obtaining the Sesqui-ferrocyanide of Potassium. 385 



I made use of this property with the view of preparing a com- 

 paratively considerable quantity of the last-named salt. To 

 arrive at this end, I put into each of twelve large balloons filled 

 with atmospheric air a piece of pure phosphorus, an inch long,,^^ 

 in such a manner that half of the bulk of the pieces of phospho- 

 rus was immersed in water, whilst the other half was exposed 

 to the action of the ambient air. I left the whole to itself at 

 a temperature of 70° F. for about twelve hours, after which 

 time the atmospheres of the vessels appeared to be so muchkj 

 charged with ozone, that their smell resembled that o^i chlo7\ 

 rine; paste of starch containing some iodide of potassium be- 

 came instantaneously black in them, litmus paper was bleached 

 within a few minutes, &c. 



Things being in this state, the acid was carefully removed 

 from the balloons by rinsing them with distilled water, and 

 then an aqueous solution of the yellow prussiate was poured 

 into one of the vessels. I need not say, that in shaking the 

 solution with the ozonized atmosphere of the balloon, the odo-.^ 

 riferous principle disappeared almost instantaneously. Aftei** 

 the ozone had been entirely taken up, the solution was trans-' 

 ferred to a second balloon and shaken; from thence poured 

 into a third vessel, and so on until ozone acted no further upon^ 

 the liquid, or what comes to the same thing, until the solution" 

 no longer yielded prussian blue with nitrate of peroxide of 

 iron. The solution, on being now suflficiently evaporated, 

 yielded most beautiful crystals of the red cyanide. It is 

 worth while to state here, that under the circumstances men- 

 tioned so much ozone had been developed, that the ozonized 

 air of two balloons was sufficient to transform completely 

 5 grammes of the yellow crystallized salt into the sesqui-cya- 

 nide. The formation of this compound depending upon the 

 elimination of part of the potassium contained in the yellow 

 prussiate, it follows that besides the red cyanide another alka- 

 line substance must be formed. What that compound is, I 

 am not yet prepared to say, but I have reasons which make 

 me inclined to believe that ozone combines with some po- 

 tassium, changing the latter into a peculiar peroxide of that 

 metal soluble in water and able to co-exist with the red cya- 

 nide. Those reasons are, that the solution of the yellow cya- 

 nide, after having been decomposed by ozone, exhibits a much 

 stronger alkaline reaction than the yellow salt does ; and that 

 the said solution, by being acidulated with dilute sulphuric 

 acid, colours deeply the paste of starch containing iodide of 

 potassium. It is a remarkable fact, which I ascertained many 

 years ago, that peroxide of lead or of manganese acts in the 

 same manner upon a solution of the yellow cyanide as ozone 

 Phil, Mag. S. 3. Vol. 27. No. 1 8 1 . New. 1 84.5. 2 C 



