corrugated can, 7" hi^, with valve seat in the canister bottom and nozzle soldered to the top. Inside ..a fine wire dome screen about l-l/2" high covered the full are of the bottom, and above thi£ were packed three layers of charcoal - soda lime mixture, the layers being separated by cotton wadding pads. Above the mixture was a layer. of turkish toweling upon which was a stiff, flat screen, and 1he whole held down by two rectangular springt each having two wrongs which were forced under inwardly pro- jecting ears at the top of the canister. This canister was* in practically all details, a copy of the British canister, and was giving general satisfaction for war gag protection. Study of Standard Qanister, For months^ the canister work of the iviechanical Kesearch deotion, under the bureau of Mines, -72- consisted of a detailed study of the existing canister and its coioTDonent parts in relation to air flow resistance, chemical life» moisture effects, mechanical durability, etc* From these studies we have reports as follows: KSSiSTAJSGiS OP CAiUiiTEii iaXXmitfiS: Factors affecting resistance of mixtures. Variations due consolidation, iiffect of size of granules, iiffect of depth of mixture, jlffect of pressure, RESISTANCE OF GAKISTER FILTER PADS: Factors affecting resistance. iiffect of pressure. ilffect of thickness of pad. (Ho. of layers) Variation in area. Effect of previous history. Effect of weight of pad. Effect of humidity. Resistance of pads between layers of mixture RESISTANCE OF MISCELLANEOUS PARTS OF CANISTER: Resistance of base plug. Types of ruober check valves. Resistance of base plug and old type valve. Resistance of base plug and new type valve. Notes and conclusions on base plugs and v all's s. Resistance of packing screens. Resistance of top outlet orifice. Resistance of toweling. Jtesistance of convex screen and spider, CANISTER PACKING SPRING. LIFE TESTS ON CANISTER CHEMICALS. TESTS ON CHANNELING. EFFECT OF JOLTING. Study of modifications . In addition to the study of the existing canister, sane work was done on suggested modifioa- being tioDS, such as check valve guards to prevent the valves fron/ -73- blown off by explbsiona,, special hemispherical donie screens to improve chemical life, moisture detectors to be inserted inside canister to show if a cani&ter had been damaged by dampness, effect of various arrangements of baffles and cottoi pads 00 the resistance and life. Typ« Changes af S-tandard Canister. About January 1., 1918, the, standard canister was changed ;to Type G, which differs •from the older Type C principally in that it is only 5-l/2" high. Type H succeeded Type G about April 1, and differs from it only in the interior -packing.. About July 1,, Type J became standard, this still retaining the 5-1/2" height, bu:t decreasing the amount of packing mixture so as t o leave about I'-l/S" at the top empty* This unused space required a change of spring to tfe? Z type. The above changes in the standard canister were not made by this Station, but are here referred to as each change called for corresponding te-sts and invest! - g5^tiping and sealing require careful work in produc- tion and inspection., and even with the greattest skill and care, imperfections are almost impossible to avoid. This chance of defects together with the labor involved makes the process undesirable. iSucked-On Filter . In August a suggestion came from A-H. Little, inc.", to mold or form a fiber filter jacket on the outside of a fine screen frame by suction from a water pulp solution. They also suggested cotton-seed hull fiber as a very promising material for this form of filter » The first filters based on this idea were made by holding and rotating the screen frame by hand in a tub containing the solution, suction being applied by means of a hose leading from a pump. Barly in October, a simple machine was installed by means of which better control could be secured of such functions as rotation speed, depth of immersioii, concentration or solution, suction, pressure, etc. Vi/ith this machine the problem was studied until the last of iiovember, making filters in the form of a cup which could be slipped over the "1919" lA^ar gas con- tainer and sealed to it St the -upper edge. ..Attention was #^ r^ O 3329 "SUCZEB-OU" FILTER AiD 1919 CAWIST3R gJT W^fh-l ll .i rt ^ I i ff j^ — .St— r- "^ tea afl! ^' Siar" m o 3315 SXPERIi^iENTAL, AUTOMATIC kAOHlKE FOR "SUGiCSD-OK" FILTERS WAR DEPARTMENT CHEMICAL WARFARE SERVICE RE5EACH DIVISION MACHINE FOR FORMINQ SUCKED ON FILTERS IN LARSE SCALE PRODUCTION CAPT. El J>. LAMBERT 2 2323 given to such points as propei" mesh of wire for the frame, possibility of removing the frame after forming, effect of varioiis fibers BM. methods of treating them, concentration of solutioii-, suction pressure » rotation ^peed and depth of immersion, in addition to this a method of compression of the material after function was devised to secure greater density and compactness. 'The method and rate of drying of the filters play an important part in the final state of the material and required considerable study. Sucked'>pn Filter Machin es, iiarly in Kovember it was realized that we were making filters of luiiform good quality and "that the development could be hastened by constructing a machine with automatic features capable of producing filters on a large scale. The United Shoe Machinery Corporation understood the design and construction of a machine, but before much had been accomplished the signing of the armistice caused the order to be cancelled. At this time it still seemed desirable to construct an automatic machine, though of simpler and cheaper design and anall6r capacity, to complete the^ develop- ment work on the filter', and this was designed and dravm be- fore an order came to cease all experimental work by the end of the year. guture of Suck e d -On Fi lte r. The work on this sucked-on filter and apparatus for mating it was in a very satisfactory state of development when the end bf hostilities removed the mili- tary necessity foT smoke protection and made further work -87- useless-. Had the war Gontinaed* there is little doubt but that' this filter would have been used with the 1919 canister with satisfactory results from the standpoints of resistance^ weight, mechanical strength, cheapness, rapidity of construq- tion and protection. Qonolusion . The type of canister first used, which followed former British design, served throughout the war with only very minor changes in details of construction and pacj:ing, and it gave excellent protection.. The efforts to modify and improve that canister gave no result that warranted any radi- cal change, though those minor changes gave valuable improve- ment in the protection. The principal new work done was in developing smoke filters. After studying the many types suggested, a few^ including the 1919 felt wrapped canister, the same canister m-'ith sucked-on filter, the accordion filter, and the molded pulp, doughnut filter canister, were developed far enough so that had the need coatlaued,. any one of them , could have been praduced in quantities to meet army require- ments. The sucked-on filter canister seemed, ^oy far, the simplest, cheapest^ and most practical form. The Carbon Monoxide Army Canister. Work was started on this I ■ I ■ ... — " I * - " ' problem at the request of Pr. W.X. Lewis, who had been ad- vised of the need for army protection against carbon monoxide by members of the A.ii-F. and of the British Liaison oervioe. The device was intended specifically to be used in pill boxes -88- from which machine guns were fired and in sapping and mining operations. A suitable canister filling material to absorb GO had already been developed in ths form of Hopcalite, but it was practically impossible to get any details, or in fact any general information as to the probable requirements that a canister would have to fulfill. At first a concentration of one percent was assumed but later .1 percent was considered as the probable maximum. The length of time the canister would have to operate was also taken at a high figure aM later reduced when it was found that the absorbent materials were more effective than had been anticipated. The whole problem should only be attacked by assuming certain hypo- thetical conditions and attempting to design an apparatus to meet them. A can of approximately the size of the regujiar army canister was finally developed that was thought would give sufficient protection for any ordinary needs. Several attempts were made to secure adequate information by sending cablegrams to the CW.S. Director in France and also to mem- bers from the American University going overseas, but no in- formation of any sort was ever received. It was assumed, therefore, that either the problem was not of the importance imagined or that changing conditions had rendered the use of a carbon monoxide canister unnecessary to the army.. The work was carried on in cooperation with the Defense Chemical Research Section under Col. A.B. iamb, ani was completed with -89- the final revoTt of Mr. M.H. Reymond-. Quic k Deta chab l e Hose CoaneGtiQp . . During the work af this section on canisters, a number of instances developed where t the need of a quick detachable hose connect ioja appea^red der sirable. A great number of suggestions were Qonsidered to meet the conditions of absolute tightness, easy operation, and means of easily locking a connection in place, against accidental derangement. A careful study was also made of the patent literature, A form was finally developed utilizing a spring washer to clamp two flange faces together with a suitable gasket interposed between them. The flanges were attached either to pieces of the hose or to the canisters as was desired. Two overlapping cylinders or cylindrical cups containing slots through which extensions of the spring washer were extended were used for the clamping means. One of these cups was placed under one flange, directly while the other had the spring washer interposed; between it and the flange. After being looked in- posit ion » the gasket was therefore always under spring tension while a positive section of metal was utilized to prevent the flange parts from being pulled out of contact. The connection is fully described in the report by Mr. M.H. Reymond. C aqistef Dust Filter . The work on this problem was started following receipt of a cablegram from abroad stating that danger e-xis ted in dust from. canister materials being drawn -90- akACK Fabbic rtOP CRLITe WHCTLERX-n-. Cm.ciun CHioieiDS _ PLATE V-FlrdAL Of6l«l!l OP SIM&Ue Ur«iT-^CPlft-CANlWe«- THE NORKiS PETERS CO.. WASH.. D. C into the new Tissot type masks. It was feared this would affect the eyesight of the user or dim the goggles. Careful . experiments were begun to try out a large range of fabrics which would have the properties of low resistance and effect- iveness in stopping canister dust. Dust was produced experi- mentally by grinding up cnarcoal and soda lime and weighed amounts were utilized in a special ap"oaratus to obtain quanti- tative results. Several materials were found suitable, the best of these being cotton wadding compressed ii^layers of the proper thickness. The next best material was a form of true cotton felt anid this was more practical for use for many pur- poses than the cotton wadding since it could be used in sheet form. A sample of cotton table felt also showed desirable properties. A number of wool felts gave excellent results, but were deemed too expensive to employ. Final tests were made on the materials properly placed in canisters by men with Tissot masks under heavy exertion on an ergometer. J)Jo dust sufficient to affect a man was drawn in, using the best samples The work is completely covered by final renort of Lieut. P. 3.. Sprague, Pvt. R.S. Mariot and Pvt. U. Prozan. Summary of work on Paper Develapment . iiarly in: the year 1918, the use of toxic smokes in warfare necessitated the develop- ment of a filter which would successfully remove suspended particles without offering a high resistance to the passage of air. Paper offered one of the most promising materials -91- for this purpose, and several, lines of investigation v/ere independently started at government laboratories and private mills. In July 191B^ this wQiXls: was coordinated under the direotion of Dr, Wm. jSovard,. Viiork was first concentrated in developing a paper for u.&e in the accordion filter Simultan- eously with the development of this filter mechanically, and the efforts of the laboratories were systematized so that work would not be duplicated, - work on paper using wood pulp was c onfined to the Forest Products liaboratories, investiga- tion with rags and cotton linters was done at the bureau of St&ndards, and puffed paper and sheets containing celite and diatomaceous fillers were developed at the Clapp Laboratory.- The commercial field was canvassed for a suitable paper, but with the conclusion that the most promising industrial papers, namelyi blotting, filter, and unsaturated felt papers, were all too hard and compact. Considerable experimental work showed the superiority of a thick, single-ply paper. Mr. Ellerson of thiQ Albemarle paper ilfg. Company, offered the use of his mill for an ex- perimental run, and a thick rag sheet was produced that was tested extensively in the accordion filter and gave very good protection agaiiast smoke. A portable pressure drop apttara-tus was developed to facilitate mill testing of the paper, and trials proved that this paper was reproducible and that the manufacture could be easily controlled. This paper was also -98- efficient wiaeii used in the flat plate filter. In October 1918, the development of the Logan or 1919 canister entirely changed the paper situation. The most ad- vantageous method of using paper with this canlsfer consists of wrapping the material around the canister. The thick paper use-d in thie accordion filter" was not suitable for this form,, and so new papers were devel^oped for the purpose of wrapping the canister with from 4 to 20 pliJes of th@ paper. Photomicrographs of many fibers were made at the Bureau of Chemistry.,. Department of Agricalture, and these, together with a study of the paper making' qualities of fibers, indi- cated the superiority of raw cotton, cotton linters, wool fibers, and celit« as raw materials. Haw rags and linters were developed at the Bureau of Standards; relations were ob- tained showing the variation of density, resistance, and other properties wiith composition and machine conditions; and a paper was developed that when wrapped ten times around the canister gave a fairly low resistance and good protection.^ Wool,, by reason of the serrations and physical properties characteristic of animal fibers, seemed particularly suitable for use in smoke filter paper, and in work done at the Forest Products Laboratory,, efforts were made to utilize the short wool fibers that are not used in making blankets,, clothing, or other essential war materials, fixtures of wool,, rag, and specially treated wood pulps were used; variations of physical -93- properties with change of coniposition and conditions of manufacture were studied; and a paper was developed that when wrapped six'times around the canister gave good pro- tection with a low resistance to the passage of air. At the Clapp Laboratories, mixtures of wool, rag, patented puffed paper, and celite were developed, but this type of paper never reached the same degree of perfection. The mechanical strength of the wool paper was improved by forming the sheet on netting, smd as this did not impair the efficiency in any way, the resulting paper was very well adapted tOi wrapping the 1919 canister- This paper was devel- oped at the termination of the work, and was not exhaustively tested, bat showed great promise for use in wrapping the canister for protection against toxic smokes, and with an area of 75 sq. in. have good efficiency with very small re- sistance. Protective Clothing . With the advent of mustard gas the need arose for clothing to protect the wearer against its action not only under field conditions, but in factories and shell loading plants where the gas was manufactured and loaded in the shell. Inasmuch as this gas not only attacks the exposed portion of the skin but very rapidly permeates ordinary cloth- ing, it became necessary to provide a complete head to foot outfit which, in combination with the mask would entirely shut off any access to Ihe sfcLn of an atmosphere containing mustard -94- gas. The problem was still further complicated by the fact that the majority of materials which are impermeable to mustard gas also prevent the transpiration of air, thus hold- ing in the heat and moisture given off by the body and almost completely stopping the necessary access of fresh air to the pores of the skin. The first material which was found avail- able for this purpose was the linseed oil impregnated sheet- ings which were developed almost simultaneously by workers in this country, in France, and in England* Two suit designis were developed .one for field use, following the general lines of the union overall, but designed with a view to tighter closure at the wrist and ankles and opening in the front. A cowl was attached to this suit which overlapped the edge of the mask, thus clothing the entire body with the exception of the hands and feet. Sample.s of this suit were made up and submitted to the Gas Defense Division. A second type of suit was developed for factory use, made in the main of the same material, but differing from it principally in the provision of a special helmet in place of the mask and a means of ven- tilation by compressed air. So far as we know, this suit was never put into use, duer in- part to the restricted range of action of a man attached by a hose to an air line and , also on account of the difficulty of securing a supply of compresseti air at a pressure which could safely be introduced within a suit of this nature. -94-a 1137 AIR LIWSD HBLiviET AND SUIT Front View Showing suit inflated. Owing to the unsatisfactory situation in the matter, of suits for- factory use, research work was conducted by a group of chemical- engineers working under the direction of Lieut, Abraham to nrpduce a material which would allow a reasonable skin ventilation, and still protect ths skin again s' the action of mustard gas. A fabric was finally produced- consisting of a. sheeting coated with a mixture of glue and gelatine which .allowed the transpiration of moisture nearly as rapidly as the uncoated fabric and yet offered a high de- gree of protection against the passage of air containing mus-r tard gas. It should be pointed out that while this fabric did not allow the transpiration of air, it was demonstrated that a large amount of the. discomfort arising from wearing the linseed oil coated suit was due to the fact that it pre- vented the evaporation of moisture given off by the pores. This fabric was not suitahle for field use, however, on ac- count of the fact that under th^e action of water In liquid form, such as rain, the coating stiffened, ^and after .prolonged service it cracked. This fabric was, however, finally recom- mended to the Protective Clothing Committee as the one best suited f6*- factory use. Late in the summer of 1918, a request was received from the A.S.F. to put into nroduction at once suits and gloves for field use along, the lines of- samples of suits and gloves sent by a courier. This suit was made of linseed oil fabric -95- li^PSRVIOUS OVERALL SUIT FOR PROTECTION AGAIKST HS . iJ'ront View. OOATED GLOVES FOR PROTSGTIOiJ AGAINST LiUSTARD GAS and at the request of the Gas Defense Division this group at once undertook the nianufacturing development of this order. A linseed oil fabric was developed having nearly twice the time protection against mustard gas afforded by the French suit, while in place of the same material for gloves there was substituted a pyroxalin coated fabric produced under the direction of Lieut. Abraham. This method of forming the glove was superior to the French, - first because the glove could be sewed up from tjie original fabric much more readily than from impregnated fabric and, second, because the coating after sewing effectively filled all needle holes and seams, and thirds the pyroxalin coating was much superior to linseed oil in initial protection and in service period. At the time of the signing of the armistice, the work of coating the fabric for the suits and meoaufacturing and impregnating the gloves was in charge of various members of this division working under the direction of Lieut. Abraham. Sufficient fabric had not yet been accumulated to put the suits into large scale production. Mavy Facepieces and Canisters . Inasmuch as practically all the various types of navy masks upon which work was undertaken had the canister more or less integral with the faoepiece, the canister and faoepiece will be reported as a unit. The work at this Station on gas masks for the navy was initiated in Uov^mber 1917, as a continuation of the work which Lieut. Commander A.H.- Marks had begun toward developing -96- EARiY TYPii OF NAVY MASK Contains nose clips and Qiouthpiece »1 a Snout type mask, The details In the construction of this mask were care- fully worked out and specifications prepared for the navy. Production was started immediately and a large nximber of thesf masks manufactured. In its final form the mask embodied principles taken from each of the three best masks in use at that time; :3nglish, French, and German. In external ap-oearance, weight, and arrangement of head harness, the mask resembled the earlie German masks which wer« constructed of rubberized fabric. The flutter valve, mouthpiece, and noseelip are of ^erican pat- tern, similar to ±16 Snglish design. The canister and check valve are similar to the French A.R.S. Shoulder Carrier Mask . About the same time that the Snout type mask was put into production, the Mechanical Section began the development of a mask for naval officers. The face- piece of this mask was almost identical to that developed about the same time for the army Tissot mask, the distinctive feat;are being a die easting with the inlet tube at right angles to the flutter valve, allowitig the flexible tube to be carried back over the shoulder to the canister which was suspended by a rope harness on the back. The facepiece is composed of pure rubber protected by an additional layer of tough black stock to prevent cuts or punctures. 1?he eyepiece fitames are moulded from the same black rubber. The mask is -97- cured oo an aluminum form without wrapping. In assembling the mask, the eyepiece lenses are held in place by frames with lugs which are bent up under a washer so as to press the rubber tightly against the glass. The inhaled air is distributed to the lenses by Y-shapec rubber clarifying tubes. The chin rest is made of rather soft rubber with horns which fit on either side of the chin to hold the mask in place. The head harness is made of two rubber bands about one inch wide passing around the head connected to the top of the mask by a non-extensible rubberized fabric strap . About one hundred of these masks were made and submitted tb 'the *a'vy for test, but this type was never officially adcpted>. Head Canister M ask. Baring February and karch 1918, a mask was developed by the Mechanical Section to carry the canister in back of the head. The facepiece of this mask is of the general Tissot type» but embodies several novel features. The inhalation tube extends around the left side of the head and is attached to the facepiece over the eye.- It terminates in a flat "dif- fusing tube'* of semi-circular profile which extents down be- tween the eyepieces covering an oblong opening through the facepiece. The incoming air is distributed to both lenses by means of a baffle made of a thin strip of rub^ber. The -98- HEAD CANISTER AIJD MA3K exhalation tube consists of a brass tube bent sharply upward so that the flutter valve is inverted and stands parallel to the center of the facepiece, the upper end just belo^r the center of the eyepieces. The head harness is attached to a and hood of open mesh fabric which fits over the head/supports the canister in a horizontal position at the back of the head and neck. This mask was submitted, together with the shoulder carrier, type described above, to the navy, but rejected in favor of a mask designed by Lieut. Squiers of the navy and Mr. Coe of the U.S* Rubber Company which carried the canister directly on top of the head. Helmet Canister -Mask . In June 1918, we were requested by Lieut-, Squiers to cooperate in improving the head ty^e mask with special reference to facepiece design and tha development of a smoke filter. The facepiece of this mask is constructed of red, non- blooming rubber, covered with olive drab stockine-tte. A hood of the same material covers the head and is reinforced by a single elastic tape extended around the head through loops in back of tha hood. A felt lined aluminum helmet, on which the canister rests, is attached to the hood by three elastic tapes. To the forward end of the canister is attached a Y-shapec aluminum casting. A rubber inhalation tube is attached to eaci -99- aaflA- EABLY TYPii OP UAVY HEAD MASK WITH FELT FILTER AND WATERPHOOP COVER. A COMPLETE lUVY EMIi i^lASK ^klTHOUT SmKS FIITSB. of these outlets and oondusts the inhaled air into the eye- piece wall. The exhalation tube, upon which the flutter valve is seated, is formed from rubber as part of the facepiece and extends upward between the eyepieces, a rubber dam separates the eyepiece chaiuber from the lower part of the mask. Moist air is prevented from getting up to the eyepieces by small flutter valves seated on metal frames in the dam. The face- piece and hood are cured on a flat form cast of aluminum. The eyepiece forms and the rods extending upward from them to serve as cores for the inhalation tubes are part of the form. The work of this Station on this facepiece has been an attempt to increase the comfort and efficiency of the mask. The comfort of the mask has been increased by bringing the inhalation tubes in at the side of the eyepieces instead of the top, thus relieving the pressure on the eyebrows. The dam m. th which the mask was equipped gave a, great deal of pressure oh the bridge of the nose while th© anall flutter valves raised the resistance to inhalation greatly. A more comfortable dam known as the Miller type was substi- tuted and the snail shaped ventilating tubes which have proved successful in .preventing dimriiing in the army masks were sub- stituted for •, the valves.. In order to make these tubes effect- ive, it was necessary to develop s. small mica disc check valv^ -IQO- to fit in the intake end of the canister. The binocular vision has been improved by decreasing tli distance between the eyepieces. This was accomplished by making the facepiece form. and. the core of the exhalation tube as thin as possible between the eyes, and moving the eyepiece forms up to the edge of the form. A detachable flat felt ■filter outfit for this equipment was also developed by this section. This consists of two of the rectangular felt filter pads enclosed in their v;aterproof jackets, containing a total of about 60 sq, in. area, which was attached by straps to either side of the helmet, the air connection being through a quick detachable Y at the^ back of the canister. Mavy Submarine Canis ter. Another minor developqaent carried on fox tfee navy was the development of an emergency canister which could be used with various types of packing. This is a canister similar in general appearance to the canister on the German mask, equipped with a special mouthpiece and nose- clip,. but without a facepiece. It. is contained in a box ap- proximately 5g-" in diameter and 3" high, and for use over shor.t periods is a very satisfactory emergency outfit. MISCELLAMiSOUS DEPEWSE PROBLEMS. Horse Masks . The original work on the horse mask was started late in 1917, and consisted in the main of the development an' manufacturing methods for a mask modeled along the lines of the British horse mask brought to this country by Gapt.Dudleyr -101- MVy SUBlviASIUiS OAHISTER NAVY SUBLiARIM^ CANISTER. Tills iLast was put into orodaction by the Gas Defense Divisioi. late in the spring of 1918. Certain defects, mainly in the matter of breathing resist&noe which developed in field testp of this mask, together with a new type of fabric im-pregnation worked out by tbe Chemical Development Section, led to a re- opening of this problem early in the sumuer. As a result of the cooperation between the Chemical Development c:'ection, the Development Section of the Gas Defense Division, and the members of this section, a new type of horse mask was de- signed and production details viorked out. This mask was a very radical imiorovement over the early American and British masks in that its breathing resistance was reduced to pract- ically nothing. A new type of harness was also worked out which allowed the mask to be put on and off entirely inde- pendent of any bridle or halter which the horse might be wearing. At the time of the signing of the armistice, the horse mask factory of the Gas Defense Division had the ma- terial on hand and the plans worked out for an extremely large oroduction of masks of this type. Protection of Horses' Fee t. Sarly in the spring of 1918, request came from the chemical laboratory of the A.3.F. for the protection of horses' hoofs and ankles against mustard gas. A very satisfactory solution of this problem was worked out, consisting first of a steel and faoric pad for applica- tion between the shoe and the hoof and, second, a boot or gaiter covering the entire lower limh from the knee to the -102- li^IPERVIOUS BOOTS AND PADS TO PROTECT HORSilS' LEGS AND HOOFS AGAINST HS. shoe which is made of a heavy grade of duck coated on both sides with pyroxalin. The only exposed portion of the leg below the inee was the slight cavity at the back of the foot between the pad and the frog which was filled with an ab- sorbent packing of tar and oakum which was to be removed ittmaxiiately after a horse came out from an area where mustard gas was present, iicknowledgement should be made in connection with this wo^rk of the substantial assistance rendered by kr. William J. Kent of the United St«tes Hubber Company, who dur- ,ing the course of this development extending over a period of several months devoted the majority of his time to work along this line. This work was reported by Dr. W»K* Lewis to the ^--JJ'J?*. but as the end of the war came shortly after this, nothing was done further on this problem. Trench Fans and Sprayers . During the winter of 1917-18, de- signs for both trench fans and trench sprayers for removing the gas from trenches were worked out by this Division along lines and models submitted by Major Auid and Captain Dudley of til British Anti-Gas Serviee. These were put into experi- meptal production and specifications on them turned over to the Qas Defense Division. Adaption of Telephone to Gas Mask . A large amount of work was carried on in this section in testing out and refining the relative merits of a large number of devices which had been worked out in connection with tTie adaption of the telephone to the gas mask. Jn_ this investigation,' vrery valuable coopera- tion from the Western Blectrie Company,* the Stromberg Carlson -103- - Company, and the Holtzer Cabot iillectriG Compan-y, ffianufacturei af telephone equipment. Telephone transmitters were tried out at all points of the mask from the facepiece to the top of the canister* Our final recommendation in this connectioii was that the transmitter be attached to a "T" located in the flexible hose about 3 inches above the top of the canister. Aviators' Maeks. iiarly in 1918, a member of this staff was detailed to work with Dr. jfiyster of the University of Wiscon- sin, who was acting as consultant with the Aviation Board in connection with the development of a mask, for feeding oxygen to aviators at high altitudes. This work was relatively un- satisfactory on account of the constant change in specifica- tions to be met. In the summer of 1918, however, when this work was taken over by the Aircraft Production, our work in this connection was a^ain renewed at ths request of Capt. HultrS, and a man detailed to work exclusively on this problem. As a result of this work, several very satisfactory models were developed and the work is being carried on at the present time by the Aircraft Production Board v/ho have taken over all of the models and special tools which were developed in this connection. OFFENSE PROBLEMS MobllLe, Taxlc- GflS- Cylind er.- Work on this problem was first started by the jBoimer. Mechanical Section under Mr. H.H. Clark on request of Mr-... G.JU liurrell for a mobile urrlt. that would -104- AVIATORS' (r:YGEE msK Type V. G-oggle type, eyepieces exteiided. AVIATORS' OZYGSN MASK Type VI. replace tha emplacement cylinders that had been previously used for toxic ?as cloud attacks. These latter were ditfi- cult to put in position without protection^ and since a long time was taken to properly place them, their use was -'■ery uncertain, ..since favorable weather conditions had to oe waite- for in addition to the tins taiken to' place them in positiowo i-uaother defect of the. eui-olacement apparatus was the nozzle which gave an excessive amount of noise, and gave warning of ■ttae attack. The work of this section comprised the develop- ment of a suitable cylinder for the gas, atop valve to close the cylinder during charging and after discharge, and to pro- tect the opening val'/e, and the opening valve itself that was used when the tank was fired. A suitable nozzle was also developed to decrease the noise of discharge. Recommendation of this section was for a light tanls. about 8" in diameter, 16" long, and this was adopted and specifications drawn up by the Ordnance Department. The work done on the stop valve was in the form of cooperation with members of a valve com- mittee from the Pyrotachnic Section and the Ordnance Depart- ment.. A satisfactory valve, of the semi-needle type with forged bronze body and .Monel metal stem was finally produced. This valve was put in .Tjroduction by the Ordnance Department. A special type of si;op valve with a hollow stem was developed by this department and recoim; endcxtions were secured for furthe. development from the Ordnance Departinent . A number of opening -105- TYPE MO. 2 FABRIC S^OZZLjH - UQ'iQEZD NUB. CA3T IROW OP^UWG VALVE - FUSE DIRING DWIO^. valves were developed, the final one being in the form of the Crown Cork and beai Company bottle cap, using a lead gasket backed up by cork. This seemed to promise favorably at first, but later developed defects that caused its rejec- tion. The wprk on the discharge nozzle resulted in the r»ro- duction of one using a diaphragm of snecial cotton fabric which gave good atomization of the TJhosgene -chlorine mixture used Xn the toxic gas cylinders and a high rate of discharge with small size and, weight, its single defect was the possi- bility of cQx^rosion by the toxic gases. Impregnation experi- ments were started to overcome this objection, but were not completed at the time of cessation of work at the University. Experimental tes-ts showed the nozzle to be satisfactory re- garding corrosion during discharge, so it would only' be nec- essary to pr-otect it during storage and transit. When the work of the Mechanical Section was taken over by tbe Mechanical Research and Development Section, a number of the above problems remained unoomuleted, and a vigorous attempt was made to eliminate them or to develop them to a successful conclusion. The bottle cap opening valve did not survive a rather severe sexies of tests made by the Pyrotechni Section, tests that,, however, the valve put into production would without doubt also have failed under. It was not pos- sihl^. in the time that elapsed before experimental work at the University was closed to develop the fabric nozzle com- pletely,, but an entirely new type of openings valve was -106- TYPi5 NO. 2 FABRIC WOZZLji - NOTOII^D NUB, CAST IHOIi OPENING YALYS - SLKCTRIG PiaiNfi SQUIB. successfully developed. This was in the form of a nub of cast iron forming part of the valve casing. This was grooved and had two arms pro, j-ec ting from it so that the nub could be burst apart by the action of a small t)0inted tjlunger impelled by a light powder charge. The powder charge could either be ignited by a blasting sguibb or by a time fuse. This typd of valve operates instantaneously as compared to those utilizing a melting out compound that is variable in its results, Wo noise is made but a slight metallic clicli when the nub is ruptured. ■ It is also absolutely tight and there is no chance for leakage to develop. Since the grooves cut in the nub expose the metal,, this can be carefully examined and tested for leakage. If there are any defects, they will show at once and, if not, it can be assumed that the valve will re- main absolutely tight. Tests of this valve were made, at Lakehurst, N.J., and at the University. They appeared very satisfactory and encouraging to the Trench Warfare Section of the Ordnance Department, -having the toxic gas cylinder in hand and this Division requested that full details and specifica- tions be provided them so the valve could be further developed. Flaming Bayonet . This problem originally came to the former Mechanical Section. of the University from the Pyrotechnic Section, and was taken over -by this, section together with other work during^ a period of re-organization. The original suggestion of the device had apparently come from Lieut. Ball. -107- fiXPLOSIVS; VALVE FOR MOBILi; GAS ATTACK CYLINDER and Lieut* Patch of the Trench vi/arfare Diyision of the *^rdnanca Department* The idea was to aon struct a small flame T>rooector thiat could be carried on the end of a rifle and which oattld he used during hand to hand bayonet fighting. The first type ooinprised a cylinder carrying a piston to force out the fiLaming liquid, and this was actuated by a spring or by air pressure , A form of pilot light that would be invisible to the enemy was to be provided for igniting the flaming mixture* ^he work of the Mechanical Section was firs to develop a suitable non-luminous pilot flame, and this was finally secured in a fairly practical form through cooperatior. with the Justrite Company of Chicago, who adapted one/ their flame -proof min-er''s lamps for the purpose.- The flaming liq- uid used was gasoline or benzene. The problem was in this condition when it was taken over by the Mechanical Research and Development Section. At this time the whole problem was gone over carefully to see that it was being attacked in the right angle. A conference with Major Matthews and Lieut. Ball of the Trench Warfare Division, Ordnance Department developed that it- was not essential that a flaming liquid in the ordinary sense should be used. A large flame- of gas or liquid preferably, from 5 to 10 feet long and 3 feet in diam- eter would be desirable. Simplification and reduction in weight were very essential factors. The final device complie- ted by the Justrite Company was successfully demonstrated -108- o o d3 o t— ! pq s o Pi o M Eh a .3392 before mempers of the Ordnane-e Department and the Pyrotechnic Section. There was also present IVEajor H.W. Holland-, who had had considerahle experience abroad training with the jSnglish troopg in Flanders^ He stated that the weight of a device on the end of the gxm would offer no practical abjection or interference with the use of the bayonet if it could be made to function successfully. He favored the proposal to use separate shots or cartridges rather than a single flash whose duration could be controlled by the operator. Results of this demonstration were eiicouraging and work was continued actively to attempt the use of compressed liquid gas both as a pilot flame and a means to project the flaming liquid. Mixtures of compressed gas and flaming liquid were also con- sidered. A large amount of carefully taken data and experi- mental work showed that the production of a satisfactory pilot flame was very difficult, and a much simpler method would ' be to employ the flash from a cartridge or flare mixture to ignite the flaming liquid. Several forms of apparatus were worked out experimentally, but the closing dpwn of work at the University allowed only one of these to be put in fairly complete form. This last apparatus com- prised a small rectangular shaped can that could be fastened to the rifle by an easily detached clip just under the end of the barrel. This can contains six cartridges containing a mixture of kerosene and a liquid gas mostly propane. The -109- H a ph O >H !x en a M M p^ " s EH fi rH M fc; o Eh Eh ri\ i'ii ;.'.•':•■ 1 W:cJ:':vv:"-i;.;*.v.'r ■■.■ s :/■';■'■'•-'■«•"- ''.'.yj: . '>.«'*tjt<.v-.V::'.'-^,': / mwZ U « X o i ^ ^ Qontainer of pressed steel, but this apr»eared too strong to be rurttT^red with certainty. A recommendation was made, there- fore, that glass or stoneware containers be experimented with before deciding as had been done that they could not be made satisfactory. This recommendation was followed and concluded the work of this section. Delayed Time Puse « This problem was one to test out a device for the Pyrotechnic Section that had been developed by the kechanical Sectioh, \Vhd did- not have proper testing facilitiet It was found too irregular in action to be satisfactory and this section was asked to propose a design on different prin- ciples. The work was about to be started at the time experi- mental development was shut down at the University. PYRQTECHHIC SIQE.AL PROfiLSMS . 4" Kavy |