12 HISTORICAL INTRODUCTION. 



and 1 atom hydrogen ; and carburetted hydro- 

 gen of 1 atom carbon and 2 atoms hydrogen. 

 The idea thus conceived was applied to car- 

 bonic oxide, water, ammonia, &c. and numbers 

 representing the atomic weights of oxygen, 

 azote, &c. dedifced from the best analytical ex- 

 periments which chemistry at that time pos- 

 sessed. 



In the third edition of my System of 

 Chemistry, published in 1807, I introduced a 

 short sketch of Mr. Dalton's theory, so far as 

 I understood it.* The same year a paper of 

 mine on oxalic acid was published in the Phi- 

 losophical Transactions, in which I showed that 

 oxalic acid unites in two proportions with stron- 

 tian, forming an oxalate and a binoxalate ; and 

 that supposing the strontian in both salts the 

 same, the oxalic acid in the latter is exactly 

 twice as much as in the former.t About the 

 same time Dr. Wollaston showed, that bicar- 

 bonate of potash contains just twice the quan- 

 tity of carbonic acid that carbonate of potash 

 does ; and that there are three oxalates of potash, 

 viz. oxalate, binoxalate and quadroxalate, the 

 acids in which are to each other as the numbers 



* Vol. III. p. 424. 



f Berard, in a paper on the oxalates, which he published by way of cor- 

 rection of mine, though his results are in general more erroneous than 

 my own, denies the existence of binoxalate of strontian. I have often made 

 the salt, and regularly exhibit it to my students. It differs very much 

 from the oxalate. 



