42* Mr. R. Phillips's Letter to Dr. D. Boswell Reid. 



committed any mistake in his former statement, an excellent 

 opportunity occurred of correcting it here ; but instead of this, 

 he directly refers to and thus confirms it. I will, notwith- 

 standing this positive correction of your erroneous opinion, 

 state another experiment which I have made since I published 

 my Letter, and which confirms that therein related. I put 

 200 grains of crj'stallized nitrate of ammonia into a glass tube 

 about 6^ inches long and | of an inch in diameter; into this 

 I inserted a tube 16 inches long and about l-5th of an inch in 

 diameter. The salt was gradually heated in melting suet; at 

 470° to 480% nitrous oxide was pretty freely evolved, and at 

 48.')° it came over rapidly; when about 40 inches had been 

 received I stopped the process; and I assert that not a particle 

 of nitrate of ammonia was volatilized, — and consequently your 

 opinion on this subject is totally erroneous; and I challenge 

 vou to repeat the experiment and fairly to state the results. 

 You have hitherto made only assertions; I do not believe you 

 have ever used a thermometer in investigating the subject, or 

 it would have been mentioned. 



The next subject which presents itself for consideration, is 

 the nature of the salt which remains after obtaining sulphur- 

 ous acid gas by acting upon 200 grains of mercury with 300 

 grains of sulphuric acid. In p. 15 of the Continuation, you 

 accuse me of "carefully keeping out of view the circum- 

 stance, that the product varies according as they are ' heated 

 together,' or 'boiled to dryness';" and you state that in the for- 

 mer case protosulphate of mercury only is procured, and in 

 the latter bi-persulphate. In my controversy with you, I have 

 always found you much more ready in making a blunder than 

 an experiment, and the present is an instance of this mode of 

 proceeding; or otherwise you would have performed one simi- 

 lar to that which I shall now state. I put 200 grains of mer- 

 cury and 300 grains of sulphuric acid (the proportions which 

 vou recommend,) into a glass tube, and gradually heated it up 

 to nearly 500° in melted suet : when the evolution of sul- 

 phurous acid had ceased, I found that the contents weighed 

 394 grains. Now had the acid and mercury been boiled to 

 dryness, there would have remained an atom of bi-persulphate 

 of mercury weighing 296 grains; consequently the excess, or 

 98 grains, was owing to the presence of sulphuric acid. 



I then treated the mercurial salt with muriatic acid, which 

 left 19 grains of proto-chloride of mercury = about 16 of 

 metal : it is therefore evident, that without heating the mer- 

 cury and the acid to dryness, or beyond the jioint required to 

 procure the sulphurous acid, more than ll-12ths of it were 



converted 



