British Association for the Advancement of Science. 119 



Dr. Clark read a paper on the limits within which the equivalent 

 weights of elementary bodies have been ascertained. As the re- 

 sult of various researches, Dr. C. stated the following equivalents : 

 viz. 



Greatest, 1293.89 Mean, 1293.27 



" 200.77 " 200.09 



« 177.20 " 176.31 



" 75.92 " 75.60 



Dr. R. D. Thomson read an essay on the proofs of the existence 

 of free muriatic acid in the stomach during digestion. He offered 

 various reasons for doubting the certainty of the conclusion that 

 muriatic acid thus exists, but that as the experiments which he 

 had instituted in regard to the subject were not completed, he 

 brought them forward at this time chiefly to show the necessity 

 of further investigation. 



Mr. Benson presented a paper on the theory of theform,ation of 

 White Lead, He stated that white lead made from litharge, 

 (protoxide of lead,) was rejected by painters. It is found that 

 prepared in this way it is crystalline and partly transparent, 

 whereas the ordinary white lead is amorphous and opake. It is 

 found that in order to obtain the amorphous carbonate (or white 

 lead) from litharge the latter must be supplied with a very minute 

 portion of acetic acid. 



Prof Schonbein of Basle proposed a 7iew theory of the galvani- 

 zation of metals. The discovery of the chemical power of the 

 voltaic pile, made at the beginning of the present century by 

 British philosophers, drew the attention of the scientific world to 

 the relations between chemical and electrical phenomena. In- 

 deed, only a few years after this important fact had been ascer- 

 tained, Davy and Berzelius did not hesitate to assert the theory, 

 since generally adopted, — viz. that chemical and electrical forces 

 are essentially the same. Prof S. enumerates the results of sev- 

 eral recent experiments which he considers as invalidating this 

 theory. From these results he infers — 1st. That neither common 

 nor voltaic electricity is capable of changing the chemical bear- 

 ings of any body, and that the principles of the electro-chemical 

 theory, as laid down by Davy and Berzelius, are fallacious. 2d. 

 The change which certain metallic bodies, when placed under 

 the influence of a current, seem to undergo with regard to their 

 chemical relations, is due to the production of some substance or 



