ESSAY VI. 



ON ARSENIC AND ITS ACID. 1775. 



SECTION I. 



AFTER I had found, by my experiments on manganese, that 

 the inflammable principle is not only present in arsenic, but 

 that it may really be separated from it, I asked myself, 

 What were the other constituent part or parts of arsenic ? 

 I found that it was an acid. Mr. Macquer has given us 

 some very satisfactory information concerning the properties 

 of this mineral ; but whether any one else has since made any 

 experiments upon it, I know not. 



SECTION II. ANALYSIS OF THE WHITE ARSENIC. 

 FIRST METHOD. 



Put 2 oz. of arsenic, reduced to a fine powder in a 

 glass mortar, into a retort of the same matter ; pour 7 oz. 

 of pure muriatic acid 1 upon it, and lute on a receiver. The 

 mixture is immediately to be made to boil, and kept in this 

 state till the arsenic is dissolved ; then, while the solution is 

 still warm, 3 J oz. of pure nitrous acid 2 are to be added to it, 

 together with the acid which has already gone over into the 



1 The specific gravity of this acid to water is as 10 : 8. If a bottle of 

 water weighs 1 oz., a quantity of muriatic acid occupying the same space 

 will weigh 10 drms. 



- Of the same specific gravity as the muriatic acid above mentioned. 



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