[CONTRIBUTION FROM THE MASSACHUSETTS INSTITUTE OF TECHNOLOGY. 3
REVIEW OF AMERICAN CHEMICAL RESEARCH. VOL. IV.
No.
11.
ARTHURA. NOYES,Editor ; HENRYP. TALBOT, Associate Editor. REVIEWERS:Analytical Chemistry, H . P. Talbot and W. H. Walker; Biological Chemistry, W. R. Whitney ; Carbohydrates, G. W. Rolfe ; General Chemistry, A. A. Noyes ; Geological and Mineralogical Chemistry, W. 0. Crosby ; Inorganic Chemistry, Henry Fay ; Metallurgical Chemistry and Assaying, H. 0. Hofman ; Organic Chemistry, J. F. Norris ; Physical Chemistry, H. M. Goodwin ; Sanitary Chemistry, E. H. Richards ; Technical Chemistry, A. H. Gill and F. H. Thorp.
GENERAL AND PHYSICAL CHEMISTRY. A . A . N O Y E S , REVIEWER.
The Atomic Weight of Cadmium. BY H. N . MORSEAND H . B . ARBUCKLE.A m . C%?em.J., 20, j36-542.-In order to determine any correction that may exist for the presence of retained gas in the cadmium oxide, the authors have repeated the atomic weight determinations of Morse and Jones ( A m . Chem. I., 14, 241 ) using essentially the same method and the same samples of cadmium. T h e gas evolved on dissolving the oxide was collected a s in the authors' experiments withzinc oxide (this Rev., 4, js), and, a s before, was found to be very appreciable in quantity, and to consist of oxygen and nitrogen. T h e uncorrected result, 112.084, is very close to that previously obtained, I 12.071, while the corrected one, I 12.377, now agrees well with those obtained by Bucher, 112.39 and 112.38, in his work on the chloride and bromide of cadmium. A Table of Atomic Weights. BY THEODORE WILLIAM RICHARDS.A m . Chem. 7., 20,543-j54.-The author has made a critical study of the reliability of the existing atomic weight determinations, and has compiled a new table of atomic weights. I n the case of seven elements his values differ markedly from those of Clarke, a s is shown be lo^ : Richards.
....................... 120.0 ........................ 112.3 ......................... 40.0 .................... 24.36 ...................... '95.2 ........................ 184.4 ........................ 240.0
Antimony Cadmium Calcium Magnesium.. Platinum.. Tungsten Uranium
Clarke.
120.43 11r.gg 40.07 24.28 194.89 184.83 239.59
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Review of Anzericarb Chemical Research.
The Reliability of the Dissociation Values Determined by BY ARTHLR A. Electrical Conductivity Measurements. NOYES. J . Am. Chem. soc., 20, j17-j28.-The author endeavors to show that an error has been made by van Laar (Zfschr. phys. Chenz., 21, 79) in t h e derivation of his heat-ofsolution formula, and t h a t therefore his conclusion based thereon in regard to the unreliability of the dissociation values determined by electrical conductivity is entirely unjustifiable. T h e question is also discussed from several other points of view. Incidentally a new, rigidly exact and general expression is derived from the relation between the heat of solution of dissociated substances and the change in their solubility with the temperature. ilolecular Weights of Some Carbon Compounds; A Few Words More. BY C. I,. SPEYERS.J . Am. Chem. Soc., 20, 546j47.-This note is a reply to the criticisni by the reviewer of a previous article by the same author ( f h i s Rev., 4, j j ) , I n explanation of his presentation to his readers of several pages of numerical results without a word of discussion, the author states that he himself was at a loss to account for the peculiar results obtained. H e rejects the suggestion of the reviewer as to t h e possibility of error from imperfect elasticity of the bulb. The Atomic irass and Derivatives of Selenium. BY VICTOR 20, jjj-j79.-A current of hydrochloric acid gas was passed over silver selenite, first in the cold, then at a general h e a t ; the silver chloride formed mas weighed, and reduced with hydrogen; and the residual silver again weighed. Eleven determinations of the ratio hg,SeO, : aAgC1 gave 79,329 as the atomic weight of selenium and eight determinations of the ratio Ag,SeO, : a A g gave an identical value. From animoniuni bromoselenate the selenium wxs precipitated by hydroxylamine hydrochloride, the precipitate collected on a Gooch filter and weighed. Eight determinations of the ratio (SH,),SeBr, : S e lead to the atomic weight 79.28j. I n conclusion, a large number of organic and inorganic brotnoselenates are described ; and evidence of the non-existence of a seleniuiii monoxide is furnished by several experiments. Osmotic Pressure. BY C . L. SPBYERS.J . Am. Chem. Soc., 20, j7g-j8j.-The author attempts to show with the help of hypotheses relating to the constitution of solutions, that the specific gravity value which enters in the thermodynamical relation between osmotic pressure and vapor pressure is that of the pure solvent and not that of the solution. This conclusion h a d , however, already been reached by other authors. T h e author, to be sure, considers the mechanical arrangement in-
LENHER.J . Am. Chem. Soc.,
AnaZyticaZ Ckemistry .
I21
volved in the demonstration of it recently given by Noyes and Abbot to be “ p u r e l y imaginary and not possible in fact,” and l 1 the results depending on their theoretical deductions to be valueless. ’ ’
ANALYTICAL CHEMISTRY. GLTIMATE ANBLYSIS. W. H. WALKER,REVIEWER.
On the Lindo-Gladding nethod of Determining Potash. BY A. I,. WINTONAND H . J. WHEELER. /. A m . Ckem. SOL.,20, jg7-6og.-With a view of meeting certain criticisms of the I,indo-Gladding method for determining potash, the authors have made an extensive study of the recent work bearing on the subject. Numerous data are presented which show that the objections made to the process are, so far as practical considerations go, without foundation.
On the Estimation of Ilanganese Separated a s Carbonate. BY MARTHAAUSTIN. A m . /. S i . , 15~,382-384.-The separation of manganous carbonate is shown to be both rapid and complete when made in a warm solution and in the presence of considerable ammonium chloride. T h e precipitate cannot, however, be weighed as carbonate, as carbon dioxide escapes before all the moisture has been expelled ; but, by the addition of sulphuric acid and subsequent weighing as anhydrous sulphate (this Rev., 4, 60) an accurate determination can be made. A New Volumetric Ilethod for the Determination of Copper. BY RICHARDK . MEADE. J . A m . Chenz. SOL., 20, 610-613.-A volumetric method for the determination of copper more accurate and also more widely applicable than either the cyanide or iodine method is found to be the following : T h e copper is precipitated from an acid solution by addition of ammonium or potassium thiocyanate, and the cuprous salt thus obtained converted to cuprous oxide by warming with potassium hydrate. T o this is added a solution of ferric chloride or sulphate, and the ferrous salt formed by the oxidation of the cuprous oxide is then titrated with standard permanganate solution. A Short Study of nethods for the Estimation of Sulphur in Coal. BY G. I,. HEATH. J . A m . Chem. Soc., 2 0 , 630-637.T h e author makes a comparative study of the five more common methods for the determination of sulphur in coal, and notes such modifications and precautions as he finds necessary to obtaining the most accurate results.
