1814.] On the Discovery of the Atomic Theory. 335 



account of double decompositions, and the numerous diagrams of 

 double decompositions which he has given in the first plate of the 

 third volume of his Opuscula, demonstrate irresistibly that he enter- 

 tained tlie same opinions On the subject with Dr. Black. Indeed I 

 believe, when Mr. Higgins wrote, these opinions were universally 

 admitted by chemists as first principles : nor do 1 conceive that he 

 was aware that any thing new could be deduced from liis writings 

 till many years afterwards. The first person who formally opposed 

 himself to the atomic theor}', and whose opinions are incompatible 

 with it, was Berthollet. 



Had Mr. Nash been acquainted with these facts, he would have, 

 I presume, expressed himself on this subject with a little more 

 decorum and modesty than he has thought proper to do. 



6. Mr. Nash's sixth assertion w-ill make it requisite for me to 

 state distinctly how far the generalization of the atomic theory is to 

 be found in Mr. Higgins's book. Now there are four remarkable 

 passages in the work in question, which I considered, when I wrote 

 my note, as referring to the theory of volumes. But upon recon- 

 sidering them, I conceive that they may be applied likewise to the 

 atomic theory ; and indeed there is one of the four that applies to 

 that theory without any ambiguity. It is probable that Mr. Nash 

 alludes to three of these four passages in the pages to which he 

 refers ; but the fourth, which I consider as the most important of 

 all, he has entirely overlooked. Injustice however to Mr. Higgins, I 

 think it requisite to bring forward every thing that can be urged ia 

 favour of his claim. The passages are the following. 1 shall not 

 use Mr. Higgins's words, but give his meaning in the modern lan- 

 guage of chemistry. 



Page 3(J. — I ultimate particle of sulphur and 1 of oxygen con- 

 stitute sulphurous acid ; 1 ultimate particle of sulphur and 2 of 

 oxygen constitute sulphuric acid. 



Page 37. — Water is composed of 1 ultimate particle of oxygen 

 and I ultimate particle of hydrogen. 



Page 81. — Sulphurcted hydrogen is composed of 9 ultimate par- 

 ticles of sulphur and .5 of hydrogen. 



Page 132. — The composition of the compounds of azote and 

 oxygen are as follows : — 



Ultimate Particles. 



Nitrous oxide 1 azote + 1 oxygen 



Nitrous gas 1 + '2 



Red nitrous vapour I +31 



Straw coloured nitrous acid I +• 4 



Nitric acid 1 + 



Now from these passages, which arc all 1 can find in the book 

 relating to the subject in question, Mr. Higgins is entitled to aflirra 

 that he had an idea of the atomic theory when he wrote his book : 

 but he is not entitled to affirm that he tauglii it ; or that any reader, 

 merely from perusing his book, woiiJd have formed an idea of tiic 



