Sept., 19.22
T H E JOURNAL OF INDUSTRIAL A N D EXGIXEERING CHEIMISTRY
orous examination of the explanations for them, so that ultimately we shall know a good deal more of the truth. Meanwhile, the arguments pro and con will continue to make the discussions of metallurgical papers lively.
CONCLUSION The above represents the personal “reaction” of the reviewer on the more important features of nonferrous alloy progress in 1921. iinother reviewer might pass over most of these and cite many other developments, commercial and scientific. The interested reader will find the detailed
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nonferrous history of 1921 in the following (rated in classes according- to usefulness to the writer). Class 1-Transacttons of the Amerzcan Institute of Mining and Metallurgical Engineers, Journal of the Institute of Metals (abstracts valuable as well as papers, Most of the abstracts available in Chemical Abstracts but more readily used in J . Inst. Metals on account of beina collected and classif i e d ) ; Chemical and Metallnrgzcal Engineering. Class 2-The Foundry; The Iron Age (contains many nonferrous data); Metal Industry ( N . y.); Metal Industry (London). Class %--Revue Metallurgic; Zeitschrift f d r M eiallkunde, Engineering (London). Class 4-Brass World: Metal1 und Erz.
Physical Chemistry as Applied t o Foods By Carl L. Alsberg DIRG-CTOR, FOOD RESEARCH INSTITUTE, STANFORD UNIVERSITY, STANFORD UNIVERSITY, CALIF.
HE SLOP JAR used to be the destination of most of the
teins known as gluten, which, when mixed with water, forms colloidal substances the chemical investigator encoun- a tenacious, elastic mass. For this reason wheat and, to tered. What did not crystallize he stigmatized as a a less degree,.rye alone of all the grains yield dough. Besmear. Yet what does not occur in nature in the crystalline cause of the physical qualities of gluten-its toughness, its form is at least as important to man,as what crystallizes, for it distensibility, and its coagulability by heat-it is possible constitutes the essential portion of organized beings. Until to produce leavened bread. These qualities of glutenwell toward the end of the last century only the biochemist elasticity and coagulability-however, are physicochemical, or the physiologist concerned himself with such material. not purely chemical qualities in the ordinary sense. They It was necessary for the biochemist to pioneer in this field do not depend primarily upon the arrangement of the atnins and for the science of physical chemistry to have developed in the molecule but rather upon the physical condition of before the study of such colloidal, not readily crystallizable molecular aggregates. If, then, the properties of gluten material became interesting to chemical investigators gener- which render wheat so desirable as a bread grain are physicoally. Solely by means of the application of the principles chemical, they depend upon the physicochemical condition of physical chemistry to the study of the colloidal materials of the protein molecule, not upon its chemical structure. It that characterize living organisms has progress in many is not too much to hope that physicochemical research branches of biological science become possible. Such phe- upon colloids will one day enable us to control the colloidal nomena as the acid-base equilibrium in animals and plants, state to such an extent that we can give to a colloid essenthe maintenance of neutrality, the transport of carbonic tially those physicochemical properties that we desire. If acid through the blood, the mechanism of secretion and this can be done, and there is no inherent impossibility in the excretion, cell respiration, the osmotic phenomena exhibited idea, it may be possible to give to other proteins besides by living isemi-permeable membranes, and the metabolism of gluten the physicochemical properties of gluten. When microorganisms came to be understood only when con- that time comes, leavened bread will be produced from ceptions of physical chemistry began to be applied by the materials or grains other than wheat and rye. What this biochemist in the study of biochemical phenomena. Stud- would mean to the food supply and the future of the race is ies upon i,he true character of acidity and alkalinity, upon obvious. Indeed, before such profound developments take dissociation, the phase rule, emulsions, sols and gels were place, it is probable that the application of physical chemistry necessary before some of the apparently simpler problems to the food industries will render them vastly more efficient. of biology could be studied. It is fair to say that to-day the To-day the milling and baking chemists are studying the science of general physiology is based very largely upon the hydrogen-ion concentration of milling and baking materials science of physical chemistry. Each advance in physical and are coming to realize that this is one of the most imchemistry is liable to be followed by a corresponding broad- portant, if not the most important, factor in determining ening of our knowledge of the behavior of living things. the bread-producing qualities of flours and the behavior of It is obvious that only through such knowledge can progress doughs in fermentation. It is not improbable that in the be made in many branches of medicine. Thus, to physical milling laboratories of the country the potentiometer before chemistry must be attributed much of what we know about long will be as familiar an instrument as the buret. TI7hat the coma [,hat may result from the disturbance of the acid- is likely to be true in the mill is likely to be true in the bakery, base equilibrium in the body, which the pathologist knows in the creamery, and in the sugar refinery. The behavior of as acidosis, so common a cause of death, especially in diabetes. dough and yeast is profoundly influenced by physicochemical Since agriculture and food manufacture are essentially conditions. Butter is an emulsion. The colloids of cane forms of applied biochemistry, physical chemistry has made and beet juice play an important part in molasses formation, possible great advances of immediate practical usefulness. while the problem of decolorizing carbon is one for the physiWithout physical chemistry our present-day conceptions of cal chemist. Examples might be multiplied vastly, were the equilibria that prevail in soils and in the soil solution space available. It is perhaps sufficient to add, in concluwould be impossible. An increase in our knowledge of the sion, that most of the industries that elaborate raw materials behavior of colloids and of emulsions is destined to influence derived from living beings have to deal with colloids. Thereprofoundly the lvorld’s methods of food production. For fore they can make progress only so fast as they apply to example, wheat owes its preeminence as a bread grain in their problems the discoveries made in that branch of physilarge measure to the fact that it contains a mixture of pro- cal chemistry which is known as colloid chemistry.
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