202 On the Prussic and Prussous Acids, 



be asserted, that the long boiling with the hydrdguretted 

 ' sulphuret is a powerful de-oxidating process. But it will be 

 said to me, If it is really true that the prussic acid has been 

 deoxidated by this process, you ought to be able to recom- 

 pose that acid from the solution B by oxidation. This 

 struck me very Vorcibly ; and being anxious to give this 

 last proof of the truth of my deductions, I attempted the 

 recom position of this acid by several oxidating processes 

 for some time without success: 1 had at last, however, the 

 particular satisfaction of succeeding completely by the 

 agency of nascent hyper-oxy muriatic acid. The method 

 I employed was the following : 



A little hyper-oxymuriate of potash was put into the bot- 

 tom of a glass tube. Over this some of the liquid B mixed 

 with a few drops of diluted sulphuric acid was poured. The 

 heat of a candle was then applied to the bottom of the tube ; 

 and as soon as a violent action commenced, the heat was 

 withdrawn : by this process the v prussic acid was repro- 

 duced, and was proved beyond the possibility of a doubt 

 by the formation of blue prussiate of iron, when poured in- 

 to a mixture of green and red sulphate of that metal. Blue 

 prussiate may also be produced at once, by substituting for 

 the diluted sulphuric acid, a solution of green sulphate of 

 iron, with excess of acid. 



Having thus succeeded in proving that the tingeing prin- 

 ciple of the liquid B was sub-oxidized prussic acid, my next 

 object was to obtain that principle in a free state : for we 

 roust recollect that we have hitherto considered it onlv in 

 combination with potash, with which it formed a neutral 

 salt ; this circumstance gave me reason for supposing it an 

 acid, and I therefore determined to attempt its separation 

 by abstracting its base by a stronger acid. The following 

 was the process I employed for the purpose. 



The liquid B was evaporated nearly to dryness, and put 

 into a retort with diluted sulphuric acid ; a receiver was then 

 adapted to it, and about two- thirds of, the liquid distilled 

 over by a gentle heat; what remained in the retort was sul- 

 phate of potash. The receiver contained a colourless liquid, 

 with a faint, sour, disagreeable smell, and a decided acid 

 taste. This liquor I have named, in conformity with the 

 principles of the new nomenclature, prussous acid, and its 

 salts prussileSf of which the liquid B contained one in so- 

 lution, namely the prussite of potash. 



The effects of the prussous acid on the earthy and me- 

 tallic solutions, as far as I have tried them, are noted in the 

 following table. 



Table 



