Cai^fe of the Madons, isfc. of Camphor on IVnUr. lag 



«han of cold water. Camphor upon boiling water fublimes in great abundance with the 

 vapour of the water itfelf. 



3. Camphor, when floating upon water, turns and is diflipated by the contaft of the 

 oxigene, carbone, hydrogene, and azotic gafes. Thefe two lail afforded more rapid move- 

 ments, and a more fpeedy diffipation. They likewife more readily dilTolve carbone, phof- 

 phorus, and fuiphur. 



4. When camphor is burned or heated on a float at the furface of water, if it touch the 

 liquid, it gives a confiderable motion to its fupport; but if it do not touch the water, it remains 

 motionlefs. The motioti is not therefore produced by the fimple emiffion of volatilized 

 particles from the camphor. An aftion likewife takes place on the part of the water. 



5. This aaion appears to me to depend on the principle of the motions of bodies which 

 float at the furface of water, and has been explained with remarkable perfpiculty by Monge. 

 Of two fmall pieces of paper, twifted up and moiftened, the one with the pure water, and the 

 other with water well (\xturated with camphor, the firft attrads and the fecond repels cam- 

 phor on the furface of water, which does not afluaily hold that fubftance in folution. Water 

 confequently has more attraflion for folid camphor, than for the little portion which it has 

 already dilTolvcd to faturation. It mounts along the folid piece, where it forms a curvilinear 

 inclined furface. The fmall portion which is dilTolved and faturated, defcends along this 

 inclined fnrface, and in its defcent it repels backwards, by the laws of mechanics, both the 

 furface itfelf, and the folid particle to which it adheres. This feparation of the diflblved- 

 part accelerates the diffipation of the folid piece, by affording a current of water conflantly 

 renewed. The atmofphere abforbs that part of the camphor which is already diffolved and 

 extended on the furface of the water; the evaporation being perhaps alEfted by a fmall. 

 portion of the water itfelf. 



6. If a drop of oil had no affinity with the furface of the water, it would lodge itfelf 

 in a fmall cavity ; and, though more elevated than the furface itfelf, it would preferve the 

 globular form by its affinity of aggregation. But fince it extends in a film over the water, 

 the drop itfelf, or fome of its principles, muft neceffarily be attrafted in the fame manner as 

 fluids which rife along the fides of veflels. 



7. Air, flrongly impregnated with ether, or very hot exhalations of camphor, exercifes on 

 the fmall floating particles at the furface of the water a repulfion fimilar to that of oil, or of 

 camphor diffolved without heat in the water itfelf. The former are elaftic fluids, and the 

 latter fimple liquids. They mull not be confounded togeher. 



1 have perhaps dwelt too long upon a fubjca which feems rather to be matter of curlofity 

 than immediate utility. But it is always a pleafure to me to embrace an opportunity of 

 exprefling my efteem and attachment to you. 



J. B. VENTURL 



Vol. I — August 175)7. Ec 



IV. AnaljJ,.<t 



