(J^ METHOD OP RESTORING RANCID ESSENTIAL OILS. 



inventor. I will take an early opportunity of fpeaking more 

 fully refpeding it. In Mr. Howard*s fyphon the funnel part 

 may in fome meafure be confidered as a fubftitute for the fide 

 fudlion pipe. In large fyphons neither will operate unlefs there 

 be a flop cock at the bottom of the outer leg: in fmall inftru- 

 raents, fuch as that in the drawing, the lloppage is made by 

 the finger. 



The principal intention of a periodical journal being to pub- 

 liih in the form of a book fuch eflays as from their concifenefs 

 might neither be ciiculated nor preferved adequately to their 

 merits, it feems to follow that larger works muft for the mod 

 part be exceptionable from the fpace they occupy. The ex- 

 cellent treatife of Profeflbr Playfair being in Englifti, and of 

 confiderable length, has not yet been reprinted in our work, 

 chiefly for the latter reafon; but I will avail myfelf of the obli- 

 ging indications of Mr, Farcy to re-confider both the works 

 he mentions. 



XV. 



Method of refioring rancid EJJential Oils. By J. B. Dt 

 RoovER.* 



Procefs for purl- UuRING my long and frequent experiments on elTential 

 ladlt oils. ' ^^^s* ^ \i^vQ. difcovered a method of refloring them, when 

 rancid, which appears to poflefs great advantages. The ex- 

 periment which led me to it is as follows: — 

 One fixtecnth I mixed one ounce of fulphuric ether with fixteen ounces 

 tothe^.U^'^'^^'* of oil of peppermint flightly rancid; I left this compound in 

 •ndlcftindi- digeftion for twenty -four hours, and then added five pints of 



geftion; fpirits of the fame mint. The folution was complete. I fil- 



Mve pints of al- , , ,. , ,.o-ii i • . i i t 



cohol added. tered the liquor and diltilled it over the water bath, i ex- 



Diftillation on pe(5led that nearly the whole of the oil would have pafled over 



Moft of the oil ^" ^^ diftillation along with the alcohol and the ether ; but, on 



remained be- opening the ftill, I was much furprized to find the greater part 



"* * of the oil fwiraming on the furface of the refidual fluid. To 



afcertain the quantity of oil which had paflTed over, I precipi- 



* From the Joumal of Van Mons (to whom it was communi- 

 cated by the author,) V. 107. No. 13. 



4- tated 



