April 4, 1902.] 



SCIENCE. 



543 



aqueous solutions of acids, salts and bases 

 are conductors of electricity, and that when 

 such solutions are mixed, chemical changes 

 occur in them instantly in most cases. In 

 this connection a number of typical experi- 

 ments of instantaneous precipitations by 

 double decomposition in aqueous solutions 

 were exhibited. Solutions of silver nitrate 

 were treated with solutions of the chlorides 

 of hydrogen, iron, sodium, potassium, etc.; 

 in each case a white precipitate of silver 

 chloride was instantly formed. Solution of 

 copper nitrate in water was treated with 

 hydrogen sulphide and copper sulphide was 

 thrown down at once, etc. 



The lecturer explained that such instanta- 

 neous chemical changes are, however, not at all 

 confined to solutions that conduct electricity. 

 Absolutely dry hydrogen chloride, ammonia, 

 hydrogen sulphide, phosphorus trichloride, 

 arsenic trichloride, antimony trichloride, tin 

 tetrachloride and silicon tetrachloride, as well 

 as the oleates of copper, nickel, iron and 

 manganese, are soluble in hydrocarbons — 

 benzine, for instance — and such solutions are 

 most excellent insulators or non-conductors of 

 electricity. These solutions have much the 

 same outward appearance as conducting aque- 

 ous solutions. It was shown experimentally 

 that when copper oleate solution in benzine 

 is treated with the chlorides of hydrogen, 

 phosphorus, arsenic, antimony, tin, or silicon, 

 in the same solvent, there forms instantly in 

 each case a heavy brown precipitate which is 

 anhydrous cupric chloride. It is obvious that the 

 formation of cupric chloride in these non-con- 

 ducting solutions is perfectly analogous to 

 the precipitation of silver chloride from the 

 aqueous conducting solutions above men- 

 tioned. 



Further instantaneous precipitations in 

 these non-conducting hydrocarbon solutions 

 were demonstrated experimentally, such as 

 the formation of cupric sulphide, ammonium 

 chloride, nickel chloride, cobalt chloride, etc. 

 It was thus conclusively shown that instan- 

 taneous precipitations take place in non-con- 

 ducting as well as in conducting solutions, 

 and that the changes are perfectly alike in 

 character. From this it follows that it cannot 



be claimed that instantaneous chemical action 

 takes place in conducting solutions because 

 they are conductors, or, in the language of the 

 dissociation theory, because they contain 

 free, charged ions. 



Molecular weight determinations of the sul- 

 phates of copper, iron, nickel, cobalt, etc., when 

 dissolved in water, show that these salts are 

 not dissociated; yet these solutions are good 

 conductors of electricity. On the other hand, 

 abnormally low molecular weights are ob- 

 served in some solutions that are nevertheless 

 non-conductors. Again, according to boiling- 

 point determinations, common salt in water 

 would be dissociated more in concentrated 

 than in dilute solutions, which is absurd. 

 It has further been demonstrated that solu- 

 tions of acid sodium tartrate, as well as solu- 

 tions of other acid salts, are far more sour to 

 the taste and more toxic in their action to- 

 ward plants than they ought to be according 

 to the theory of electrolytic dissociation. 

 From this array of facts, which has been pub- 

 lished in a series of articles in the Bulletin of 

 ilie University of Wisconsin and the Journal 

 of Physical Chemistry, Professor Kahlenberg 

 concludes that the theory of electrolytic dis- 

 sociation is untenable. 



At present scientists have no adequate ex- 

 planation as to why certain solids — e. g., 

 metals — conduct electricity, and certain other 

 solids — «. g., wax or glass — do not. It is 

 therefore not surprising that the real reason 

 that some solutions conduct and others do not 

 is yet unkno-svn. A further careful, experi- 

 mental study of solutions in various solvents 

 will no doubt throw light upon this subject. 

 C. K. Leith. 



PHILOSOPHICAL SOCIETY OF WASHIl^fGTON. ' 



The 548th regular meeting was held March 

 1, 1902. 



Under informal communications several 

 speakers described unusual appearances of 

 rainbows, and Mr. Marcus Baker gave a brief 

 statement of the present status of the Car- 

 negie Institution. 



The first regular paper was by Mr. D. L. 

 ITazard, on 'The Secular Variation of the 

 Magnetic Declination in the United States.' 



