280 FRUSSIC ACID. 



Experimental Enquiries concerning the hejl Method of preparing 

 Prujfiate of Potajh free from Iron. 



Preparation of Four oz. dried blood were intimately mixt with a folution 

 kaU pure*. *' ^^ potalh (containing one ounce of potalh), then evaporated 

 Low ignition of to dryncfs, ignited to rednefs, till no more flame undulated 

 poteV,'°aliVfo^ at the furface of the ignited mafs. The ignited raafs was 

 lution by water, diffufed through fix ounces of water, and the folution filtered. 

 The filtered fluid was colourlefs, it contained an excefs of 

 alkali, and emitted a flrong odour of bitter almonds. It 

 yielded, on being evaporated as expeditioufly as poflible, a 

 faline mafs, confining of a mixture of pruflSate and fub-car- 

 bonate of potafli. In order to feparate thefe two falts, one 

 drachm of the faline raafs was introduced into a vial con* 

 taining a mixture of half an ounce of highly concentrated 

 The fait was alcohol and half a drachm of acetic acid, of 1,036 fpec. grav. 

 tic acid and alco- O" ^g'*^^'"g ^^^ ^^^^ "^ fenfible eflfervefcence took place, 

 bol. but much pruflic acid was difengaged; a proof the pruflic 



acid was retained with a lefs affinity by the alkali than the 

 carbonic acid. On examining the refidue, which had been 

 treated with acetic acid and alcohol, it was found to contain 

 only a fmall portion of prufliated alkali. 

 Very little pruf- From this experiment we learn, that one part of potafli 

 fe^arable from cannot be converted into prufljate of potafli, by being heated 

 the carbonate by to rednefs with four of blood ; and that the quantity of either 

 thofe agents. ^^.^^ ^^ carbonated alkali, under thefe circumftances, can- 

 not be feparated from the pruflSated potafli by means of 

 acetic acid and alcohol. 

 Lefs orWood In order to learn if a lefs quantity of blood would not be 



was then ufed ^^^q advantageous for the produ6lion of pure pruffiate of 

 in the igmtion. » ^,-,Vii i ri ,r 



potafli, four ounces ot dried blood, and two ot carbonate or 



potafli, were heated to rednefs in a crucible till no more flame 



appeared. On covering the mixture with charcoal powder, 



Gr^at evolution and again heating it, a prodigious evolution of ammonia took 



ofaqaflttoni*. place; a phenomenon I do not venture to explain. The 



mafs, after having been diffufed through water, filtered and 



evaporated, yielded a crop of cryfials, confifiing of prufliate 



and fub-carbonate of polafli, the former predominating con- 



fiderably. 



The fubcarbon- On fubjefting this mixture of falts to the joint action of 



rot^fepafable^^y ^^^^^^ ^^^^ ^"^ alcohol, it was found. impoffible to feparate 



alcohol and the pfuflSate of potafli from the fub-carbonate. 



•ceticacid. Being 



