98 °N OILY HIDROGEN. 



Diftilled oil again difcovers characters to which little atten- 

 tion has been given. It is changed into a volatile odorous or 

 eflential oil, doubtlefs by diiTblving a certain quantity of car- 

 bonated hidrogen. The following are fome of its properties : 

 Properties of When heated with water in a retort, part of it comes over 



dialed oil. i n the diftillation. It has a very powerful but difagreeable 

 fmell, with a degree of lightnefs which places it in the rank 

 of volatile oils, becaufe its weight to that of olive-oil is not 

 more than as 91 to 100. It fwims upon alcohol, which dif- 

 folves it with eafe. Laftly, it enters into ebullition as readily 

 as fpirit of turpentine ; and if a lighted taper be brought to 

 the mouth of the matrafs, the vapour of it burns like that of 

 volatile oil. 



I have not particularly examined the acid liquor which ac- 

 companies the diftilled oil : I (hall only infert a fact relative to 

 Scbate of potato its hiftory. If foap be diftilled to the deftruction of its oil, 



remains after the t]]e f al ; ne re f ic ] ue wnicn J fll0u]( J nave expeded to be the 

 diftillation of * . 



foap. carbonate, is found to be the febate of potafh. It is cryltal- 



lizable, and the fulphuric acid inftantly difengages that pene- 

 trating vapour called febacic acid. But to return to the oily 

 hidrogen, which holds in folution the factitious eflPeniiai oil 

 which I have mentioned at the beginning. When the heat 

 fuddenly ftrikes that portion of the oil which is found there, 

 as if in a red hot tube, it pafles from the vapourous flate to 

 that of carbonated hidrogen, in the fame way as happens to 

 ether, alcohol, radical vinegar, eflence of turpentine, &c. 

 when they pals through a red-hot tube. 



I fhall conclude this by an experiment which Rouelle made 

 in his lectures, and which I alfo fhow in mine ; becaufe in ad- 

 dition to the agreeable fpectacle, the explanation of its caufes 

 is perfectly conformable to the theory of inflammations. 



Beautiful ap- Pour half a fpoonful of olive-oil into a fmall melting cruci- 



pearance from ^Ie obfeurely red, or at that degree of heat which (hall have 

 the furfden com- , ..„ J . . r . ° . . . . . , , 



.bullion of oil ; been dilcovered by tome previous experiments. A thick cloud 



of white fmoke will immediately rife which takes fire at its 

 fummit, that is to fay, four or five feet diftant from the cru- 

 cible. If on the contrary, the combuftion of the cloud arifes 

 from the crucible, it is occasioned by the heat being too great. 

 In that cafe we mutt wait a few minutes, and the phenomenon 

 and wax. W »H appear in all its magnificence. A piece of wax will give 



the fame effects, but it feems to me to require more previous 

 preparations than the oil. 



On 



