of the Acid of Borax . 67 
and like coal. I now poured common concentrated muriatic acid 
upon three grains of it, and digested the mixture, for forty-two 
hours, in a considerable degree of heat, but no dissolution was 
apparent. I then added smoking nitrous acid, and digested it 
for twenty-four hours, till it boiled, without any apparent disso- 
lution. I added some sugar, (about two grains,) but without 
effect, except that its colour grew yellowish. I now boiled the 
fluid, till it all evaporated in reddish-yellow vapours : there re- 
mained a very black, thick, glutinous mass, smelling like burnt 
sugar. Having added three ounces of water, the greatest part of 
the blackish matter rose to the surface, and the water appeared 
only a little tinged. The fluid part, indeed, became brown by 
boiling ; but, after rest and subsidence, it again grew clear. I 
filtered it, a ; then poured two ounces more distilled water upon 
the residuum, and, after digesting, boiling, and filtering, added 
the filtered fluid, b, to the former, a. After this treatment, there 
remained two grains of residuum, c. 
Exp. xxxii. Having caused the fluid a , b, of Exp. xxxi. to 
evaporate, it yielded a salt greyish-yellow mass, which very 
quickly attracted the moisture of the air. Being again dissolved 
in water, and saturated with potash, a considerable quantity of 
whitish earth was precipitated, very much resembling talc. 
Exp. xxxm. The residuum, c , of Exp. xxxi. which, besides 
its insolubility and lightness, had much of the external appear- 
ance of coal, was now thrown upon melted nitre, and it defla- 
grated. I placed a second crucible with melted nitre close to it, 
and having, at the same moment, thrown into one the above- 
mentioned residuum, and into the other a quantity of common 
charcoal pulverized, I could not observe the smallest difference 
in effect. Very little difference was also apparent, as to the 
K 2 
