268 jDr. Thomson's Answer to the Review of the [Apkil, 



notliing to say to the contrary. Let my arguments and the 

 experiments of Dr. Henry on the one hand, and the statements 

 of Mr. Brande and the witty observations of the Reviewer on 

 the other, be placed in opposition to each other, and let the che- 

 mical world judge between them. 



13. With respect to my mode of taking the specific gravity of 

 phosphuretted hydrogen gas, the Reviewer obserres : " This 

 confession betrays poverty of invention, and ignorance of the 

 methods previously practised in such cases." — (Review, p. 147.) 

 This observation from an individual, who, so far as is known to 

 the public, never took the specific gravity of a gas in his life, 

 and directed against me, who have determined the specific gra*- 

 vity of more than 20 gases, with a degree of care and accuracy 

 seldom equalled, and never surpassed, had surely been better 

 spared. I aftirm that my method is susceptible of greater accu- 

 racy than that which the Reviewer insinuates that I did not 

 know ; and this I affirm from having repeatedly tried both 

 methods. The less complicated an experiment is, the greater 

 is the chance of accuracy. 



14. In page 149 of the Review, a most indecent attack is 

 made upon a paper of mine printed in Nicholson's Journal, vol. vi. 

 p. 92, " On the Compounds of Sulphur and Oxygen." This 

 paper was printed so carelessly that the meaning in several 

 places is much obscured. The experiments described in it were 

 made with an apparatus by no means well adapted for accuracy; 

 but they were so often repeated, and so carefully, that the errors 

 committed are inconsiderable. In my calculations, I employed 

 Mr. Chenevix's analysis of sulphate of barytes as a datum, which 

 is now known to be inaccurate. When the error thence arising, 

 and which has nothing to do with my experiments, is corrected 

 (and it is in any one's power to make the correction), the expe- 

 riments related in pages 95 and 96 show that sulphurous acid is 

 composed of 



Sulphur 48-17 



Oxygen 51-83 



100-00 



Now the true composition of the acid is now known to be : 



Sulphur 50 



Oxygen , 50 



100 



Will the Reviewer pretend that this result is not near enougl 

 the truth to warrant what I have said in my System ? Let him 

 compare it with the latest analysis of Berzehus, and see whether 

 it will suffer by the comparison. As for the experiments of Davy, 



