ProfeBsor Thomas Thomson on the Oxides of Bismuth. 



According to Neumann, 0*027 



According to Dulong and Petit, 00288 

 According to Regnault, 003084 



Mean, 0*02888 



It was observed by Dulong and Petit that if the atomic weight of a 

 body be multiplied bj its specific heat, the product is a constant 

 quantity. This has been confirmed by the subsequent experiments of 

 Avogadro, of Neumann, and of Regnault, made expressly to put the 

 statement to the test of experiment. I infer from it that every atom 

 is surrounded by the same quantity of heat. The constant quantity 

 obtained by multiplying the specific heats and atomic weights together, 

 is (if we make use of the late experiments of Regnault, which are 

 probably the most accurate,) 4. If therefore, we divide 4 by the 

 atomic weight of bismuth, the quotient must give us the specific heat. 

 Now, dividing 4 by 13*5 we obtain for a quotient 0"0296. This differs 

 from the mean above stated, by 0*008, or less than 1 per cent, and 

 from the determination of Regnault by 0*0012, or only 1^ per cent. 

 Now, if we attend to the difficulties which experiments to determine 

 the specific heat of bodies are liable to, we must feel rather surprised 

 that the agreement is so very near, than that it should amount to so 

 much as 1 per cent. 



I conceive, therefore, that there can be no doubt that 13*5 is the 

 true atomic weight of bismuth, and that yellow oxide of bismuth is a 

 compound of two atoms bismuth, plus three atoms oxygen, and brown 

 oxide of one atom bismuth and three atoms oxygen, or at least of 

 some multiple of these numbers. It would be necessary to determine 

 their specific heats in order to obtain absolute numbers. 



nth November, 1841, — The President in the Chair, 



The following gentlemen were admitted as members of the society: — 

 John Hutton Balfour, M.D., Regius Professor of Botany, Andrew 

 K. Young, M.D., Charles Glassford, Esq., John Cochrane, Esq., 

 Walter G. Blackie, Ph. D., Andrew Anderson, M.D., Archibald 

 Walker, Esq., Matthew Adam, Esq.., William King, Esq. 



The accounts which had been previously audited were presented by 

 the Treasurer and Librarian, exhibiting an expenditure of £64 8s. lid. 

 for books during two years, and a surplus in the hands of the Treas- 

 urer amounting to £75 8s. 5d. 



The society then proceeded to the fortieth annual election of office- 

 bearers.— (See page 2.) 



