256 HISTORY OF PRXJSSIATES. 



proaches nearer to vegetable charcoal: nitric acid, however, 

 cannot inflame it. As azote is capable of forming solid 

 Would it make combinations able to resist a high temperature, what would 

 B,.p . ; | 3e t j ie j n fl aence f animal charcoal in the formation of 



steel? Workmen employ sheep's hoofs for casehardening; 

 has their charcoal any advantage over that of wood ? 

 Prussiate of Equal parts of washed charcoal of blood and potash de- 



fordecTbvit carbonated by lime, or lapis infernalis, afforded me by dis- 

 tillation simple prussiate of ammonia, and a great deal 

 of gas, which had the prussic smell, and burnt with a red 

 flame. 



Equal parts of the same charcoal and oxide of manga- 

 nese afforded me carbonate and prussiate of ammonia. 

 But it does not The, desire of fabricating ammonia with advantage led 



answer for me to the following experiment. I distilled a mixture of 

 maKing sal ~ ■ l 



ammoniac. six drachms of charcoal of blood, two drachms of clay, and 



two Of muriate of soda ; but the product of sal ammoniac 



was less than I had expected. 

 Prus dates from All vegetable charcoals azotized are fit for making prus- 

 cl}ar e coa^ eU ° s * an blue. Thus those of gluten, chieh pease, indigo, and 

 • pitcoal, afforded me tinging lixivia, sometimes mingled with 



hidrosulphuret : those of sugar and sugar of -milk, did not 



give the slightest indication of blue. 

 Charcoals of The charcoals of tic chesnut tree and heath, which 

 and heath^o ST *iiths prefer,, because they have the property of not burn- 

 not contain ni- ing any longer thau they are blown, do not derive this from 

 tK)gen ' azote,' for their lixivia contain no prussic acid. 



Cream of tar- Cream of tartar heated red hot affords a lixivium, which 



tar and sal am- Joes not afford the least indication of it: two parts of cream 



mnniac in cer- . pi • i ' V 



..tain propor- °* tartar and one ot sal ammoniac, the same: but one part 



tions afford a G f sal ammoniac, with four of cream of tartar, yields a lixi- 

 vium, that contains simple prussiate, and affords blue with 

 the green sulphate of iron of the shops. Cream of tartar 

 and nitrate of soda afford nothing, 



; This proves, that animal charcoal is preferable to vegeta- 

 ble on account of the azote merely. It also follows, that, if 

 we should sometime or other discover an azotized compound 

 more capable of sustaining a strong heat than the ammonia- 

 tal salts, we might be able to form prussic acid, perhaps, in a 

 less laborious manner than by means of animal charcoal^ 



Examination 



