OlLS.

DlSTILLED UlLS, 103

water muft be added to the fubftance, and "mthat it is to be macerated before diftillation.

The water which comes over with the Oil indiftillation is to be kept for ufc

R E M A R K.

EJJential Oils are prepared from vegetables inthe manner of their diftilled waters ; but with afomewhat lefs proportion of water;— thofe of the•odoriferous kind chiefly from fiowers, or plants ina flowering ftate. See Rofemary, &c. in Mat.Med. The time of maceration varies with the tem-perature of the feafon and texture of the fubftance,from two or three days to a week or longer.

The heat, Lewis fays, fhould be expeditiouflyraifed at firft, and continued in fuch a degree, thatthe Oil may come over freely, — that moft of thefeOils require the water to boil, but that many of thofefrom odoriferous fiowers, as Luvender, Roßmary,&c. rife with an heat confiderably lefs ; and, forthefe fubftahces, he propofes a contrivance, by whichthey are expofed to the yapour of boiling wateronly. See his Mat. Med. and Di/p.

Thefe Oils are feparated from the water whichaccompanies them by means of afunnelj the ftem

H 4 of