Identifier: physiologybioche00macl (find matches)
Title: Physiology and biochemistry in modern medicine
Year: 1918 (1910s)
Authors: Macleod, John James Rickard, 1876-1935 Pearce, R. G. (Roy Gentry), 1884-
Subjects: Physiology Biochemistry
Publisher: St. Louis : Mosby
Contributing Library: Columbia University Libraries
Digitizing Sponsor: Open Knowledge Commons

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re water. This is known as the freezing point constant,and it varies for different solvents, being 3.9 for acetic acid and 4.9for benzene. If an unknown watery solution is found to have a freez-ing point that is A0 C. lower than that of water, its osmotic pressure :11 . A x 17.024will equal ——^ mm. Hg. 10 osmotic ii;i:ssi:i;i: 11 The depression of the freezing points produced by the various bodyfluids has been compared, the objects in view being to see whetherosmotic pressure is a property which changes under different physiologic and pathologic conditions, and to find out by comparison of the osmoticpressures of the Quids in contact with a membrane, whether physicalforces alone can be held responsible for the transference of substancesthrough it from one fluid to the other. The Role of Osmosis, Diffusion, and Allied Processes in Physiologic Mechanisms An account of some of the investigations in which the foregoingmethods have been used will illustrate their value in revealing the
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Fig. 4.—Apparatus for measurement of the depression of freezing point of solutions. Thesolution is placed in the large test tube with the side arm, and in it is suspended the bulbof a Beckmann thermometer with a platinum loop to serve for stirring. The upper end ofthe mercury column of the thermometer is shown magnified at the upper left corner. Theamount of mercury in the thermometer tube can be regulated by tapping the upper end withthe thermometer in various positions. The test lube is protected by an outer tube, which isthen placed in a vessel containing a freezing mixture. mechanism involved in the transference of water and dissolved sub-stances through cell membranes, as occurs in absorption of food in theintestine, in the formationof lymph and urine, and so forth. In em-ploying physical methods in the elucidation of such problems, it isalways most necessary to proceed with great care, since the physical 12 * PHYSICOCHEMICAL BASIS OP PHYSIOLOGICAL PROCESSES chemist works with

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