ON THE MANUFACTURE OF PRUSSIATE OF POTASH. lliJ 
had established at Grenelle, a trial apparatus, of sufficient 
capacity to enable them, in less than a year, to put into the 
market over 15,000 kilogrammes (33,000 lbs.) of prussiate of 
potash. But the dearness of fuel in Paris, and also the 
frequent repairs required by the apparatus they then em- 
ployed, (fire clay cylinders in one piece, of 2i metres (8-Kt.) 
high, the fire being applied directly against the cylinder, 
the walls of which were 6 or 8 centimetres (2 or 3 in.) 
thick,) induced them to seek another locality, more eligibly 
situated, as regards the price of fuel and fire clay. Under 
these circumstances, an opportunity was presented them in 
1544, of establishing their system of manufacture at New- 
Castle-on-Tyne, on account of an English company. One 
of them, M. Possoz, (having first, we presume, entered the 
English patent, before referred to,) devoted two years in ef- 
fecting the various improvements in the construction of the 
apparatus which the new method required, and for the past 
two years, the factory at New-Castle-on-Tyne, which M. 
Dumas has lately visited, has been in successful operation, 
producing daily about 1,000 kilogr. (2,205 lbs.) of prussiate 
of potash, of remarkable purity and beauty. 
M. Possoz has succeeded in rendering the apparatus 
capable of resisting, during many months, the destructive 
action of the potash, and the enormous heat the operation 
requires. 
The apparatus is composed of a vertical cylinder, built of 
large fire bricks, which are made of the proper shape for 
the purpose ; the interior diameter of the cylinder is one- 
half metre, (20 in.) the height which is heated to white 
redness is three metres, (nearly 10 ft.) ; through the wall of 
the cylinder, (one-fourth metre thick,) there are orifices at 
proper distances apart. 
The cylinder being heated to white redness, and filled 
with wood charcoal in fragments, impregnated with thirty 
percent, of carbonate of potassa, a suction pump determines 
a current of heated air, jets of flame. &c., from the air fur- 
