178 ON THE MANUFACTURE OF PRUSSIATE OF POTASH. 
of the pump. The water in the Wolfe's bottle was found 
to contain considerable cyanide of potassium, carried into 
it by the current of air. The cyanized charcoal resulting 
having been lixiviated and the solution treated with protosul- 
phate of iron, yielded about two and a quarter ounces of crys- 
tallized ferrocyanide of potassium. There did not appear 
to be more than about ten per cent, loss of potash, most of 
that employed, allowing for what was accounted for in the 
cyanide formed, was recovered on evaporation. 
It is probable that the product would have been greater, 
had the operation been continued longer, and with a more 
intense heat. 
Until recently we have had no account of the working of 
this beautiful and scientific process by the manufacturer, 
and, although it presents many advantages over the old 
method, yet the difficulties connected with the construction 
of cylinders of sufficient capacity, so as to stand the heat 
required, and with the working of the somewhat complicated 
apparatus on the large scale, are obviously great. It ap- 
pears, however, by an account presented by M. Pelouze, to 
the Academy of Sciences at Paris, that the patentee referred 
to, after two years occupied in modifying and perfecting 
his apparatus, has actually succeeded in carrying it into large 
and successful operation at New-Castle-on-Tyne, in Eng- 
land. This account appears to be a partial report of a com- 
mittee of the Academy,* and from it we take the following 
particulars of the new method of manufacture, as carried 
on at New Castle. 
According to Pelouze, this process is a French discovery, 
having been first observed by M. Desfosses, of Besancon. 
Some years since, MM. Possoz and Boissiere attempted 
to apply it on the manufacturing scale, and in 1843 they 
♦Notice on the fabrication of Cyanides by means of the nitrogen 
of the air : by MM. Possoz and A. Boissiere. (Note presented'by 
M. Pelouze, commissaires MM. Chevreul, Dumas, Pelouze.) Corapt, 
Rend, de PAcad. des Sciences de Paris. Feb. 1848. 
