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It is remarkable that the increases in ammonium-ion activity produced by the diammonium phosphate are in some cases even less than those of the hydroxidc, which themselves only amount to some 5 to 7 per cent of the totals added. Further work will be needed to establish the exact cause of this anomaly. A peculiarity of additions of both acctate and phosphate was that equilibrium required 48 hr. for its attainment, whereas the chloride and hydroxide sholyed no change after 12 hr. As regards the larger additions of ammonium chloride, it will be seen that the additional ammonium-ion activit,y measured is roughly that of the salt itself, so that we may again conclude that, to a first approximation, the presence of the polyvalent colloidal anions does not affect the act,ivity of monovalent ions in true solution. At higher concentrations of clay, however, surh an effect might perhaps be large enough to measure. SUMMARY
1. It has becn shown that, the clay membrane electrode (hydrogen montmorillonite dried a t 490°C.) can be used to measure ammonium-ion activities below 0.1 .\-in solutions in which it is the only monovalent cation and in which the
concentration of divalent ions is less than that of the ammonium ion. Hydrogen ions interfere, but a correction can be applied provided the membrane is not attacked. The p H should be over 4. 2. Titration curves n-ith ammonium hydroxide have been obtained for the following clays: Putnani (Iieidellite), Wyoming bentonite (montmorillonite), illite, and kaolinite. 3. Ammonium salts of weak acids or of high initial pH lose ammonium. ions to the clay in much the same way as does ammonium hydroxide. The activity of ammonium ions from ammonium chloride is not affected by the presence of the polyvalent clay anions within the rangc studied. REFERESCES (1) MARSHALL, C . E., A N D B E R O X A W. K , F, m. C!hem. SOC.BS, 1911 (1941). (2) MARSHALL, c. E., A N D BERo!,raa, W . E.: ,J, Phys. Chem. 48,52 (1942).
COhlNI‘SICXTIOS TO T H E EDITOR REVERSIBILITT O F HEAT DEKATURATION OF PROTEIK
Sir: In a recent paper by M. Spicgel-Adolf and G. C. Henny (J. Phys. Chem. 46, 931 (1941)) it is stated that “Reversibility of heat denaturation appears to be limited to serum albumin. S o reversibility has been detected so far in other proteins submitted to heat dcnaturation.” Reversihility of heat denaturation has, in fact, been demonstrated in other proteins,-in hemoglobin by A . E. Mirsky and 11.L. Anson (J. Gen. Physiol.
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13, 133 (1929)), in trypsin by J. H. Sorthrop (J. Gcn. l'hyeiol. 16, 323 (1932)) and 11.L. Anson and A. E. Rlirsliy (J. Gen. Phyaiol. 17, 393 (1934)), in chymotrypsin by A I . Kunitz and J. H. Sorthrop (J. Gen. Physiol. 18,433 (1935)), and in pepsinogen by R. 11. Hcrriott (J. Gen. Phyqiol. 21, 501 (1937)). M. L. ANSON. A. E. MIRSKY. Rockefeller Institute for Medical Research Princeton, S e w Jersey, and New York, S e w York. Received October 1, 1941.
KEW BOOKS The Analytical Chemistry OJ Industrial Poisotis, Ilazards and Soluents. B y MORRISU. J.AC.OSS (formerly Chemist in the Food and Drug Administration, U. S. Department of Agriculture; formerly Chemist in the Dcpartmcnt of Health, City of Kew York; and formerly Lieutenant, Chemical Warfare Service Reserve). (This book constitutes Volume I of A Series OJ Monographs o n Analytical C ' h i i s ! r j / and its Applications, edited by Beverly L . Clarke, I. M. Kolthoff, and Hobart €1. Willard.) 6 x B+ i n . ; xviii 661 pp.; 110 illustrations; 33 figures. Xew York: Interscience Publishers, Inc., 1041. Price: 17.00. The author has given a n excellent comprehensive resunid of thc principal industrial hazards caused by toxic dusts, gases, vapors, and liquids, the chief industries in which each toxic agent occurs, the symptoms caused by i t , the methods of collecting samples, and the microscopic and chemical tests, both qualitativc and quantitative. Thc discussion of each toxic agent is introduced by a rather brief and correspondingly incomplete statement of the industries in which i t is encountered, and a brief account of the toxic effects upon the organs and functions of the human body; in the writing of the latter the author has had the advice of Professor E. P. Pick, formerly Director of The Pharmacological Institute of The Cniversity of Vienna. The concentrations of the substances in air and the amounts which are dangerous and lethal are usually given. The analytical mcthods are presented clearly and completely with citation of the original sources, a n d for most toxic agents several of the best methods of analysis are described. Thc section on the general methods for collecting and adsorbing samples of toxic or irritant dusts and gases and on the quantitative methods of determining and calculating the size and numbers of dust particles i s well presentcd and well illustrated. The section on the microscopic examination and estimation of silica in dusts is particularly good. This is followed by chapters on the dangerous metals, lead, mercury, arsenic, antimony, chromium, manganese, selenium, thallium, zinc, tin, nickel, and on the radioactive substances. These chapters are folloircd by sections on the gaseous poisons commonly encountered in the industries, such as chlorine, phosgene, hydrochloric, hydrofluoric, and hydrocyanic acids, and carbon monoxide. Considerable space is devoted t o the toxic organic gases and solvents,-methane, gasoline, naphtha, benzine, acetylene, benzene, a n d the aromatic and aliphatic hydrocarbons and halogcnated solvents, methyl alcohol, the glycols, alcohols, csters (among them the phthalates), ethers, and ketones. The phenols, hydroxybenzcnes, aniline, nitrobenzene, and the diamines are discussed. A section devoted to the chemical warfare agents, giving their composition, toxic actions, and effective coiicentrations with descriptions of methods for their qualitative detection a n d quantitative determination, is very timely.
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