£60 HISTORY OF PRUSS1ATES. 



Previous to When it is necessary to concentrate the lixivium, cither to. 



fiule^reen'su!. *- ee P **> or tnat lt ma y ta ^ e U P * ess r00 ™> we should previa 

 phat should be ously take care, as Curandeau perceived, to prevent the sim- 

 wsnt the loss of P' e P rus ^ ate from being destroyed. This is readily done by 

 the simple adding green sulphate in small quantities. In this way it 

 pmsaiate. dissolves completely in the lixivium, which first grows red, 

 then becomes again yellow. An excess of sulphate does not 

 alter it, because the potash, which predominates, reduces it 

 to an oxide; and this falls down, without being able to pass 

 to the state of a prussiate. To attain this, it must present 

 itself accompanied by an acid; for the oxide here spoken of 

 is entirely that at a minimum, which has no action on the 

 triple prussiate. 

 Advantage of * nave divided a lixivium into two equal parts: one was 

 Skis. prepared, or converted into a triple salt, by the green sul- 



phate; the other was not. I afterward distilled them: and 

 the first gave no indication of ammonia; the second fur- 

 nished it as usual. It is indispensably necessary therefore, to 

 prepare the lixivia before they are concentrated. Finally, 



The red oxide neither the red oxide, nor its sulphate, as Scheele found, 

 does not unite • ■, , c v i • ^i 1 • ^ 1 • 



with the sim- ls capable or dissolving in the simple prussiate, and giving 



pie prussiate, it the properties ©f the triple. This oxide too, though 



adapted to become the basis of prussian blue, is equally un- 



or decompose able of itself, to decompose the triple prussiate ; it must b§ 



liSe al P one P . rUS " presented to it in solution by an acid. 



Rccapilulation. 



Component Prussic acid is composed of carbon, nitrogen, and 'hidro- 



pftt* of pmsr gen, in proportions of which we are yet ignorant. We can 

 only conjecture, from the great quantity of carbon it leaves 

 in several instances after it is destroyed, that this principle 

 enters into its basis in a very large proportion, compared 

 Nooxi^en. w * tn the others. Neither is there any fact, that indicates 

 oxigen to make a part of it ; and indeed, from the well 

 known affinities of its three elements, added to the circum- 

 stances under which the acid is formed, we can scarcely, 

 think it does. 

 Has few acid The prussic acid in its separate state has very few of the 

 qualities. common qualities of acids. It has not a sour taste; it does 



not 



