1825.] of Claude-Louis Bert hollet. 15 



is only witliiu these few years that the new views which have 

 been taken of the nature of chlorine and fluorine, the discovery 

 of iodine and cyanogen, the decomposition of the alkaUes, and 

 the electro-chemical theory, having together introduced more 

 enlarged and philosophical ideas of the nature of combustion 

 and of chemical affinity, than were entertained by Lavoisier 

 BerthoUet, and their associates, a corresponding modirication of 

 their nomenclature is become necessary. The recent doctrine 

 of chemical equivalents too renders this reform still more requi- 

 site, and promises to give a degree of mechanical precision to 

 chemical nomenclature, such as the French chemists could not 

 possibly have iriiagined or anticipated. The difficulty now is, to 

 bring the leading chemists of Europe to concur in any one 

 method or set of principles ininlroducing the innovation. Each 

 has his own peculiar ideas on the subject, and for want of some 

 centre of reunion, some mode of having a full discussion of their 

 separate opinions, there is as yet no immediate prospect of even 

 a provisional nomenclature, liowever much its want may be felt 

 to be injurious to the interests of science. 



We now approach a brilliant period in tlie life of BerthoUet, 

 who had not yet however completed his 40th year. In 1787, by 

 his essay on the Composition and Properties of Prussic Acid, 

 he gave a striking proof of the independence of a mind which 

 ever judged freely for itself, and thereby often rose superior to 

 the prejudices of the day. It was, as has been previously 

 noticed, one of the doctrines of the theory of Lavoisier, that 

 oxygen is the acidifying principle, and that no acid exists with- 

 out Its presence. So soon as the leading features of this theory 

 began to be received by chemists as correct, an implicit assent 

 to all its details was given by almost every chemist, save Ber- 

 thoUet. We have already seen that in his memoir on Sulphu- 

 retted Hydrogen Gas, in 1778, he stated it to perform ali the 

 functions of an acid, and now again, in this Essay on the Nature 

 of Prussic Acid, he found himself enabled, after the successful 

 issue of an analysis, attended by no ordinary difficulties, to 

 declare, that prussic acid contains no oxygen. He showed that it 

 nevertheless performs every function of an acid, having affinity 

 for and combining with alkahes, neutralizing them, and forming 

 with them crystallizable compounds, and being again displaced 

 from these combinations by the more powerful acids. The ana- 

 logy to an unbiassed mind was complete ;yetBerthoIlet's opinion, 

 that acids may exist without the presence of oxygen, gained not 

 a single convert. The new theory now found an implicit acquies- 

 cence in its errors, not less unreasonable than the reluctant and 

 tardy assent which had been yielded to its truths. Nay, so 

 undisputed became its authority, even in those points in which 

 each man's own experience should have been his guide, that 



