12 Professor Berzelius on [July, 



the red compound of sulphuric acid with cyanuret of iron and 

 cobalt becomes green by the addition of water, it seizes the 

 sulphuric acid, and the moment afterwards the cyanuret set at 

 liberty becomes hydrated. The solution of this cyanuret in sul- 

 phuric acid does not give crystals by exposure to the air ; it has 

 a dirty-red colour, and water precipitates hydrated cyanuret. 

 The diluted solution contains cobalt. 



5. Hi/Jroci/anate of Iron and Deutoxide of Copper loses its 

 brown colour when it is mixed with sulphuric acid, and becomes 

 white with a shade of greenish-yellow. It is very little soluble 

 in sulphuric acid; water decomposes this compound, and the 

 hydrocyanate of iron and copper reappears with its original 

 colour, without any copper being dissolved in the diluted acid. 



6. Prussian Blue increases in volume in sulphuric acid, 

 becomes white, and resembles starch. The new compound is 

 insoluble in excess of acid. If the prussian blue of commerce 

 is made use of, the acid becomes brown, or even black, by car- 

 bonizing the foreign substances which it contains. The acidu- 

 lous mass, when dried upon an absorbing brick, leaves a 

 pulverulent white substance, which does not exhibit any appear- 

 ance of crystallization. When mixed in a close vessel with 

 water deprived of air, it is immediately decomposed, and resumes 

 its blue colour, the water combining with the sulphuric acid. 

 This experiment proves that the sulphuric acid combines with 

 the hydrocyanate without converting it into a cyanuret ; for, in 

 this case, the water would have separated white cyanuret of 

 iron, and dissolved sulphate of deutoxide, and would not have 

 separated prussian blue. 



7. Cyanuret of Iron and Silver is also soluble in sulphuric acid, 

 but it is decomposed in part at least. A yellowish substance 

 remains undissolved. The colourless liquid, exposed to air and 

 the sun, does not become black, and deposits small crystalline 

 grains of sulphate of silver. 



8. Cyanuret of Mercury gives with sulphuric acid a mass 

 resembling starch. A slight smell of hydrocyanic acid is per- 

 ceived, and if much sulphuric acid be added, it becomes of a 

 yellowish colour, probably on account of the decomposition of a 

 small portion of hydrocyanic acid. The acid dissolves very 

 little of the new compound ; by the addition of water a small 

 quantity is deposited, which, by adding more, is dissolved. In 

 the same way, the insoluble compound, when treated with water, 

 is dissolved without leaving any residuum. 



It remains for me now to say a few words on the nature of 

 the compounds of sulphuric acid with the cyanurets. They may 

 be considered in two modes, either as sulphates of cyanurets, in 

 which the cyanogen acts as oxygen in the base, or as supersalis 

 with two bases and two acids. My first idea in observing these 

 compounds was, that the cyanurets might be considered as oxy- 

 geaated bodies, either acids or bases, which could combine not 

 nly with each other, but with the mated acid*. We have 



