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. TABLE I-PEPSIN TESTS ON EGGSOF KNOWNAGE Assay Date
1915 2/13 15 19
20 22 25
26 4 5 8
in ~.
12 17 20
?6
31
Age of ResEggs idue Days c c . 7 7 7 7 7
10
5 10 9 7
1.25 0.6 0.9 1.25 1.25 1.0 1.0
1.25 1.0 0.5 1.0 1.0 1.0 1 .o 1.5 0.55
Assay Date
1915
4/
;
A eof kgs Days
9 10 12
13
14 15
26 27 29 5 7
8 9
0.75
10 8 8
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
9 8 9 7 8 9 9
k
10 8
21 22 26
11 7 10
14
Residue cc.
11
Assay Age of Date Eggs 1915 Days 10 10 12 10 10
0.75
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 the latter 10, just 2 are THISJOURNAL, 3 (1911), 919.
10 assays (20 per cent) above 1 cc.
*
91 1
11/%
cc.
Residue Cc.
Assay Res- Assay Date idue D a t e 1915 Cc. 1915 10125 0 . 7 12/ 2 29 0 . 6 3 11/15 0 . 5 9 0.5 11 0 . 5 16 0 . 7 17 2 . 0 22 0.45 26 0 . 3 29 0.2
( a ) Source
of supply changed.
Residue Cc.
0.85 0.4 8 0.4 9 0.9 10 0 . 3 17 0 . 5 20 0 . 7 23 0 . 8 28 2 . 0 19 1.25 31 0 3
Assay ResDate idue 1916 Cc. 1/10 13 14 17 19
28 2/ 5 7 4 6
1.0 0.6 0.9 1.25 0.3
0.65 2.5
3 2 1.0
Assay ResDate idue 1916 Cc. 2/10 1 . 0 11 1.0 14 1 . 7 5 15 2 18 1 21 1.75 23 1 25 2.25 28 0 . 9
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
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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-
