REVIEW OF AMERICAN CHEMICAL RESEARCH. VOL. VII. No. I .
ARTHURA. NOYES,Editor. REVIEWERS: Analytical Chemistry, H . P. Talbot and F. G. Moore ; Biological Chemistry, A. G. Woodman ; Carbohydrates, G. W. Rolfe ; General Chemistry, A . A . Noyes ; Geological and Mineralogical Chem-
istry, W. 0. Crosby and C. H. Warren; Inorganic Chemistry, Henry Fay; Metallurgical Chemistry and Assaying, H. 0. Hofman ; Organic Chemist r y , J. F. Norris ; Physical Chemistry, H. M. Goodwin ; Sanitary Chemistry, E. H. Richards; Industrial Chemistry, A. H. Gill aod F. H. Thorp.
GENERAL AND PHYSICAL CHEMISTRY. A. A .
N O Y E W , REVIEWER.
The Transition Temperature of Sodic Sulphate, a New Fixed WILLIAM RICHARDS. Point in Thermometry. BY THEODORE Am. J . Sci., 156, 201--208.--The author has accurately determined the melting-point of hydrated sodium sulphate, and finds it to be 32.48' according to the meanmercury thermometer. He strongly recommends the use of this salt for the standardizdon of thermometers, and describes the precautions to be observed. T h e chemically pure commercial salt is recrystallized twice, or better, until its melting-point is constant ; it is then pulverized and partially melted in a wide test-tube over a flame, so as to form a pasty mass ; a little powdered anhydrous sodium sulphate is added, the tube is inserted in a wider glass tube serving as an air-jacket, the whole is placed in a water-bath 0.5O-3.o~ above the melting-point, and the semi-liquid mass, in which the thermometer is placed, is gently stirred. The Use of the Transition Temperatures of Complex SysWILtems as Fixed Points in Thermometry. BY THEODORE LIAM RICHARDSAND JESSE BRIGGS CHURCHILL. PYOC. Am. Acad., 34. 277-280.-1n reply to a note by Meyerhoffer and Saunders, the authors claim priority with respect to the matter stated in the title, and emphasize the advantagesof using, for the purpose mentioned, the melting-point of a single hydrated salt over that of mixtures of salts. They give the approximate melting-points of nine salts, melting between 19.7' and 7 8 O , which have been found suitable for the standardization of thermometers. On the Dissociation of Phosphorus Pentabromide in Solutions in Organic Solvents. BY J . H . KASTLE AND W . A. 6-23
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Reuiew of America?? Chemical Research.
BEATTY. Ani. Chem. J . , 21, 392-3gS.-Carbon disulphide and carbon tetrachloride solutions of phosphorus pentabromide of 0 . 0 2 5 - o . 0 0 1 molar concentration are found to have the saine color as solutions in the same solvents containing a nearly equal number of bromine molecules, thus indicating that the dissociation is nearly complete. T h e additioii of phosphorus tribromide to a carbon disulphide solution of the pentabroniide causes it to become lighter in color.
On an Apparatus for ileasuring Very High Pressures. BY A. DE FOREST PALMER, JR. Am.J . Sci., 156,451-454.-The method consists in determining the change in electrical resistance produced by subjecting a mercury thread contained within a glass capillary tube to the pressure to be measured. With the help of the coefficient of change of resistance with the pressure previously determined by the author ( A m . J . Sci., 154, I ) , the pressure is readily calculated. It is stated that the error does not exceed 0 . I per cent., up to pressures of 2 0 0 0 atmospheres. The Compressibility of Colloids, with Applications to the Jelly Theory of the Ether. BY C. B A R ~ S .Am. 1.S C ~156, .~ 28j-298.-1t is found that the compressibility of liquid colloidal solutions (those of gelatine and albumen in water and of India rubber in ether) is not essentially different from that of the solvents, notwithstanding the great differences in viscosity ; but that the same solutions, when coagulated or solidified, have a very much less compressibility, which, however, could not be measured by the method used owing to the occurrence of the following remarkable phenomeiion : the mercury meniscus, at which the pressure was transmitted to the jelly in a capillary tube, assumed with increasing pressure a conoidal form, and threw off little globules of mercury which were projected with a jerky motion, even for a distance of 2 0 ctn., through the jelly. The author attributes the phenomenon to the temporary breaking down of the thread of solid jelly in the middle of the tube, where it is least supported, and suggests that the inertia of matter and the phenomenon of the electric spark may be due to a similar behavior of the hypothetical ether. On Some Experiments with Endothermic Gases. BY W. G . MIXTER. A m . J . Sci., 157, 323-327.--Acetylene is invariably caused to explode by large sparks or a red-hot platinum wire when the pressure is as high as three atmospheres, while at lower pressure these agents often fail to cause explosion. Small sparks, moreover, do not cause it even at much higher pressures. On the other hand, cyanogen does not explode when heavily sparked at five atmospheres. nor does nitrous or nitric oxide do so at twenty atmospheres. A simple experiment is also described
General and Physica l Chemistry.
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illustrating the spontaneous decomposition of acetylene, and the accompanying evolution of heat : a slow current of the gas is caused to issue from a small tube into a larger one surrounding it, the latter being heated to dull redness by a burner at the place where the small tube ends. The jet is then seen to be filled with a cloud of glowing lampblack. Some Boiling-point Curves. BY C. I,, SPEYERS.Am. J. the assumption that the vapor-presn sure equation'* = holds true for both components of
Sa'. , 159,341-344.-Under
P
T+T
a liquid mixture at all concentrations, the author has calculated t h e boiling-points of mixtures of carbon tetrachloride and benzene, carbon tetrachloride and chloroform, and chloroform and benzene, and compared the results with existing experimental data. The agreement is found to be close for the first two mixtures, but poor for the last one, perhaps owing to experimental errors. Hereto the reviewer would remark that, since two components whose vapor-pressures in the presence of each other are expressed by the above equation, cannot form a constant-boiling mixture, and since constant-boiling mixtures are extremely common where the boiling-points of the pure components do not differ greatly from each other (see this R e v . ) , the equation cannot at best, have more than a very limited applicability. Lecture Experiments Illustrating t h e Electrolytic Dissociation Theory and t h e Laws of t h e Velocity and Equilibrium of Chemical Change. BY A. A. NOYESA N D A. A. BLANCHARD. J. A m . Chem. Soc., 2 2 , 726-7 j2.-Seventeen experiments on the subjects stated in the title are described. Full details are given both for the preliminary preparation and the execution of the experiments, and the principles illustrated are explicitly stated.
On t h e Periodic System a n d t h e Properties of Inorganic Compounds. BY JAMES LOCKE. A m . Chem. 20, 581-592.T h e article is principally devoted to the discussion of the importa n t fact that the relations of the periodic system are only apparent when each element is considered in a particular one of its various states of oxidation. T h e author believes that the discove r y of general principles can only be arrived at by a comparison of the physical properties and chemical reactions of compounds of the various elements in the same state of oxidation, and promises soon to publish the results of such an investigation.
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