in the Black Oxide qf Manganese. tbS 



it, both in this case and in No.iii,, if aided by a slight degree of 

 heat. 



V. I threw down a pure carbonate from a pure muriate of 

 manganese, obtained by Faraday's process. This was dried 

 and partially decomposed by heating in an oven t with diluted 

 ^sulphuric acid, it gave also the smell of chlorine. 



From these experiments, we may legitimately conclude^ first, 

 that Mr. Mac Mullen was correct as to the fact of the emission 

 of chlorine from the native oxide, which Mr. Phillips has called 

 in question, for it is given off by artificial oxides, into which 

 no trace of a muriate could possibly enter. 



Secondly, that Mr. Mac Mullen was wrong in his supposition 

 that the native oxide is, either in whole or in part, a chlorate of 

 manganese ; for the very supposition takes it for granted that 

 this chlorate is decomposed by the sulphuric acid, and hence 

 the origin of the chlorine. But after solution in sulphuric acid, 

 precipitation by the carbonate and heating, if Mr. M. be cor- 

 rect, we have a chlorate still. 



Thirdly, that these facts form no substantial ground for the 

 further supposition that chlorine is a compound body. That it 

 is not a compound, is supported by evidence that cannot be 

 lightly passed over, and it is more safe to leave one point un- 

 explained, than to venture a reason which is contraiy to all 

 the received doctrines of the science. Nothing is more easy 

 than to find two atomic numbers, which, when added together, 

 will make up a third ; but a very wide induction of facts will 

 be necessary to render the supposed combination even probable. 



I thought it possible that, notwithstanding the incompatibility 

 of the sulphuric and muriatic acids, a minute portion of the 

 latter might be present in the sulphuric acid of commerce. — 

 Into a portion of acid, such as I used in the above experiments, 

 I poured a quantity of muriatic, but after the effervescence had 

 ceased, and the acid had been gently heated, I could find no 

 trace of muriatic acid remaining;. . . . 



A prosecution of the mquiry, in regard to the oxides or lead, 

 may throw some light upon an effect, which it is better in its 

 present stage to attribute to the agency of some foreign suh-», 

 stance, contained either in the Oxide or the acid. 

 . Cja>^paih,I^urham,Qtk^ March, l^2Q. . . , 



