Materials for a History of the Prussiates. 355 



hor comparable to any of those formed by the oxygenated 

 acids. It froths continually, and has something saponaceous 

 in its appearance. A lighted candle brought near the bea& 

 of the retort burns this portion of acid : but the loss is hot 

 confined to this ; the acid which this salt retains more 

 strongly, by the help of the potash which begins to predo- 

 minate, also undergoes by the effects of heat a slow de- 

 struction, which converts it into ammonia and carbonic acid. 

 At whatever period of the ebullition we take the product, we 

 always find carbonate of ammonia in it mixed with a little 

 prussic acid ; and latterly, when the water begins to disap- 

 pear, this carbonate is condensed in spiculae in the neck of 

 the retort. 



If we add more water in order to continue the ebullition, 

 these same products are found in the water of the receiver.; 

 But after four or five successive and similar distillations, we 

 rease to perceive them, although the saline residue still con- 

 tains prussic acid in a sensible degree. 



Tt must then be dissolved with alcohol : part of it is dis* 

 solved, and the other totally resists its action. In the al- 

 coholic liquor we in fact find prussiate of potash, but the 

 saline mass undissolved is nothing else but carbonate of pot- 

 ash. The object of the two following experiments was to 

 remove all doubt as to the destruction of the simple prus- 

 siate by the heat of ebullition alone. 



This prussiate does not disturb the muriate of lime : but 

 that which has undergone a long ebullition precipitates it 

 abundantly in calcareous carbonate. There is a transforma- 

 tion therefore of prussiate into carbonate of potash. 



Two quantities of prussiate, the one altered by a lohV 

 ebullition, and the other entire, were employed to precipi- 

 tate ordinary sulphate of iron. Both gave a blue colour ; but 

 after being revived, the former quantity occupied three times 

 less room than the latter. 



If we make dry simple prussiate red-hotj there exhales 

 carbonate of ammonia accompanied by an oleaginous vapour 

 resembling that of hartshorn. The saline mass when dis- 

 solved, separates charcoal, and it is still carbonate of potash 

 mixed with some indecomposcd prussiate. 



Z 2 INFERENCES, 



