218 Dr. Thomson's reply to Berzelius's 



but the remarks which you have attached to it. Had I con- 

 tinued silent after these remarks, it occurred to me that your 

 readers would have supposed me conscious of inaccuracies 

 which I do not believe to exist, and of defects which I had not 

 the spirit to acknowledge. 



With respect to Berzelius's observations on my analysis of 

 sulphate of zinc, it is only necessary to state a few facts to 

 enable the reader to appreciate their justice. I sent a copy 

 of my First Principles to Berzelius, because I had combated 

 many of his opinions in that work, and thought it right that 

 he should have an opportunity of vindicating himself, if he 

 thought himself unjustly treated. He wrote me some months 

 after that he could not credit the experiments of a man voho did 

 not know that zinc cannot he precipitated from its acid solutions 

 in the cold. This letter was obviously intended to hurt my 

 feelings, but it was at the same time so foolish that it only 

 excited a smile. It was impossible that he could believe that 

 one who had been actively engaged in chemical investigations 

 for almost thirty yeai*s, and who had perused every chemical 

 tract of any value that appeared during that long and most 

 momentous period, could be ignorant of one of the most ele- 

 mentary parts of the science. 1 had been engaged for years 

 in teaching practical chemistry; and there was at the time a 

 manuscript treatise on analysis written by me, lying in my la- 

 boratory, which was open to all my practical students, many 

 copies of which had been taken and dispersed through the 

 country. In that book the most minute directions are given 

 how to separate the constituents of minerals ; and oxide of zinc 

 is not forgotten. 



On reading Berzelius's letter, I thought that it might silence 

 his malignity if I published a single analysis of sulphate of 

 zinc. 1 transcribed out of the book where I register my ex- 

 periments, the first accurate analysis of this salt that I had 

 made. This book still exists : and should any person have 

 the least doubts about the fact, it is open to his inspection. 

 As this analysis had been made without any view to publica- 

 tion, but merely for my own private satisfaction, I cannot con- 

 ceive any motive that could induce me to falsify the register, 

 unless my object had been to impose upon myself. The 

 weights which I have given, and the quantities of reagents 

 used, are precisely those which I found in my register. The 

 analysis had been made probably a couple of years before I 

 published it, though I do not recollect precisely how long. 

 As for Berzelius's hypotheses about subcarbonates and super- 

 carbonates, I have nothing to do with them. I had only to 



state 



