94 TIMEHRI. 
The cinnabar was placed in an iron capsule in an ” 
_ earthern pot, which had its cover luted, and was then ; 
heated. After this operation the cover was scraped in order 
to detach and unite the globules of mercury which had — ¥ 
risen from the capsule. Artificial quicksilver was thus 
obtained, to which the ancients attributed properties 
different from those of natural quicksilver—I mean that 
found in mines. This was however, an illusion, the mer- 
cury being identical whatever the mode of extra€tion. 
The process employed to extraét mercury by vapori- 
sation, is the same as that described by ALEXANDER 
APHRODISIUS to render sea water drinkable, and this 
process is the origin of the alembic, as I shall soon 
explain. 
Another rudimentary process, the first which has been 
applied to the extraétion of an essential oil, is described 
by DIOSCORIDES and by PLINy. It was that of the distil- 
lation of the extraéts of the pine or fir, which we now-a- 
days term turpentine. These were heated in vessels 
over which was stretched wool which condensed the 
vapour. Then the wool was squeezed so as to express 
the liquified produét, that is to say, the essence of turpen- 
line now called oil of resin or flowers of resin. It was 
not long before this played an important part in the 
.composition of inflammable materials employed in the 
art of war. But in the end, these names appear to have 
meant the more liquid part of the resins as wellas the 
water charged with soluble constituents, which in the 
same way as the whey of milk, floated on these resins 
at the moment of their extraétion, in faét the distilled 
and scented water which was evaporated along with — 
the essence. Between these different materials, which 
