August 22, 1902.] 



SCIENCE. 



283 



officers of the American Chemical Society, 

 and under the presidency of Dr. Ira Rem- 

 sen. On July 2 and 3, Vice-president Dr. 

 H. A. Weber, of Ohio State University, 

 presided. 



Of the sixty-nine papers which were an- 

 nounced, fourteen were upon subjects re- 

 lating to industrial chemistry, thirteen 

 were in the domain of physical chemistry, 

 thirteen were devoted to organic, five to 

 inorganic and twelve to analytical chem- 

 istry. Among the papers presented were 

 the following: 



Arsenic Pentachloride: Chas. Baskee- 

 viLLE and H. H. Bennett. Abstract 

 published in the issue of Science for 

 August 8. 



Preparation of Pure Prceseodymiuni Com- 

 pounds: Chas. Baskerville and J. W. 

 Tureentine. Abstract published in the 

 issue of Science for August 8. 



The Deportment of Pure Thorium and Al- 

 lied Elements with Organic Bases: 

 Chas. Baskerville and F. H. Lemly. 



The Chlorids of Ruthenium: Jas. Lewis 



Howe. 



Until a few years ago, the only known 

 chlorid of ruthenium was of the type 

 RuClg, 2R'C1. Claus's tetrachlorid was 

 shown by Joly to be a nitroso-chlorid, of 

 type RuClsNO, 2R'C1. Several years since 

 Antony described a tetrachlorid, RUCI4, 

 2KC1. At the last meeting the author 

 described the cesium and rubidium salts of 

 the types RuCl,, 2R'C1, RuO,Cl„, 2R'C1 

 and RUCI3H2O, 2R'C1. The method of 

 forming this latter, called an 'aquo'-salt, 

 was not then known. It has now been 

 found that the salts of this 'aquo' series 

 are formed by boiling the salts of the type 

 RuClg, R'Cl, with alcohol and dilute HCl. 

 These are dehydrated at 180°-200°, giving 

 salts of an isomeric RuCl,., 2R'C1, differing 

 greatly from the ordinary RuCl,, 2R'C1 in 



properties. They become hydrated again 

 on treatment with water. The ' aquo ' salt, 

 on addition of chlorin, gives the tetra- 

 chlorid. RuCl^, 2KC1 is a black ^alt with 

 greenish tint, very soluble and instantly 

 decomposed by water, differing entirely 

 from the salt described by Antony. Using 

 Antony's method, no salt higher than the 

 trichlorid could be obtained, but a hydrated 

 salt, RUCI3, 2KC1, H2O, differing from the 

 'aquo' salt was found. This is probably 

 identical with that described by Miolati. 



By the action of stannous chlorid on 

 ruthenium trichlorid beautiful red isomet- 

 ric oetahedra were obtained, which con- 

 tained ruthenium, tin, chlorin and an alkali, 

 and in which the ratio of ruthenium to tin 

 is 1 : 12. 



An Explanation of Valence and Stereo- 

 chemistry: TheodoeeW. Richards. 

 Attention was called to the fact that the 

 valence of an element is probably connected 

 with its compressibility, since in general 

 the greater the compressibility, the less is 

 the valence. It was shown that this rela- 

 tionship is easily explained with the help of 

 the hypothesis assuming that atoms are 

 compressible and elastic throughout their 

 whole substance (Richards, Proc. Am. 

 4ca(i., 37,1, 1901 ; 399, 1902 ; Zeitschr. Phys. 

 Chem., 40, 169, 597, 1902). The carbon 

 atom, with small atomic volume and com- 

 pressibility would naturally possess high 

 valence, and four lai'ger atoms on combin- 

 ing with it would distort it into the tetra- 

 hedron demanded by the theory of van't 

 Hoff and Le Bel. The disposition of the 

 four added atoms on the faces instead of 

 the poinis of the tetrahedron thus formed 

 would of course make no difference in the 

 geometric relation. If the four added 

 atoms were all different, they would cause 

 an asymmetric distortion of the carbon 

 atom. The electrical relations of valence 

 were purposely omitted from the discussion. 



