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to use technically trained men temporarily for positions of an executivezcharacter, instead of for experimental work, which duties-were always performed with a splendid spirit of devotion to the welfare of the Field as a whole. The sections on physiology andIpathology include names of international reputation. ORGANIZATION
COMMANDANT: Lt. Col. J. H. Hildebrand A.
ADJUTANT: Capt. G . P. Blakney
E. F. GAS DBRENSESCHOOL: Capt. W. A. Bush, R. E. Capt. H. Anderson, R. E Capt. I. J Bowman 1 s t 1,t. H J. Nichols
OFPGNSECOURSE: Capt. F . H. Scheetz 1st Lt. J. 0. Thoen 1st Lt. F. L. Firebaugh FIEI,D COMPANY: Capt. E. Patterson 2d Lt. D . L. Hough Mess and Billets: 2d 1.t. G. J. Levy Range and Town Major: 1st Lt. E. B. Peck POST SURGEON: Capt. R . I. Dorge, M. C.
SUPPLIES : 1st Lt. L. G. Eisele 1st Lt. B. G. Davidson EXPERIMENTAL WORK: Maj. E M. Dunn
Regorts: Capt. T. D . Stewart Artillery: Capt. F. H. Scheetz 1st Lt. J. 0. Thoen Chemistry: Capt. J. L. Crenshaw Capt. H . I. Cole Engineering: Capt. J. L. Alden 1st Lt. R G. Bowman Field Gas Experiments: Capt. B. B. Freud Ordnance Laboratories: (Shell opening, shell filling. gaine filling) 1st Lt. Edwin Smith, jr. Pathology: Maj. H. C. Clark, M. C. Maj. A. M. Pappenheimer, M. C. Maj. C . B. Farr, M. C. Capt. B. M. Vance, M. C. Physiology: Maj. A. N. Richards Cap. S. Goldschmidt Capt. D W. Wilson
The enlisted personnel required for all purposes numbered 250, and included a number of technically trained men assigned to the various sections. There were fifty-five major buildings, all constructed since April 1918,including barracks, mess halls, lecture auditorium, garage, machine shop, laboratories of chemistry, pathology, and physiology, animal shelter, stables, Y . M. C. A., warehouse, magazine huts, shell opening and filling plants, and gaine filling plant. The field equipment included a plentiful supply of mortars, projectors, cylinders, 75 mm. and 155 mm. guns and ammunition.
There were two projector ranges and an artillery range provided with protected observation post, telephone line, and trenches In conclusion, it is desired to add a word of appreciation of the attitude towards experimental work of the Chief of the
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Chemical Warfare Service, A. E. F., Brig. Gen. Amos A. Fries. General Fries is an experienced army engineer and acquired a remarkable grasp of the scientific problems connected with gas warfare. He showed himself very appreciative of the value of experimental work and exceedingly open to new ideas growing therefrom. He deserves a high place in the esteem of American chemists. DEPARTMENT OP CHEMISTRY OF CALIFORNIA UNIVERSITY BERKELEY
CONTINUOUS VACUUM STILL FOR “MUSTARD GAS”
I
B y ELPORD D. STREETER Received January 24, 1919
The apparatus herein described was constructed for t h e continuous distillation of “mustard gas,” or dichloroethylsulfide, (CH2C1CH2)2S. As shown in t h e drawing, t h e apparatus is fitted up for a study of t h e process and t h e products obtained, rather t h a n for plant operation. The work on this problem was left unfinished, because a change in t h e methods of manufacturing t h e crude mustard gas rendered this sort of a distillation unnecessary. This report is now being made as a matter of history, and with t h e hope t h a t some features of this work may be of value in solving some peace-time problem. T h e crude mustard gas with which we had t o deal, contained, beside a large amount of sulfur and organic polysulfides t h a t formed a tarry residue after distillation, considerable free hydrochloric acid, ether, a n d other low volatile substances t h a t have not been identified. Mustard gas itself boils a t 217’ C. at atmospheric pressure, b u t with considerable decomposition. I t may be distilled, under a high vacuum, but it is important t o limit t h e time of exposure of a given portion of t h e liquid t o t h e necessary high temperature, t o t h e shortest possible time. The construction a n d operation of t h e apparatus will be understood b y reference t o t h e drawing. The stock bottle for t h e crude mustard gas stood on a platform scale, t o facilitate determining the rate of consumption. The rate of flow was regulated b y a cock, and observed through a sight glass. The liquid then entered a pre-heating coil consisting of 50 ft. of I/z-in. lead pipe, in a bath of hot oil. This oil was kept at a predetermined temperature by means of valves in t h e oil circulating system (not shown). The hydrochloric acid and other low volatile substances vaporize in t h e coil, and in t h e earlier experiments made it impossible t o secure a uniform flow. Therefore a gas separator was installed. This consisted of a cylinder 4 in. in diameter and 1 2 in. deep, surrounded by a jacket filled with hot oil. The liquid entered a t t h e side, 3 in. above t h e bottom, and was withdrawn a t t h e bottom. A gauge glass was provided t o show t h e level of the liquid in t h e chamber. This level should be kept constant. The gas separated in t h e upper p a r t of t h e chamber and was led off into t h e scrubbing and condensing system t o be described later. A regular flow of liquid through t h e pre-heater was maintained b y controlling t h e valve on 1 Published by permission of the Director of the Chemical Warfare Service.
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Apr.7 = 9 = 9
GAS SEPARATOR 4'DIA. X 12"DEEP
/
OIL
OUTLET
HOT OIL INLET 2-
VAPORlZlNG TU
I
TO
wcuum
=
CONDENSER
t
I Fiu=F=/ / I rl DISTILL ATE
I
-GAUGE
3---c
RESIDUE SEPARATtNG CHAtIBER
01L
OIL
3-
GLASS
FIG.I-CONTINUOUS STILLFOR MUSTARDGAS
the vacuum line beyond t h e scrubbing system so t h a t the manometer on t h e gas separator registered I O cm. of mercury vacuum. This might be made automatic. The liquid was aspirated from t h e separator by t h e
vacuum in t h e still, flowing through a sight glass and two valves: t h e first a gate valve t o control starting and stopping, a n d t h e second a needle valve t o regulate t h e flow. It entered t h e vaporizing tube through a 3/s-in. lead
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pipe bent t o give a horizontal tangential discharge against t h e wall of t h e tube. This tube was a 3-in. iron pipe, g1/2 f t . long, surrounded by a jacket through which hot oil was circulated. The liquid flowed as a t h i n film down the walls of this tube, and the vapors formed, together with t h e unevaporated residue, entered t h e large separating chamber below. This residue was continuously drawn off into the residue receiver while the vapor passed on t o the condenser and was collected as a liquid in t h e distillate receiver. Both receivers were provided with 'sight glasses t o observe t h e flow and gauge glasses t o show t h e volume. The' operation of this apparatus proceeded very satisfactorily and though all runs were short, it could easily be made continuous by installing duplicate receivers and reservoirs for stock. Several runs were made t o determine t h e most satisfactory conditions of temperature and rate of feed. T h e best run gave results as follows: Average temperatures: Bath of pre-heater and gas separator.. Bath around vaporizing tube. . . . . . . . . . . . . . . . . . . . Bath around residue separator. . . . . . . . . . . . . . . . . . . Mustard gas entering vaporizing tube. ............ Mustard gas vapor entering condenser. Average vacuum (absolute pressure), mm. mercury.. ... Average rate of feed, Jbs. per m i n . . . . . . . . . . . . . . . . . . . . Average rate of condensation, Ibs. per min.. Per cent of charge as distillate.. ..................... Purity of distillate (per cent mustard gas). Per cent of charge as residue.. ....................... Purity of charne (per cent mustard gas). Per cent of original mustard gas remaining in residue (by difference). ..................................
............
........... ...........
............ ..............
150" C. 183' C. 150' C. 147O C. 136' C. 60 0.95 0.51 53.5 92.5 40.6 81.5
32.0
Other runs were made under different conditions, with t h e following conclusions: ' I-Increasing the temperature at any point increased the decomposition, lowering the vacuum and lowering the yield. 2-Lowering the temperature a t any point reduced the yield. 3-Increasing the rate of feed did not increase the rate of distillation, and reduced the per cent yield. 4-Reducing the rate of feed increased the per cent yield, but not proportionately, and reduced the rate of distillation. I t was attempted t o reduce the rate of feed sufficiently t o .obtain a quantitative yield, b u t this failed; though the residue could be further concentrated by a second passage through the apparatus. It seems, therefore, t h a t t h e time required for complete evaporation of the mustard gas from t h e film of liquid is longer t h a n t h e time required for t h e t a r t o flow down t h e tube of given length. Accordingly, if the work had been continued on these lines, a tube of twice t h e length would have been built. As stated above, there was found t o be a considerable amount of material vaporized in the pre-heater a n d separated in the gas separator. This passed through a n air condenser, t h e condensate being collected in a receiver and t h e gas continuing through two wash bottles containing 1 2 per cent sodium hydroxide solution, which absorbed t h e hydrochloric acid. The gas then entered a condenser packed with crushed ice, and t h e condensate was collected in a receiver surrounded with ice. The residual gas, which was insignificant after the system was cleared of air, was bubbled through water t o indicate t h e amount. A
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typical run gave results, expressed in per cent of original crude mustard gas, as follows: Condensate, air condenser., , , , 1 . 8 Absorbed in alkali., . . . . . . . . . . 2 . 3 Light condensate.. , , , , , , , , , 1.4
.
.
Mostly HCI Smelled strongly of ether, b u t was decidedly heavier (0.81 sp. gr.)
If t h e temperature of t h e pre-heater was raised appreciably above 150' C., there was much more light material given off, and t h e liquid delivered t o t h e still was lower in temperature, due t o decomposition with absorption of heat. At lower temperatures nearly as much was given off. When material t h a t had once passed through the pre-heater a t I j o o was again p u t through a t t h a t temperature, there was practically no further evolution of gas. This indicates t h a t t h e amount first obtained originally existed in t h e crude material. It was desired t o make a further examination of these impurities and of the decomposition products, but very little of this was done, on account of lack of time. SMALL SCALE MANUFACTURING SECTION RESEARCH DIVISION, C.W. S., U. S. A. AMERICANUNIVERSITY EXPERIMENT STATION WASHINGTON, D. c.
AN AUTOMATIC COMPENSATING FLOW METER1 By 0.G. OBERFELLAND R. P. MASE Received January 4, 1919
The flow meter described in this article was intended primarily for accurately controlling t h e gas concentration of gas-air mixtures. By gas concentration is meant the amount of gas (either by weight or volume) per unit volume of gas-air mixture. The flow of t h e gas-air mixture is measured a n d kept constant a t all times. Hence t h e matter of gas concentration resolves into t h e problem of maintaining a slow and very cons t a n t flow of t h e gas. The principle of gas feed control, which is used in most laboratories, depends upon maintaining a cons t a n t gas pressure against a small capillary opening. T h e matter of maintaining a constant pressure in relation t o atmospheqic pressure is a comparatively simple one, since t h e use of a definite head of liquid through which a small amount of gas is permitted t o waste, suffices t o keep t h e gas pressure constant. However, i t frequently happens t h a t experiments require a n arrangement of apparatus in which t h e outlet end of t h e capillary is not against atmospheric pressure b u t against a pressure somewhat higher. I n such cases t h e pressure against t h e outlet of the capillary invariably fluctuates more or less. Hence the problem becomes t h a t of maintaining a varying pressure on t h e inlet of t h e gas capillary such t h a t t h e pressure difference between t h e inlet a n d outlet is always constant. T h e apparatus evolved for this purpose is shown in t h e drawing. T h e apparatus as shown is in reality two such devices. T h e advantages t o be gained b y t h e double arrangement are: first, t h a t t h e concentration of t h e gas in t h e gas-air mixture can be changed from one concentration t o another almost instantly; 1 Published by permission of the Director of the Chemical Warfare Service.
