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INDUSTRIAL AND ENGINEERING CHEMISTRY
Vol. 19, No. 8
a liquid which will have practically the same molecular lower temperatures reactions occur which involve addition weight as the original oil but which will be progressively of oxygen with smaller molecular weight increase and greater depleted of its more reactive constituents. This liquid may reduction of the number of ethylene linkages. finally be absorbed by the gel particles. Disappearance of Both in the runs with the single glyceride and those with the liquid gives the phenomenon of setting. natural oils, the decrease in iodine number corresponding To test this theory of the final step in the setting of perilla to, say, a doubling of the molecular weight does not seem or linseed oil to a product usually spoken of as a gel, linseed to bear any fixed ratio to the total. Thus, for a doubling of and perilla oils were heated until this gelation occurred. the molecular weight the decrease in iodine number is apThe resultant gels were extracted with acetone in Soxhlet proximately 27 in both runs 71 and 72, but is 60 in run 69. extractors for 6 weeks. The extracted gels when thoroughly I n run 70 a t the higher temperature decomposition of the evacuated at 100" C. did not adsorb carbon dioxide at 20" glyceride, with consequent small gain in molecular weight, or 100" C., but when dropped into acetone solutions of the was accompanied by a large decrease in iodine number. liquid oil extracted from them by acetone, the gel took up When the linolenic monoglyceride is heated the weight the oil completely within the proportions contained by the of water evolved corresponds to 1 mol for each 2 mols of original glyceride. This suggests coupling of 2 molecules of original gel. It is conceivable that no coupling occurs and that the monoglyceride with elimination of 1 molecule of water. change when glycerides are heated in an inert gas or exposed The action does not seem to be so simple as this, for the water to radiations is simply a transformation to an isomer which evolved in individual periods shows a sharp decrease from happens to be a solid and which takes up oxygen and dries period to period in the case of this hydroxy body. It is more readily than the isomers in the original oil. It may suggestive that the weight of water evolved in run 73 is further be argued that the isomer which takes up oxygen approximately the same in each hour period. I n runs 73 and 74 the curves showing rate of change in most readily is the least receptive to halogen and that the decrease in iodine number can be explained on this basis. molecular weight indicate steady coupling of the molecules There are many features of the process not explained by to form dipolymers. It would seem that part of the water evolved must come from two OH groups within a molecule this mechanism, however. I n run 74 both the hexabromide and iodine numbers and only part by condensations of two or more molecules. decrease rteadily. The total decrease in hexabromide number Summary during this run corresponds to 0.080 X 0.367 = 0.0326 gram of that linolenic acid which forms a solid hexabromide. Relatively pure linolenic glyceride was prepared from If two of the ethylene linkages in each molecule have been perilla and linseed oils. saturated or rendered inactive by isomeric change, the deWhen heated a t 225" C. this glyceride seems to undergo crease in iodine absorption would amount to 0.0326 X a n isomeric change. At 250" C. coupling and condensation 12693 = 0.0594 gram of iodine per gram of oil. The reactions occur. At 293" C. this glyceride is rapidly de278.24 composed. actual decrease observed amounts to 0.319 gram of iodine Blowing favors reactions which decrease the unsaturation per gram of oil which is five times as great. This shows with relatively small attendant increase in molecular weight. that in the blowing of oil a t 138' C. the decrease in un- Heating favors coupling and condensation reactions. saturation cannot be ascribed merely to isomeric change. The use of liquid mercury surfaces in shallow pans of Further, the decrease in iodine number for a given molecular amalgamated tinned iron has many advantages in making weight increase is much greater than the corresponding de- oil films for study. The method is described. crease for an equal molecular weight change in the case of linseed oil heated at 293' C.; also the curve for rate of molecAcknowledgment ular weight increase has a smaller slope than the correThe authors gratefully acknowledge the help of J. G. sponding curve when oil is heated These data seem to indicate that when oil is heated a t 293" C. coupling and Smull, C. A. Knauss, D. V. Ransom, J. D. Ridsdale, and condensation reactions are favored, whereas when blown a t R. M. Roderick in obtaining these data.
Cereals and Rickets' By Harry Steenbock, Archie Black, and Byron H. Thomas UNIVERSITY OF WISCONSIN,COLLEGE OF AGRICULTURE, MADISON,WIS.
ITH calcium the fifth most abundant element in the earth's crust, it seems curious that animals should experience difficulty in finding a sufficiency of it for the construction and maintenance of normal skeleton. That such is the case is borne out by the general occurrence of rickets and of diseases comparable with rickets in man and in many domestic animals, such as pigs and chickens. Xot only are the young seriously deformed, hampered in their growth and made susceptible to other diseases by this affliction, but adults show increased fragility of bone and poor tooth construction, and often experience abnormal reproduction.
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1 Abstract of a paper presented a t the 7th Midwest Regional Meeting of the American Chemical Society, Chicago, Ill., May 27 and 28, 1927.
It is now generally accepted that rickets and its analogs are caused by dietary deficiencies. These may consist of a deficiency of lime, a deficiency of phosphorus, a disproportionality between calcium and phosphorus, or a deficiency of vitamin D, a highly active compound owing its physiological properties to ultra-violet radiation. It should be emphasized that the dietary requirements for calcium and phosphorus are not absolute. The amount required by an animal varies with the relative proportion of calcium to phosphorus and the presence of vitamin D. It is, indeed, highly probable that with suitable relation of calcium and phosphorus vitamin D may actually become wellnigh, if not entirely, dispensable. There is no question but that one of the causes of rickets
August, 1927
INDUSTRIAL AlVD ENGINEERING CHEMISTRY
in animals is the widespread deficiency of calcium and the less prevalent or only occasional deficiency of phosphorus in food materials. Under ordinary conditions none of our cereal grains, for example, contain a sufficiency of calcium for adult man when consumed as the sole article of food. Only a liberal consumption of milk, eggs, or vegetables corrects this difficulty. Polished rice, pearl barley, wheat farina, and patent wheat flour are notoriously deficient, and of these polished rice and patent flour are deficient in phosphorus as well. That cereal grains and their starchy products mill produce rickets is generally admitted, but the time has arrived when nutritionists are no longer content with pointing out the novelties of special edible materials, such as yeast, cod-lirer oil, and orange juice. They are now concerning themselves with the determination of small marginal differences in the nutritive value of those materials which go to make up the major portion of the food of various peoples. I n 1925 Mellanby, of Sheffield, England, reported that of different cereal products-namely, barley, oatmeal, rice, white flour, wheat, and maize-oatmeal is the worst offender in the production of rickets in puppies, and white flour the least. To explain these findings, so a t variance with the personal experience of the Scotchman and with what is to be expected from mineral analyses, Mellanby assumed that in oatmeal there is present a certain toxic factor which he speaks of as a toxamine. At the time of the appearance of Mellanby's report ex-
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periments with rats carried out in the author's laboratory did not support Mellanby's contentions. Since then many hundreds of rats and eighty-three dogs have been used to study these relations in greater detail. With careful attention paid to litter mate controls, and food consumptionusing general appearance of animals, growth, x-ray examination, chemical analysis of blood, ash analysis of bone, and histological examination of costochondral junctions as the criteria, it has been impossible to demonstrate that rolled oats is especially rickets-producing. I n fact, rolled oats has shown itself to be on the average somewhat less ricketsproducing than maize in both dog and rat experiments, but somewhat more so than wheat in the trials with rats. All the tests carried out with dogs, which are exceedingly su+ ceptible to rickets, show that all cereals are so decidedly rickets-producing that a large number of trials with very carefully executed controls are necessary to demonstrate which is the worst. I n any case the defect of the cereals can be remedied by the judicious supplemental use of foods high in calciuniand also high in phosphorus in special instances-and by the treatment of the cereal with ultra-violet radiations. By the latter means vitamin D can be produced in abundance so that even without mineral additions a rachitic condition can be much improved. Knowledge of these facts makes it possible to use cereal grains and their products for human and animal nutrition to the greatest advantage.
A Critical Analysis of Equations for the Design of Fractionating Columns'vz By Loren H. Shirk and Ralph E. Montonna SCHOOL OF CHEMISTRY, UNIVERSITY OF MINNESOTA, MINNEAPOLIS, MINN.
URING the past five The various proposed rectification equations have e a s i e s t and most rapid to years the rapidly inbeen subjected to critical analysis. apply to the desired problem. creasing literature in The method of McCabe and Thiele has been found to It seemed desirable, therethe field of chemical engineerbe the most Practical and accurate for use in column fore, to secure experimental designdata on a scale approaching ing has contained numerous a r t i c l e s d e a l i n g with the A n apparatus has been designed to Secure the data plant conditions and toapply theory of fractiollation and necessary for a Comparison of the methods of Calculat h e m o s t promising equavarious equations have been tion of the number of Plates required for a given SeParations to these data for the d e v e 1o p e d by different intion. purpose of finding out which vestigators for the calculation Data showing the over-all efficiency of a bubbler-caP o n e s m o s t nearly approxiof the theoretical number of plate column with alcohol-water mixtures under mated the results and how various conditions have been obtained. plates or length of column close an agreement was to be required for a given separaA method of determining the Percentage of alcohol expected for the particular tion, hiost of these equain extremely dilute waste liquors has been devised. system chosen. tions have been based upon The criticism of mathematical methods which asT h e s y s t e m water-ethyl a very limited amount of exsume COntinUOUS instead of stepwise conditions has alcohol was chosen for study, perimental data, and there is been Shown to be justified. for several reasons. It is a little evidence to show the common commercial mixture engineer seeking to use them for the practical design of stills and data might be of practical use; results would be more how well they actually represent the conditions of plant prac- comparable with those of other investigators, most of whom tice. Furthermore, the multiplicity of methods leaves the have worked with this system; reliable liquid-vapor equidesigner in doubt as to which one would give the best ap- librium data3 are available for the range covered by this proximation of plant conditions and a t the same time be the investigation; and finally, simple, accurate, and reliable analytical methods are 1 Presented before the Division of Industrial and ~ ~ ~,-hem- i ~ ~ ~ f i known. ~ ~ A suitable still was designed istry at the 72nd Meeting of the American Chemical Societv. PhiladelDhia. and the column constants for different ethvl alcohol-water . Pa., September 5 to 11, 1926. mixtures were determined with varying an; carefully conAbstracted from a thesis submitted b y Loren H. Shirk to the faculty trolled rates of distillation and reflux ratios. Using these of the Graduate School of the University of Minnesota in June, 1926, in Constants, the theoretical number of Plates required for the partial fulfilment of the requirements for the degree of master of science in
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chemical engineering.
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THIS JOURNAL, 12, 496 (1920); 13, 168 (1921).
