L 151 J 



XXTII. Observations on the Pruss'ic Add, and the Pro- 

 duction of a Pijrophorus ly the Frussiute if Iron. By 

 D. H. Grindel*. 



Xt is well known that Schcele, when distilling prussiate of 

 iron per se, found that a part of the colouring matter passed 

 over undeconiposed, and was contained, in con)bination 

 with ammonia, in the water that first passed over, and also 

 in union with carbonic acid gas in the void of the receiverf. 

 I had long intended to prosecute this experiment further, 

 and to examine whether it was not possible in this manner, 

 without further medium, to disengage the prussic acid in 

 the gaseous form from prussiate of iron, to combine it with 

 pure potash, and produce prussiate of potash free irom iron. 

 Late observations on the prussic acid in bitter almonds, &c. 

 induced me to pay attention again to this circumstance, 

 and I made the following experiments : 



I. I put a small quantity of Prussian blue of the shops, 

 finely pulverized, into a small glass fitted with a pneumatic 

 tube, and heated the whole over a spirit lamp, after the 

 tube and the glass had been closely united. As soon as a 

 strong smell of bitter almonds was disengaged, I immersed • 

 the tube in mercury, and received the gas in a solution of 

 pure potash. The gas was continually absorbed by the 

 potash; but it at length displaced the fluid, and I ceased to 

 expose the Prussian blue to heat. 



II. The potash impregnated with gas smelt a little of 

 bitter almonds. I then placed it in a sand bath, and suf- 

 fered it to evaporate slowly to one half. Ou cooling I 

 perceived at the bottom of the glass irregular crystals, 

 some of which were foliated, others' tabular, and some 

 seemed to be cubic. These crystals I separated from the 

 fluid. They exercised a complete r«action, like prussiate 

 of potash on sulphate and nitrate of iron, — only that the 

 precipitate was greenish blue, and became of a beautiful 

 blue onlv by the addition of acid after a part of it had been 

 dissolved. 



III. 'I"he liquid separated from the salt was decomposed 

 with a little alcoliol, and there was produced a white tender 

 precipitate, which I again separated by the (liter. The quan- 

 titv, however, was so small that scarcely any trace oJ: it 

 remained ^>\\ the paper. 



* From Neues Allgt/iuines join mil dir Chrmie i;cn Ucriubstadt, Ht'c. 

 '. o'. i. nci. 6. 



t Sclif.it'i Schiiften, vol. ii p. ^/\i. 



K 1 1\'. The 



