1818.] Triple Prussiate of Potash. Ill 



weighs 6*611. The equivalent number for this acid, derived 

 from Mr. Porrett's analysis of the ferrureted chyazate of barytes, 

 is 6-813. 



We see from the preceding analysis that one third part of the 

 weight of the acid consists of iron, while two thirds of its weight 

 consists of carbon, azote, and hydrogen. The smallest number 

 of atoms, which agrees nearly with the preceding proportions of 

 the ingredients, is the following : 



2 atoms carbon = 1*5 41-379 



1 atom azote = 1*75 48-277 



3 atoms hydrogen = 0*375 10-344 



3-625 100-000 



This differs from the constitution of hydrocyanic acid by 

 containing two additional atoms of hydrogen. But I consider 

 the proportion of hydrogen in the salt as the part of the whole 

 which is ascertained with the least precision. I conceive it to 

 be very difficult, if not impossible, to determine the quantity of 

 water of crystallization in a salt which cannot be exposed to a 

 red heat without undergoing incipient decomposition. I think 

 it possible likewise that a slip of cork which was interposed 

 between the glass tube and the copper tube, though extremely 

 small, and though not* apparently altered in its texture by the 

 process, might, as it was always exposed to a temperature 

 rather exceeding 212°, have given out a portion of the water, 

 which had augmented the weight of the muriate of lime. These 

 reasons induce me to suspect that the acid in the triple prussiate 

 is hydrocyanic acid united to iron. 



As to the ferruginous ingredient, it is difficult to form an accu- 

 rate idea of the state of combination in which ' it exists in this 

 acid. We have seen that its weight is to that of the hydro- 

 cyanic acid as one to two. Now an atom of hydrocyanic acid 

 weighs 3-325, and an atom of iron weighs 3 - 5. Of course if the 

 ferrureted chyazic acid were a compound of an atom of hydro- 

 cyanic acid and an atom of iron, the weight of the iron would 

 exceed that of the hydrocyanic acid. If we were to suppose an 

 atom of hydrocyanic acid to be united in the ferrureted chyazic 

 acid with half an atom of iron, then the weight would be as 

 follows : 



Hydrocyanic acid 3*325 



Iron 1*75 



5-075 



a weight which does not accord with the equivalent number for 

 ferrureted chyazic acid, as deduced from the preceding analysis • 

 namely, 6*611. In fact, the weight of the acid indicates a 

 compound of one atom of hydrocyanic acid and one atom of iron. 



