March, 1!324
INDUXTRIAL A N D ENGINEERING CHEMISTRY
harmful effects from a too rapid rise in temperature. It is well known that if the soaking of apples is conducted a t too high temperatures the centers become darkened. With some varieties this occurs as low as 54” C . (130OF.). When some varieties of strawberries are canned immediately after being taken from cold storage, the oxygen content is high due to inhibited respiration a t the low temperature and the bright red color is deadened by too rapid heating.
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There are no data available to show a t what temperature the respiratory processes in fruit are destroyed. It undoubtedly varies with conditions and variety of fruit. Moreover, variable factors are always at play, control of which is difficult and often impossible. Different sets of conditions may give what on the surface appear to be contradictory results. It is of the utmost importance that these conditions be clearly understood.
Studies of the Vitamin Potency of Cod-Liver Oil’ VI-The
Effect of Storage of Livers on the Vitamin A Potency of Cod-Liver Oil By Arthur D. Holmes E. L. PATCHCo., BOSTON,MASS.
while the oil from the stored ES’L’S of the vitamin Cod-liver oils were rendered from fresh cod livers, from livers that livers showed a progressive potency of commerhad been stored six months, and from livers stored one year. increase in the red color, in cial cod-liver oils The results of three series of comparable tests in which albino rats all probability due to an inshow that in order to obtain suflering from Vitamin A starvation were fed graduated amounts creased absorption by the cod liver of highest potency of the three oils noted above, showed that oils from livers which had oil of liver decomposition it is necessary to render the been stored at a low temperature out of contact with air had as high products. cod livers as soon as possible a vitamin potency as oil rendered from fresh livers. I n order to provide data after they are removed from One milligram per day of each of the oils contained su$icient concerning the effect of the fish. Accordingly, in vitamin A to insure good growth In albino rats. storam of cod livers on the attempting to improve the nature of the oil obtained process of manufacture of cod-liver oil, attention has been centered on the type of equip- from them, analyses were made of the three oils in question. ment and the manufacturing conditions that permit most rapid The results of the analyses are given in the table. rendering of cod livers. However, in some plants it has been AND PHYSICAL CHARACTERISTICS OF OILS FROM STORED LIVZRS necessary to ice cod livers and hold them for a day or so in CHEMICAL Oil from Oil from Livers Oil from Livers order to secure a sufficient quantity for the economical operaFresh Livers Stored 6 Months Stored 1 Year gravtion of the rendering equipment. This practice naturally Specific 0.917 0.Q18 ity at 25’ C. 0.919 inraises the question as to what effect “icing” livers has on the Refractive 1.4775 1.4789 dex at 20’ C. 1.4789 vitamin potency of the oil obtained from them. Saponification value 183.400 182.400 185.100 T o secure definite data in this connection, a supply of Iodine value 142.700 154.500 142.700 0.5903 per cent 15.560 per cent 18.070 per cent fresh cod livers was divided into two equal lots, one of which Acid value Owing to a limited supply of o i l s under consideration, the usual colorwas rendered at once. The second lot was put in a glass imetric analysis was omitted. container in a n icebox. Six months later the livers were still FEEDING TESTS of a normal, cream-white color, although some bloody water had separated at the bottom of the container. However, The method followed in determining the vitamin potency when the container was opened, no odor of decomposition of the oils described here was identical with that which has .could be detected. During the 6 months that the livers been described in earlier reports.2 Young, growing albino had been on ice, some oil had exuded from them. rats were fed a synthetic diet adequate except for fat-soluble A quantity of this oil sufficient for vitamin tests was re- vitamin until they had exhausted their body reserve of vitatnoved after which the container was again sealed and placed in min A. At this stage three groups of rats were fed graduated the icebox for another 6 months. For a portion of the extreme amounts of the three oils under consideration. In these tests, cold weather of the second 6 months the livers were frozen. as is the custom, the oils in question were fed separate from and Even after the livers had been stored for a year, they appeared as a supplement to the usual synthetic diet, the composition t o be in fair condition. The external portions of some of the of which has been previously reported. By this means a livers had changed from the normal cream-white to a red color. uniform daily intake of oils is secured, which is found imWhen the container was opened, the livers had a detectable possible if the cod-liver oil is incorporated in the regular but not pronounced, unpleasant odor. Probably this preser- basal diet, for experience shows that during the period of a vation of the livers was due in part, a t least, to the small test a rat’s food consumption fluctuates over wide limits. amount of air in the container. The oil that was obtained POTENCY OF OIL FROM FRESHLY RENDERED LIVERS from the livers which had been in storage for a year had about t h e same viscosity and color as oil produced by the short time Referring to Chart 13, which reports the results of tests of C( rotting process.” The oils that were obtained from the freshly rendered the vitamin potency of the oil rendered from fresh cod livers, livers, from the livers that had been in storage for 6 months, it will be noted that nine animals were used in this test. and from the livers stored for a year, were of noticeably dif- When the physical condition of these animals indicated that ferent colors. The oil from the fresh livers was straw-yellow, they had exhausted their body reserve of vitamin A, their usual diet was supplemented by cod-liver oil varying in 1 Presented before Division of Biological Chemistry a t the 66th Meeting amounts from 0.00024 to 0.0048 gram daily.
T
af the American Chemical Society, Milwaukee, Wis., September 10 to 14, 9923.
2
J . Metabolic Research, 2, 113 (1922).
ILVDL'STRIAL A N D ENGINEERING CHEMISTRY
296
1
bITAMIN'POTENCC
1
O F C d D L i V E R ' 01
F R O M FRESH LIVERS
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,
1
V l l A M i N P O ~ ~ ~ ~ ~ , ~[ ~ ~1 ~ ~ ~Chart ~ ' V 14~ ~ ~ I
STARTED COD LIVER OIL -
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VITAMIN POTENCY
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j
I
l
OF COD LIVER OIL
FROM L I V E R S STORED ONE "CAR
Chart 15
I
i
Rats 189 and 196 received 0.00024 gram of oil per day, but were unable to recover from the effects of vitamin A starvation and subsequently died. When Rat 174 showed the first signs of vitamin A starvation, its diet was supplemented with 0.00048 gram of oil daily. For 20 days this animal continued its previous rate of growth, but during the next 25
Vol. 16, No. 3
s
STARTED COD LIVER OIL
days the net gain in weight was only 2 grams. After 45 days the test was discontinued and the animal was transferred to the stock diet, which caused it to make very rapid and continued growth. When the diet of Rat 187 was supplemented with 0.00072 gram of oil daily, it was able to resume its growth for 25 days. For the next 20 days it maintained its body weight, after which it soon died, showing that for this animal, a t least, 0.00072 gram of the oil in question did not contain sufficient vitamin A to meet its needs for growth. Rat 95 showed definite evidence of vitamin A starvation by its consistent loss of weight for 3 weeks; yet on the addition of 0.00096 gram of oil daily to its diet, it soon commenced very rapid and continued growth. In general, it was found that those animals receiving 0.00096 gram or more of the oil daily were able to recover from their malnutrition and gain weight rapidly. From these observations it is concluded that the daily consumption of 0.00096 gram of this oil provides sufficient vitamin A t o meet an albino rat's requirements for growth. POTENCY OF OIL FROM LIVERSSTORED 6 MONTHS The results that were obtained with ten animals in tests of the oil from livers that had been stored 6 months showed it to have a potency equal to oil from fresh livers. R a t 197 was able to maintain its body weight for 10 days on 0.00024 gram oil daily, but after this it failed for 18 days and died. Rat 176, which was fed 0.00048 gram of oil daily from the first evidence of vitamin A starvation, was able to maintain its body weight for 45 days, when the test was discontinued. In a check test, Rat 228, which experienced a greater decrease in body weight before the oil was added t o its diet, failed for 25 days and died. Two rats, 188 and 214, received 0.00072 gram of oil daily, but failed for 35 days and 25 days, respectively, and then died, The remaining five animals, which received daily doses of 0.00095 to 0.00475 gram of oil, all recovered
March, 1924
INDUSTRIAL A N D ENGINEERING CHEMISTRY
and grew a t a rapid rate. On the basis of these tests, it is evident that the oil from livers stored 6 months is fully as potent as that from fresh livers.
POTEKCY OF OILFROM LIVERSSTORED ONE YEAR The rcmlts of tests of the potency of cod-liver oil obtained from livers which had been in storage for slightly over a year are of particular interest. I n these tests (Chart 15) seven animals were fed oil in amounts graduated from 0.00022 to 0.00312gram daily. All these animals promptly responded to the addition of oil to their basal diet. When this series of tests was started, it was questioned whether as little as 0.003 gram of this type of an oil contained enough vitamin to keep a rat alive for the 45-day experimental period, and from past experience it seemed certain that those animals receiving less than 0.001 gram daily could not live long. Consequently, Rat 222 was included in the series as a check on Rat 204. The results of this series show that in one instance, a t least, as little as 0.00022 gram daily of the oil obtained from livers
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that had been stored for a year containedsufficient vitamin A to meet the requirements of albino rats for growth. It may be noted, however, that the oil rendered from the stored livers was decidedly less palatable than the oil obtained from the fresh livers. As regards appearance and palatability, the oil from the stored livers resembles oil obtained by the “rotting” process and is not in the least comparable to oil rendered from fresh livers. Comparing these results with those obtained from the study of oil rendered from fresh livers, it appears that cod-liver oil rendered from cod livers which have been stored a t a low temperature’and out of contact with the air has a higher vitamin A content than that rendered from fresh livers. The investigation of the effects of storage of livers on the vitamin A potency of oil obtained from them is being continued. The results of tests of the vitamin potency of oil rendered from livers which were stored in open containers and exposed to atmospheric changes mill be reported in a separate paper in the near future.
Simplification of t h e Separation of Zinc from Iron and Aluminium‘ By E. G. R. Ardagh and G. R. Bongard c N I V E R S r T Y OF T O R O X T O ,
TORONTO, CANAL4
HE: determination of At one time Kansas, Zinc can be separated completely from iron, and also from Missouri, Illinois, and Indizinc in ores always aluminium. by ammonium hydroxide and ammonium chloride .ana smelters could comnecessitates its sepain one precipitation. Two-tenths of a gram of each metal, or even mand a supply of ore averagration from iron. This is more, can be handled with celerity and ease. ing 0.5 to 1.5 per cent iron. usually accomplished (1) by Iron and aluminium hydroxides are precipitated in a compact While, it is true, conditions repeated precipitation of the state by evaporating their solutions to a oery small oolume, adding iron by ammonia, (2) by have changed, ample promore than suficient ammonium chloride to saturate the solution, vision has been made for ammoiiiuni carbonate, (3) and then adding concentrated ammonium hydroxide in considerablc much higher iron content by M basic acetate, or (4) by suction the erecieitate is casu to wash. excess. Bu using- gentle precipitation of zinc as zinc employing in the great sulfide in weakly acidified majority of experiments 0.2 solution. Not only are all these processes, as usually carried gram iron and 0.2 gram zinc, corresponding to 40 per cent of out, time-consuming, but in methods (3) and (4) the condi- each metal when 0.5 gram is taken for assay. Ingalls’z states tions m m t be maintained within quite narrow limits to insure that low-grade calamines assaying 40 per cent ferric oxide (28 per cent iron) have been smelted, but that with this exsuccess. It is the purpose of this article to show that perfect separ- ception no ores containing over 20 per cent iron are acceptable ations can be made quickly and conveniently with ammonia to zinc smelters. A .European smelter would rarely care, and ammonium salts, even when relatively large quantities says Ingalls, to have more than 10 per cent iron in his charge. I n New Jersey the ore smelted a t the present time contains 2 of the two metals are present at the same time. The determination of zinc in ores in North America is to 3 per cent iron, while the same authority says that in invariably carried out volumetrically by the ferrocyanide Kansas and Missouri probably few smelters carry more method. The method was first proposed by Galletti,2~* than 2.5 per cent iron in their charges. and the modification in use today is very well described in STANDARD SOLUTIONS A N I DETERMIKATIOK OF THE BLANK Low’s4 “Technical Methods of Ore Analysis.” Schaffner’s The standard ferrocyanide solution contained about method‘ never attained any vogue on this continent. Of all the authorities on the determination of zinc, A. H. 22 grams potassium ferrocyanide and 8 to 10 grams sodium Low is the only one who could be found who maintains that thiosulfate per liter.5 It was checked every 2 weeks against this metal can be completely separated from iron (when the pure ZnS04.7HzO solution containing 44.000 grams of the latter is present in more than very small amount) by ammonia pure salt per liter. One cubic centimeter of this solution and ammonium chloride by a single precipitation. All contained 0.0100 gram of zinc. The indicator used conother writers declare a double precipitation to be necessary. tained 15 gram UO(NO& in 100 cc. of water.lO To test the influence of varying the concentration of the Low states that zinc can be completely removed from precipitated ferric hydroxide by washing with a solution contain- ammonium chloride on the blank, a series of trials was made ing 100 grams ammonium chloride and 50 cc. concentrated in which the other factors were kept constant. ammonium hydroxide per liter, but he does not give any conNH&1 Added , KdFe(CN)s Required firmatory figures, nor state how much iron was present when TRIAL Grams cc. 1 5 0.16 lie carried out the experiments that led to his conclusion. 2 10 0.15
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1 Received
3
July 2 5 , 1923.
* Numbers in text refer to bibliography a t
end of article.
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