132 Renew of Dr. Thomson 



attempts here — a felicity, however, which he had not the courage 

 to claim a very few years ago. In his long paper on the specific 

 gravity of the gases, published in the 16th volume of the Annals 

 {Sept. 1S20), he says, " When 100 volumes of air are mixed with 

 42 or 44. volumes of hydrogen gas, and an electric spark passed 

 through the mixture, the diminution of bulk always amounts 

 to 63 volumes.*" His "hydrogen was then prepared from 

 pure re-distilled zinc, pure water, and pure sulphuric. acid, with 

 the requisite precautions." Mark his language now : — " A mix- 

 ture of 100 volumes of air, and 42 volumes of this pure hydrogen 

 gas, was fired by an electric spark. The diminution of bulk in 

 three successive experiments was precisely 60 volumes.! " 



What confidence can be reposed in such plastic results ? 



He tries to analyze nitre, by igniting it in contact with iron 

 filings contained in a copper tube. Here " chaos is come again," 

 but we shall keep it, if possible, out of our pages. 



He favours us in this chapter with a brief table of liquid nitric 

 acid, which seems to be taken, without acknowledgment, from a 

 copious table published seven years ago in the 8th number of this 

 Journal. 



Taeles of Nitric Acid. 



Dr. Thomas's Attempt, 1825. 



Specific Gravity. [AcidinlOO. 



A table of the atomical relationships of acid and water, at dif- 

 ferent densities, is given at p. 24 of our Journal of January, 

 1819, from which Dr. Thomson's atomical table does not differ; 

 yet he never alludes to these researches which so long preceded, 

 iind in fact superseded, his own. That nitric acid of specific 

 gravity 1.55, consists of 1 atom of real acid -f 1 atom of water, was 

 stated in a well-known chemical publication several years before 

 Br. Thomson's Attempt appeared, iiis table descends no lower than 

 to 1.2012; and it obviously ranges itself as evenly by its pre- 

 decessor, as decency would permit. We are certain that the 

 differences, however small, will do no credit to Dr. Thomson's 

 ocharacter as a chemist. 



* Page 163. f Alien f, i. 90 



