T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
Oct., 1916
TABLE 11-PEPSIN TESTSON EGGSOF UNKNOWN AGE BUT GUARANTEED “STRICTLYFRESH”
RESUME OF TESTS
PEPSIN-A
By HOWARD T. GRABER Received M a y 27, 1916
Assay Date 1915
I n a previous article’ entitled “Some Observations upon t h e Assay of Digestive Ferments,” I called attention t o t h e great variation in t h e apparent strength of a sample of pepsin due t o t h e age of t h e egg used in t h e test, and showed t h a t eggs between t h e ages of j t o 7 days leave t h e least residue when used in testing t h e strength of t h e pepsin. I therefore recommended, for uniformity in results, t h a t chemists adopt age limits for their eggs when testing pepsin, and it is interesting t o note t h a t t h e Revision Committee of t h e Pharmacopoeia, having confirmed these findings, have adopted this egg limit in their revised test for pepsin. The revised wording, which I have every reason t o believe will appear in t h e LT. S. P. I X test for pepsin, will state: “Immerse a hen’s egg, which should not be less t h a n 5 nor more t h a n 1 2 days old.” After having determined t h e large factor which t h e age of t h e egg bears in t h e assay of pepsin, it was of interest t o me t o know how my results would vary when choosing m y eggs as t o age and when going into t h e open market and buying “strictly fresh eggs” from a reliable dealer. I have compiled t h e results from a series of many tests. P a r t of these tests were made with eggs of known age ( 5 t o 1 2 days), a n d t h e balance with socalled “strictly fresh eggs.” The pepsin used in all these tests was a sample found t o leave a residue of about I cc. under ideal conditions a n d was chosen because of t h e fact t h a t it is easier t o note slight differences in strength with a residue of I cc. t h a n with a smaller residue. Assay Date 1915 2/13 15 19 20 22 25 26 4 5 8 in ~.
12 17 20
?6 31
TABLE I-PEPSIN TESTS ON Age of ResAssay A e o f Date Eggs idue kgs Days 1915 Days cc. 7 1.25 8 4/ 7 0.6 9 7 10 0.9 9 10 7 1.25 8 7 1.25 12 8 10 13 9 1.0 5 14 1.0 8 10 1.25 15 9 9 1.0 7 26 27 7 0.5 8 9 29 9 1.0 5 7 1.0 10 1.0 k 8
;
1 .o
1.5 0.55
14
21 22 26
11
11 7 10
EGGSOF Residue cc. 0.75 0.75 0.45 1.5 1.0 0.6 0.5 1.5 0.3 0.25 0.4 0.35 0.5 1.25 1.25 0.65 0.55 0.25
KNOWNAGE Assay Age of Date Eggs 1915 Days 10 10 12 10 10 10
7 7 7 7 14 1G 17 18 20
Residue cc. 0.6 0.4 0.4 1 .o
0.95 1.0 0.8 0.75 0.8 1.0 1.0 0.8 0.8 0.9 1.0 0.65
Table I includes a series of 5 0 assays from eggs of known age, a n d of this series we find: 28 assays (56 per cent) below 1 cc. 40 assays (80 per cent) not more than 1 cc. Of t h e latter 10, just 2 are THISJOURNAL, 3 (1911), 919.
10 assays (20 per cent) above 1 cc.
*
91 1
11/%
cc.
Residue Cc.
Assay Date 1915 10125 29 11/15 9 11
Res- Assay idue D a t e Cc. 1915 0.7 12/ 2 0.6 3 0.5 8 0.5 9 0.5 10 16 0 . 7 17 17 2 . 0 20 22 0.45 23 26 0 . 3 28 29 0.2 19 31 ( a ) Source of supply changed.
Residue Cc. 0.85 0.4 0.4 0.9 0.3 0.5 0.7 0.8 2.0 1.25 0 3
Assay Date 1916 1/10 13 14 17 19 28 2/ 5 7 4 6
Residue Cc. 1.0 0.6 0.9 1.25 0.3 0.65 2.5 3 2
Assay Date 1916 2/10 11 14 15 18 21 23 25 28
Residue Cc. 1.0 1.0
1.75
2 1 1.75 1 2.25 0.9
1.0
Table I1 includes a second series of jo assays from eggs supposedly fresh, but of unknown age. Here we find: 25 assays (50 per cent) below 1 cc. 32 assays (64 per cent) not more than 1 cc. 18 assays (36 per cent) above 1 cc.
Of these last 18 assays with a residue more t h a n cc., t h e largest residue recorded was 3 cc. Whether t h e eggs used in this test were too fresh, or, on t h e other hand, older t h a n t h e age limit previously described, I did not determine. The two tables show well t h e advantage accruing in choosing eggs of known age, a n d in t h e testing of pepsin as well as with rennin, I repeat m y caution“Know your standard.” Always use a standard pepsin as control, whose strength you have tested under different conditions as t o age of eggs, etc., and draw your conclusions as t o t h e strength of t h e unknown samples from t h e deportment of said control. I n concluding, I wish t o state t h a t in the above assays t h e conditions such as temperature, agitation, reaction, etc,, were under absolute control, and t h e error due t o t h e personal equation has been eliminated as far as possible. Another fact brought out in this connection which I have not heard discussed is this: If we can determine t h e strength of pepsin by the age of the egg, t h e contrary is also true. We can approximftely determine t h e age of a number of eggs by testing against a pepsin of known strength. If t h e residue is much more t h a n experience has shown t h e control t o run with eggs j t o 1 2 days old, i t is natural t o assume t h a t i t is due t o one of two causes: Either t h e eggs are absolutely fresh, or they are more t h a n 1 2 days old. If they are too fresh and one has supply enough, they can be kept for 5 or 6 days a n d another assay made. If with this second assay a marked decrease in t h e amount of residue is shown, t h e eggs can be considered as strictly fresh. If t h e residue continues t o increase, they were more t h a n t h e age limit t o start with and hence not strictly fresh I
RESEARCHLABORATORY, DIGESTIVEFERMENTS COMPANY DETROIT,MICHIGAN
LABORATORY AND PLANT ARTIFICIAL GAS-FIRED FURNACE INSTALLATION
fired furnace installation in this country has been made in t h e plant of t h e Eddystone Ammunition Corporation, Eddystone, Pa., for t h e purpose of hard-
ening and tempering (or drawing) 3-in. shells.
The
tempering furnace are a t present under COnStrUCtiOn a n d two each a t present in operation. The furnaces are arranged in units-one hardening and one tem-
T E E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C E E M I S T R Y
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pering furnace comprising a unit. Each unit is designed t o t u r n out 5,000 shells in a 20-hr. day. T h e full capacity of t h e installation (3 units) would be 15,000 shells per 20-hr. day. T h e furnaces are operating a t t h e high average efficiency of 3 2 per cent-furnace efficiency meaning t h e percentage of available heat units in t h e fuel consumed which are actually absorbed b y t h e work being done, in this case heating steel. The furnaces, designed a n d installed b y t h e Surface Combustion Company of New York City, are fired by t h e surface combustion high-pressure system-a process whereby gas under pressure is made, by means of a special governor, t o inspirate all t h e air necessary for complete a n d perfect combustion, maint a i n i n g , automatically, constant mixture OrODor. . L tions and eliminating all motors, blowers a n d air piping (Fig. 11). Gas under a pressure, Y rancinc from I O t o 2; Ibs. I I x D e r sa. in. uasses Eock, A, c o n t i n u e s t h r o u g h strainer, B, a n d enters nozzle, C. A portion of t h e pressure energy of t h e gas in passing from nozzle, C, into throat, D, is transformed into veloci t y energy. The pressure lkT5Panu head on air opening. E, is h r I, -thereby reduced, causing air t o flow first into air-chamber, F, and from thence into throat, D, where it joins with t h e gas. The high velocity a t t h e throat, D, mixes t h e air a n d gas thoroughly and t h e velocity head of t h e mixture is transformed hack into pressure head b y t h e pressure tube, G. The mixture then continues t o t h e burner.
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"hl
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The burners are inserkd a t the sides of t h e furnaces and incline downward. The homogeneous mixture of air a n d gas from t h e inspirator is forced through the burners a t a velocity greater t h a n t h e rate of flame propagation a n d each flame strikes a baffle consisting of carborundum or other refractory material resting on the bottom of t h e furnace. This material attains a n intense heat which is radiated very evenly upon t h e shells, from off t h e arched t o p of t h e furnace. Each furnace is approximately 22 ft. long, 8 ft. wide a n d 7 ft. high (outside dimensions) a n d is set on a slight slope. The furnaces are encased in cast iron casings held together by heavy tie rods and are mounted on concrete foundations. The heavy fire brick linings are backed up by Sil-0-Cel, giving plenty of insulation. This cuts down t h e radiation losses and protects t h e operators from t h e heat. The furnaces are a s air-tight a s possible. To prevent leakage in of cold air, which would produce a n oxidizing effect and, by its cooling action, lower t h e furnace efficiency, a slight furnace back-pressure is maintained. As in all surface combustion work t h e furnaces are so designed as t o develop and utilize t h e maximum possible amount of radiant heat. The flues a r e arranged so as t o distribute t h e hot gases uniformly a n d t o release t h e m at t h e lowest possible temperature. The hardening furnaces are equipped with zz high-pressure burners, a n d t h e tempering furnaces with 18. All piping is laid in conduits having removable covers, thereby eliminating all overhead work. To give a n idea of t h e simplicity of t h e system t h e largest pipe used is a z in. Each burner is fed by a '/*-in. pipe from a I-in. manifold. The fuel is a 580 B. t. u. gas (a mixture of water and coal gas), supplied by t h e Philadelphia Suburban Gas a n d Electric Company, Chester, Pa. The gas is delivered a n d metered under a pressure of 2 5 Ibs. It is metered by a Rotary pressure meter a n d a Bailey flow meter. Each unit consumes a n average of 3,300 cu. ft. of gas per hr., turning o u t 240 shells per hr., or 8
Oct., 1916
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
Rear (m discharge end) 01 Hardening F!~ns*. H o t shells pop out 01 opening. covered by iron Bnp on hinge mfo oil-Quenching tank. They arc removed from tank by elevator fonveyor to drain fables. and are them fed into T e m p s i n g (or drawing) Furnace.
shells every 2 minutes. Therefore, when all these units are running at capacity, 9,900 cu. ft. of gas per hr. would be consumed, and for a d a y of 24 hrs., 237,ooo cu. ft. of gas, and for 300 such days approximately 70,000,000 cu. f t . of gas. (While shells are turned out during only 20 hrs., the furnaces are kept hot the entire 24 hrs.) The cost of gas in this case is based on a sliding scale rate. T h e approximate average rate for this work is 43 c. per M. cu. f t . METHOD OF OPERATION
The shells made are 3 in. in diameter and approximately in. long. They vary in weight from 8 t o 1 1 Ibs. The hardening is done at a n average temperature of 1 5 0 0 ~F., and the tempering (or drawing) a t an average of 1100' F. Each shell is in each furnace for a period of approximately one hour. Running through each furnace are 8 steel angles which act as troughs t o carry t h e shells. An air cylinder with a n a r m attached t o the piston rod acts as a pusher. A man stands in front of each furnace and feeds shells into the angle troughs. Every 2 minutes the pusher pushes t h e shells ahead the length of a shell. This causes 8 shells t o discharge into the oil-quenching bath located at the discharge end of the hardening furnaces, from which they are taken when sufficiently cool and fed into t h e tempering furnaces i n exactly the same manner. Frequent flue gas analyses have shown oxygen = 0.0, carbon monoxide = 0.0, and a n average of I 5.2 carbon dioxide. This shows t h a t t h e heat is generated with IOO per cent efficiency having no excess air or unburned gases. For the purpose of minimizing t h e scaling of the shells and t o lengthen the life of the angle troughs the furnace is operated with a slightly reducing atmosphere-carbon monoxide reading between 0.3 and 0.5 per cent. This is done t o be on t h e safe side, as an oxidizing atmosphere would be very injurious in this operation. CONTROL
All of t h e furnaces are controlled from a central control pulpit. Each furnace is controlled b y a sin-
Rear Out
FIG.V end) 01 Tempering (or drawing) Purnseu. of tubes with B l p coven to keep out air.
(01 di.rhar$e
913
shells pop
gle valve which regulates the pressure supplied. The maximum pressure is 2 5 lbs. and t h e minimum 5 Ibs. The average operating pressure is 15 lbs. All pyrometers, both indicating and recording, are also located in this pulpit. This allows one man t o operate easily all of the furnaces. This feature has resulted in considerable saving of labor, since frequently as many as 8 men have been necessary t o care for burners and the control of temperatures on a similar number of furnaces of the same size, fired by oil. This feature also allows much more accurate and careful control as evidenced b y the practically straight line pyrometer charts which are secured daily. There is also located in this pulpit the electric flasher, which times the charging operation. This machine flashes a red light in front of each furnace every 2 minutes, which flash is the signal for the men t o operate the pushers. The furnace operator in the control pulpit, each shift, receives his temperature and time instructions and is able t o follow these instructions with the greatest accuracy without moving a step. This pulpit is the brains and heart of the heat-treating building, clock, bells, etc., all being located there. COMPARISON
WITH F U E L OIL
These furnaces are installed in the face of the competition of fuel oil costing 0.045 per gal. Several oilfired furnaces of practically the same size and doing the same work were in operation prior t o the installation of these furnaces. One of these oil-fired furnaces was carefully tested, over a period of several days, the oil being measured in a calibrated tank. Subsequent tests of the gas-fired furnaces have proven conclusively (as was believed in the beginning) t h a t t h e operating cost of the gas-fired layout is very considerably lower than t h a t of the oil. While i t is not argued t h a t all furnace operations can be done more economically with this sytem of gas-firing, still i t has been proven beyond doubt t h a t quite a percentage of large furnace work can be done considerably more economically than with oil. Generally speaking, 600 B. t. u. gas at 50 c. per M. compares very favorably with
T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
9=4
0.04 per gal. oil in a good many cases, using the surface combustion, high-pressure system in properly engineered and designed furnaces. For a plant putting in new furnaces where all the necessary equipment must be purchased, the initial cost of installation of this system of gas-firing will be found fully 30 per cent less t h a n the cost of the necessary equipment, including furnaces, for an oilfired installation. This system of gas-firing, eliminating, as it does, all air or steam supply and the consequent equipment for such, can be compared very favorably with even considerably higher priced fuels, as air and steam and the handling of them cost money, which is just as valuable as the money paid out for the actual fuel. The above figures, however, do not include any of these considerations but are based on straight fuel against fuel costs. LOXG ISLAND CITY
NLW
YOXK
SOME FEATUpES OF SWIMMING POOL CONTROL’ B y W. LEX LEWIS^ Received June 19. 1916
The responsibility for careful sanitary supervision on the part of those in charge of indoor swimming pools is increasing with the rapid increase in the number and patronage of these pools. Twenty years ago there were few indoor tanks. To-day, every upto-date gymnasium gives a large place t o this splendid feature of physical training. Almost every men’s club, many large hotels and some of the larger passenger steamers, maintain swimming pools. Moreover, there is a growing tendency among educational institutions t o require sximming as a part of the curriculum. This is true among the secondary schools of New York State and practically so a t Northwestern University; The University of Illinois requires of its men students the ability t o swim fifty yards. Princeton and Wisconsin require one hundred yards, and the navy a quarter of a mile. Obviously, enforced usage means definite legal responsibility for accidental infection traceable t o faulty sanitary control. Likewise, it must be noted t h a t , through health departments, school instruction, government publications, the press, etc., the general public is gaining a new knowledge of sanitary matters, and sanitary standards in all things are rising rapidly. The possibilities of an indoor swimming tank becoming unhygienic are apparent when one considers the intensive usage of a relatively small body of water and the absence of sunlight, fresh air, sedimentation and the various forces operative in the self-purification of outdoor waters. Furthermore. t h e coughing and spitting of the average swimmer is most favorable to contamination of the water with those disease germs typical of the respiratory tract, as those of tonsilitis, pneumonia, common colds and sore throat. Possible swimming pool infections might be grouped 1 Presented a t t h e 52nd Neeting of t h e American Chemical Society. Urbana-Champaign, April 18 t o 21, 1916. 2 A4ssistaiitProfessor of Chemistry, Sorthwestern University, and City Chemist, Evanston, 111.
Vol. 8, NO.
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under three heads: gastro-intestinal, respiratory and venerea1.l T o the second group should be added eye infections and possible infections of the skin and outer ear. Organisms causing such trouble would include staphylococcus, streptococcus, p n e u m o c o c c u s , B . coli, B. t y p h o s u s , gonococcus, etc. I n respect t o intestinal infections, i t has been repeatedly established t h a t these may follow bathing in contaminated water.2 An excellent review of t h e literature bearing upon this point may be found in a recent article by M a n r ~ h e i m e r . ~I n view of ‘ t h e demonstration of B . coli in swimming pool waters b y practically every worker in the field, the possibility of transmission of gastro-intestinal diseases is apparent. One point, in this connection, is the increasing recognition of typhoid carriers. Since the discovery of the famous “Typhoid Mary,”4 who infected 26 persons, some fatally, studies have been made showing the prevalence of such types. Rosenaus states t h a t ‘‘4 per cent of all typhoid fever patients continue t o discharge typhoid bacilli in the urine and feces during and after convalescence.” Albert states t h a t I person in every 1000 of population is a carrier. Studies by Lumsden and Anderson,G on the Washington population during which the feces of 1000 healthy persons were examined, led them t o conclude t h a t 0.3 per cent of the general population discharge typhoid bacilli. The American literature records no cases t h a t have come t o the author’s notice of actual diseases of this group proved t o have originated in swimming ~ 0 0 1 s . ~ Klein and Schutzj6 however, reported cases of typhoid fever in 6 soldiers mho had bathed in water close t o the mouth of a city drainage canal; 34 cases of enteric fever were reported among soldiers who had bathed in a swimming pool which derived its water from a polluted source.9 A4bout I O per cent of the men using the pool became infected, while only I case developed among those who did not use t h e pool. Baginskylo demonstrated 6 cases of typhoid infection as coming from a swimming tank. The epidemiology of swimming pools offers more direct evidence of infection from diseases in the second group. Baginsky“ reported several cases of rhinitis from a swimming tank. Fehr12 reported a number of cases of conjunctivitis among users of a public bath in Berlin. Burrage’s notes mild epidemics of Atkins, P Y O CI .l l . Ll’atev Supply Ass%., 1911. Jager, Z . H y g . , 12 (1892), 5 2 5 ; Pfuhl, Deutsche, M i l ~ l h ‘ d r a l l . Wochenschr., 17 (1888), H e f t 9 ; SchAfer, I b i d . , 17 (1888), H e f t 5 ; Lenhartz, Mtinch. l 4 e d . Wochschr., 21 (1892), 898; Klein and Schdtz, W i e n e v med. Wochschv., 6 (1898), 238; Drescher, Saniliilsbevichte iibev d i e Kgl. Preuss. rlrmee, 1898/99, I Teil, C. I. Gruppe 10 Unterabt. 3 Mannheimer, J . Infect. Dis., July, 1914. 4 Parks, “Pathologic Bacteria and Protozoa.” 5 Rosenau, “Preventive Medicine and Hygiene,” p . 83. 6 Lumsden and Anderson, Bull. H y g . Lab., U. S.P. H. S., 78 (1911). 7 Cf. Rettger and Markley, Eng, X‘ews, 66, 636; Whipple and Bunker, iMunic. J . , 31, 526. 8 Klein and Schiitz, Weiuev med. Wochschv.. 6 (18Y8), 238. 9 Illair. PYOC. R o y . Soc. M e d . , 2 (1908-9), Pt. 2, 2 2 7 . 10 Baginsky, H y g . Rundschau. 6 (1896), 597. 1
2
1’
Loc.
12
Fehr, Berlin klin. M’ochsrhr., 37 (1900), KO.1. Burrage. Proc. I n d . Acad. of Science, 1909; cf. Eng. Y e w s . 63 [ 2 5 ] , 740.
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