i 



iChemicai Science. 161 



t^rboiiized, it melts and falls through the grate as fluid cast 

 steel, into the chamber beneath, from whence it is taken and cast 

 into ingots. 



From three to four hundred weight of iron Is placed in such 

 a furnace, and there is a loss of about one-third from oxidation, 

 and adhesion to the sides: The operation requires from 

 two to three days, with constant blowing. M. Muhammed de- 

 scribed tlK2 charcoal as being exceedingly hard and heavy, and 

 very unlike our charcoal, but did not know «f what wood it was 

 made. 



5. Process for obtaining jmre Nickel. — The following is a 

 process recommended by Dr. Thomson, for procuring pure 

 nickel : — " I take a quantity of the brittle reddish alloy, well 

 IcnowH in commerce by the nanic of speiss. This alloy is 

 chiefly an arseniuret of nickel, though it probably contains also, 

 occasionally at least, several otlier metals. Upon the speiss 

 reduced to a coarse powder, I pour a quantity of dilute 

 sulphuric acid, pjace the mixture in a Wedgewood evaporating 

 dish upon a sand bath, and add the requisite quantity of nitric 

 acid at intervals, to enable the acid to act upon the speiss. By 

 this process I obtain a deep grass- green liquid,while a consider- 

 able quantity of arsenious acid remains undissolved. The green 

 liquid, carefully decanted off the arsenious acid, is evapo- 

 rated on the sand bath, till it is sufficiently concentrated to yield 

 crystals. It is then set aside in a cool place. A deposit of 

 beautiful crystals of sulphate of nickel is obtained. By con- 

 centrating the liquid still further, more crystals of sulphate of 

 nickel fall, but after a certain time the liquid, though its colour 

 continues still a dark green, refuses to yield any more crystals 

 of sulphate of nickel. By evaporating it to the required con- 

 sistency, and then setting il aside, a very abundant deposit is 

 made of an apple-green salt, which adiiercs very firmly to the 

 evaporating dish. I took this matter at first, from its colour, 

 to be arseniate of nickel ; but I found it, en examination, to 

 be a double salt, consisting of sulphate of nickel and arseniatc 

 of nickel, united together. I endeavoured to got rid of the 



Voj.. VIII. M 



