2C5 M.tiirt .v:,l HitJtuiLs of Caiiiphr at the Siirfna sf Wain. 



occafions, the motioiij were infl.intly (lopped when the water vs'as touched with certain bodic?, 

 without its being eafy to guefs the re;ifon. When particles of camphor were fixed to tlic 

 extremity of a very delicate electrical fly, they produced no motion. All thcfe circum- 

 ftances tended to envelop the phenomenon with obfcurity. Other philofopliers in Italy 

 conftantly fupportcd the opinion of Romieu in their publications. Citizen Vcnturi com- 

 municated his notions on tliefe fafts two years ago at one of the public fittings of the 

 .Literary Society of Modena, his country. He was prefent at the fitting of the National 

 Inrtitutc on the 2ift Piuviofe, when a memoir of Citizen Prevoft on the emanations of 

 odorant bodies was read '■. He announced the obfervations he had made ; and in confe- 

 quence of an invitation to tliat purpofe, lie communicated a memoir of which the follow- 

 ing is an abftraifl : 



Pieces of camphor were cut into the form of fmall columns, one inch in length ; a bafe 

 of lead was fixed to each column ; they were then placed upright in very clean faucers, and 

 pure water poured in, to half the lieight of the column. Two or three hours afterwards, 

 an horizontal notch was manifeft in the column of camphor at the furface of the water; 

 in the courfe of twcnty-faur liours, ortliereabouts, by the notch becoming gradually deeper, 

 the column of camphor was cut in two at the middle. The two pieces of the column, 

 neverthelefs, that is to fay, the lower, which was immerfed in the water, and the upper in 

 the air, fullered fcarccly aay perceptible diminution. 



From this experiment, and others made with different pieces of camphor, kept feparately 

 in the air, in the water, and at the furface of the water, the Author deduces that the moll 

 aflive virtue for diffolving camphor refides at that part where both the air and the water 

 couch the camphor at the fame time. Hence he explains, why, in like circumftances, cam- 

 phor evaporates more quickly in a moift than in a dry air; and why the Hollanders ufe water 

 in their procefs for fubliming this fubftance. 



It might be thought that the camphor was decompofed at the. furface of the water; that 

 the water might feize the acidifying part, wliich renders tlie camphor concrete ; and that 

 the volatile part is diffipated in the atmofphere. The Author rejefls this notion. He thinks 

 that water with camphor floating on its furface becomes charged with no more than a very 

 fmall portion: i. Becaufe in thefe circumftances the water acquires the fame tafte and fmell 

 of camphor as it obtains when a fmall quantity of this fubftance is kept plunged in the 

 fame fluid. This water, by e.xpofure to the air, lofes the qualities with which it had been 

 charged, and becomes infipid, and without fmell. 2. Becaufe when the water is faturated 

 with all it can take up, the dilTipation of the camphor continues at its furface as before. 

 3. Becaufe the a<;rial emanations of camphor made at the furface of water, do themfelves 

 cryftallize into camphor. 



Camphor, at the furf.ice of the water, docs nothing, therefore, but diflblvc ; and when 

 diflblved at the ordinary temperature of the atmofphere, it is not at firft in the ftate of va- 

 pour, as has been thought. It is fimply a liquid which extends itfelf over the furface of 

 water itfelf; and by this means coming into contadi with a great furface of air, it is after- 

 wards abforbed and evaporated. This is proved by the following fafts: i. The folution of 

 camphor at the furface of water is more rapid in proportion to the extent of the furface. 



■' Philofophicjl Journal, I. 153. 



2 In 



