34 ' On the Mctions of Camphor and Odor ant Bodies. 



VII. 



Inquiries relative to the Experiments of Qt. Prevofl., of Geneva *, on the expanftve Farce of 

 Odoriferous Emanations, and of Cit. Feniuri, of Modena f , upon the Motion of Camphor 

 upon Water. By Dr. J. Carbadori DEL Prato f. 



As 



1.S I have been employed perhaps more than any other philofopher, in obfcrving the 

 curious motions of camphor, and all the other oleaginous fubftances, as well fluid as folid, 

 when caft on the furface of water, and as I flatter myfelf that I have given a true expla- 

 nation § of thefe phenomena, which had in vain been attempted by Romieu, Volta, Drug- 

 natelli, Lichtenberg, and other refpedlable philofophers, I was of opinion that it was 

 proper for me to repeat the experiments of Prevofl and Venturi on this fubje£l:. I have 

 juft done this, and find that thofe of Prevoft do not poflefs that novelty which was at firft 

 imagined ; but on the contrary, the whole, and particularly thofe of Venturi, tend fliil 

 farther to eftablifli the truth of my explanation. 



I have proved 1|, that all the fixed and volatile oils, as well as the refins and concrete 

 volatile oils, for inftance, camphor, move upon water in confequence of the attraiStion 

 which every oil, whether volatile or fixed, has for the furface of the water, by which it is 

 attra£led, and compelled to extend itfelf till the refpe£live attraOiion of a determinate fur- 

 face is faturated ; and that there are oils, or oily fubftances, which have a greater attrac- 

 tion than others for the furface of this liquid. This has been precifely confirmed by the 

 new obfervations of Prevoft and Venturi. 



The fa£ls related by Cit. Prevoft are certainly true, as has been previoufly remarked by 

 Cit. Brongniart, but the confequences which he conceived to refult from them are not 

 equally accurate. 



It is true, as Prevoft has aflTerted, that if fragments of a concrete odoriferous fubftance, 

 for inftance fmall pieces of camphor or particles imbued with an odoriferous liquor, be 

 placed upon a plate, or on a piece of wetted glafs, that is to fay covered with the flighteft 

 film of water, the latter will be immediately feen to retreat from thofe parts where the 

 fubftances have fallen or fettled, as if it were repelled by feme force proceeding from thofe 

 bodies. 



But it is not true that the retreat of the water from the abovementioned fmall bodies is 

 caufed by the atmofphete of odoriferous emanations, which proceed from them with im- 

 petuofuy, and repel whatever they meet with : but the fa£t is, as Venturi has already ob- 



• Annates de Chimie, Vol. XXI. p. 254, 



• t Ibid, Vol. XXI, p. 262. See alfo our Journal, Vol. I. p. 153, and 205. 

 I Tranflated from the Annales de Chimie XXXVII. 33. 

 § Ann, di Chimica e d'Hiftoria natur. di Brugnatelli, torn. v. 



g See my memoir on this fubjeft, in the Opufc. Scelti di Milano. Ann. di Chimie. et Gioni. fifico- 

 znedico di Bi'ugnatelli, and particularly Vol. XVI, of the lall mentioned work. 



' ferved. 



