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be procured, so free from grittiness, as to be capable of 

 levigation, to a sufficient degree of fineness; insomuch, 

 that I was obliged to attempt to make it myself: it may 

 be useful to state, that, by the following easy method, I 

 succeeded in producing some of excellent quality. 



Considering that the vitriol, distilled in close vessels, 

 might probably contract this grittiness, in its calx, from 

 an union of some of its compcjnent parts, or principles, 

 with the water contained in the vitriol, (which is the me- 

 tallic salt of iron,) and that this might prevent its perfect 

 calcination; I thought it best to perform the distillation 

 in the open air, and to begin M'ith exhaling the watei. 

 Accordingly, I commenced Avith slowly roasting the vitriol 

 or copperas, broken into grains as small as shot, by hold- 

 ing it over the fire, on a fire-shovel, till the moisture in 

 it appeared to be dried away. I then put it into a cru- 

 cible, and kept it uncovered, in a clear fire, till it had 

 been some time red hot;* by whicli, the spirit or oil of 

 the vitriol was distilled from it, and the calx or colcothar 

 remained, of a brownish red colour, and of a perfectly 

 equal tfexture, edtirely free from hard or gritty particles: 

 and it was easily levigated, when moistened with water, 



A a 2 on 



* I suppose that the fire ought not to be too high, or too long continued, 

 in this process, Ifest it should convert the calx of the iron into glassy scoria. 

 Experiments will determine tlie due regulation of the heat, so as to ensure 

 success to the operation in every instance. The heat ought to be so great, 

 as to give the colcothar, not a brown, but a red colour. 



