of the Acid of Borax. 69 
tion ; and the oily matter, adhering to the inside of the glass, 
increased considerably. 
Exp. li. When the fluid was distilled, the receiver was changed, 
and the fire increased. A considerable quantity of sublimate was 
obtained, pretty white in colour, as was likewise the surface of 
the mass of salt at the bottom of the retort ; but, lower down, it 
was almost of a light ash-grey. After the sublimate ceased to 
arise, I diminished the fire. 
Exp. lii. Upon the mass of the former experiment, I poured 
the fluid obtained by Exp. xlix. and continued a gentle diges- 
tion. I very soon perceived something rising towards the surface, 
and swimming upon it: after some hours, it appeared to be a 
thick wrinkled skin, like fat, or a skin of mould, increasing 
in size, until it covered the whole surface. White spots of sub- 
limate appeared upon it, but it did not sink. It assumed gra- 
dually a fine lemon colour ; and some yellow matter, though 
not in large quantity, ascended the sides of the retort. The 
fluid having been gently distilled, and the receiver changed, I 
placed the retort in an open fire ; on which, more sublimate 
soon appeared ; but, not long after, it all vanished, and the re- 
tort lost its transparency. The mass contained in it began to 
rise, first gently, and then violently, especially in the centre, in 
large frothy bubbles. The distillation was finished, after ob- 
taining one dram of fluid, and when the frothy bubbling had 
ceased. The retort being broken, that part where the bubbling 
had been strongest, was found to be black ; the upper surface 
being covered with a thin greyish matter, under which a solid, 
compact, and almost vitrified substance appeared. Upon this I 
poured water, and dissolved it in the usual manner ; filtered it, 
