Materials for a History* of the Prussiates. 353 



mains of triple prussiate. The new solution, when distilled, 

 gives simple prussiate, which is known by its taste, and the 

 property of not giving blue with solutions of red oxide. The 

 above are the products which I found after the flux of the 

 triple prussiate of potash. 



INFERENCES. 



The triple prussiate cannot support an elevated tempera- 

 ture without being simplified in its composition. It gets 

 rid of the black oxide, and passes to the state of simple 

 prussiate : but the latter can also be reduced to something 

 more simple, as we shall soon see : it then leaves potash in 

 its place, and the ordinary remains of the prussic acid, 

 which are ammonia and charcoal. A part of this last serves 

 for deoxidating the black oxide, to reduce it to iron, and 

 its oxygen into carbonic acid. 



During these changes a part of the triple and simple prus- 

 siates succeed in subtracting themselves, in proportion, 

 without doubt, as the carbonate makes them into a paste : but 

 it is likely that a long continued high temperature in strong 

 vessels, would at last reduce these prussiates to two binary 

 combinations, which are ammonia and carbonic acid, with 

 potash, iron, and remains of charcoal, which the oxygen of 

 the iron and the humidity was not able to. acidify. 



Simple Prussiate of Potash. — It is obtained by saturating 

 after Scheele's method potash with prussic gas liberated from 

 the prussiates of potash or of mercury ; but it is more expe- 

 ditiously obtained bykeepingthe alcohol over a concentrated 

 lixivium of animal charcoal. It- must be shaken from time 

 to time, and the progress of the solution is ascertained from 

 the alkaline and bitter taste of the alcohol. The lixiviums 

 of charcoal from blood or leather are rarely free from a 

 little hydro- sulphuret, because the sulphate which conta- 

 minates the prussiates produces sulphur in them : some then 

 passes into the alcoholic solution ; but the charcoal also 

 contributes to it, for I prepared lixiviums with charcoal 

 from blood and very pure carbonate of potash, and yet I 

 found hydro- sulphuret, although in a smaller quantity. It 

 must not be forgotten that sulphur has been already found 



Vol.32. No. li>7. Dec. 1 S08, Z in 



