688 



SCIENCE, 



[N. S. Vol. IX. No. 228. 



sX oue centimeter distance. Tliis value seems 

 to be very constant, and tlie Hefner lamp may 

 possibly become a standard of total as well as 

 ■of luminous radiation. 



A. St.C. D. 



NOTES ON INORGANIC CHEMISTRY. 

 Two papers have appeared in the Journal of 

 the American Chemical Society, by Dr. F. P. 

 Venable, on the ' Nature of Valence.' The idea 

 of valence in chemistry has been of gradual 

 growth and has merely been the expression of 

 certain chemical facts. In the case of the 

 carbon compounds and in organic chemistry in 

 the hands of Kekule it has proved of immense 

 service, and without it the wonderful develop- 

 ment of this field in the past three decades 

 would have been impossible. Its application 

 to inorganic chemistry has been hardly as happy, 

 and the original conception of a fixed valence 

 has been abandoned for that of variable valence^ 

 but even this is limited to comparatively simple 

 compounds. As an explanation of the struc- 

 ture of double salts, water of crystallization' 

 metal-ammonia bases and other complex inor. 

 •ganic compounds it is wholly inadequate and 

 possibly a hindrance. While in one form or 

 another the conception of valence has permeated 

 and, one might almost say, dominated chemistry, 

 little or nothing has been known regarding its 

 nature. To be sure, in the last decade or so 

 ■several hypotheses have been offered by van't 

 Hoff, Wislicenus, Victor Meyer, Knorr, Fla- 

 witzky and a few others, attributing valence to 

 electrical phenomena, space relations of the 

 atom, etc., but none of these attempted ex- 

 planations has received any measure of sup- 

 port. The hypothesis which Dr. Venable puts 

 forth is that valence is dependent upon vibratory 

 (or kinetic) equilibrium of the atoms. "The 

 question as to whether the atoms of two ele- 

 ments will unite is decided by aflinity which is 

 in some way connected with the eleotrical con- 

 dition of the atoms. There is no apparent con- 

 nection between this and valence." But the 

 atoms "are endowed with motion, and this 

 motion probably varies in velocity and phases 

 with the different elements." "A molecule, in 

 order to exist, must maintain a certain equilib- 

 rium and harmony between these various mo- 



tions, so that there can be all degrees of equi- 

 librium from the very stable to that which may 

 be upset by the least disturbing influence from 

 without." Variable valence will be, in part 

 at least, dependent upon the temperature, and 

 a " sufiiciently high temperature may prevent 

 any harmony of motion whatever being attained, 

 and hence union may become impossible." 

 Valence would then be dependent upon the 

 possible harmony of motion between the differ- 

 ent atoms. The hypothesis is simple and satis- 

 factorily explains many at least of the facts ; 

 thus, for instance, the zero valence of elements 

 like argon and helium might be due, not to 

 their possessing no chemical affinity (though 

 this may be the case), but to their motion not 

 being capable of harmonizing with that of any 

 other element. The weak point of the hypothe- 

 sis is the difficulty of proving it to be true. It 

 would be necessary to first know the nature of 

 the motion of the atom, a problem yet unsolved. 

 It is possible that the spectroscope could aid, 

 but at present we have no clue as to why some 

 elements, as iron, furnish a complex spectrum, 

 while others, like sodium, give a relatively simple 

 oue. At all events Dr. Venable's idea furnishes a 

 good and simple working hypothesis, and one 

 which may have its practical uses for teachers. 



Attention should be called to the First Sup- 

 plement to Dr. H. Carrington Bolton's Select 

 Bibliography of Chemistry, 1492-1892, which has 

 just been published by the Smithsonian Insti- 

 tution. It includes works omitted in that vol- 

 ume, and brings the literature of chemistry 

 down from 1892 to the close of 1897. Dr. Bol- 

 ton has been fortunate in having the coopera- 

 tion of a number of scholars abroad, who have 

 contributed more than 2,000 titles in Arabic, 

 Finnish, Japanese, Bohemian, Dutch, Portu- 

 guese, Swedish, Danish, Norwegian and Rus- 

 sian, no less than 760 titles in the latter lan- 

 guage being furnished by Professor A. Krupsky, 

 of St. Petersburg. Dr. Bolton's bibliograph- 

 ical work is invaluable to chemists and is car- 

 ried out in a manner which is above criticism. 



Peofessoe F. Emich, of Graz, has been kind 

 enough to send me a paper from his laboratory 

 by F. Dorner, with a chemical investigation of 

 the cement from antique water conduits. The 



