I06 On the Existence of a real Acid of Colalf. 



is however true, that muriate of barytes is not rendered 

 turbid by arsenical acid : but arseniate of ammonia forms 

 with a concentrated solution of muriate of barytes as abun- 

 dant a white precipitate as this triple combination, wliich, 

 when the solution of the mixed salts is very much diluted, 

 takes place sparinfjly, and in shininiz; leaves : but the preci- 

 pitate, by the addition of free arsenical acid, again disap- 

 pears. What opinion ought therefore to be formed of this 

 third ground of argument may readily be seen. 



In regard to the fourth, I shall leave it entirely to the 

 judgaient of the reader. I shall however observe, that we 

 may conclude, without much danger of erring, that the 

 four circumstances here adduced by Brugnatelii as proofs 

 of the existence of his coballic acid, are not conclusive. 

 They are not contrary to the principle here established by 

 experience, that the supposed cobaltic acid is a triple com- 

 bination of arsenical acid, ammonia, and cobalt, in which 

 the first acts the most distinguished part. In consequence 

 of the falsity of the expenmcnts from which tliey are de- 

 duced, they throw an unfavourable light on the accuracy of 

 Brugnatelli's process, and give us some clue to guide us, in 

 regard to the opinion which ought to be formed of the other 

 assertions of Brugnatelii, and the phenomena he observed 

 in regard to the cobaltic acid. 



From the experiments, considerations, and deductions, 

 here mentioned, we have the following results : 



I. Cobalt cannot be converted into an acid when treated 

 with ever so much nitric acid, and often repeating the 

 process. 



II. Nor can this be cfTcctcd by means of muriatic acid 

 and nitrous acid, according to the process of Schecle. 



III. The supposed cobaltic acid of Brugnatelii is in all 

 probability nothing else than unmasked arsenical acid, an 

 miion of this with ammonia, and a little oxide of cobalt. 

 At any rate, this union produces the phaenomena which 

 Brucnatelli considered as characteristic of his cobaltic acid. 



IV. Cobalt free from arsenic, or the oxide of it, will not, 

 W treatment with nitric acid and ammonia, produce tht 

 phaenomena exhibited by the cobaltic acid of Jirugnatelli, 

 and which can also be exhibited by our union of arsenical 

 acid with cobalt. 



V. These experiments, and the circumstances attending 

 them, prove how necessary it is to examine every new dis- 

 covery before it is adnsittcd as truth ; unless people wish to 

 V)e deceived, and to be under the necessity of relractinfj 

 ^hat they h3v<» before afiscrtrd. 



