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AiiT. XXIX. — On the Movements of Camphor- upon Water, 
and of different Alloys of Pokissiiim when in contact ipitk 
Water or Mercury, 
1 HE singular movements of small pieces of camphor when 
floating upon water, have been long ago observed. M. Romieu 
and other Italian authors considered them as electrical pheno- 
mena, while MM. Lichtenberg and Volta, who had seen the 
same effects in the benzoic and succinic acids, ascribed them 
to an emanation from these bodies. Brugnatelli discovered, 
that the bark of aromatic plants, when thrown upon water, 
moved round hke camphor, and Venturi observed an analogous 
motion in the saw-dust of different woods, that had imbibed 
either a fixed or a volatile oil. 
The last of these philosophers investigated this subject with 
much attention, and the result of his inquiries is published in a 
Memoir entitled. Precis de qiielques experiences sur la sec^ 
tion que des cylindres de Camplire eprouvent d la surface de 
Veau, et reflexions sur le mouvement qui accompagnent cette sec- 
tion. In this paper Venturi shews, that the camphor is rapidly 
dissolved at the place where it touches the water and the air ; 
that the camphor thus dissolved spreads over the aqueous sur- 
face, and is rapidly evaporated by its being thus brought into 
contact with a greater quantity of air. He then supposes that 
the jets of dissolution produce, by their mechanical reaction 
against the camphor, motions of rotation, &c. ; and that if the cen- 
tre of percussion of all the jets do not coincide with the centre of 
gravity, a rotatory and a progressive motion will result. As 
the jets are occasioned solely at the circumference of the sec- 
tion of the camphor by the plane of the water, it should circu- 
late round a vertical axis, and small pieces should turn with a 
greater velocity than large ones. 
This interesting subject has received new and important il- 
lustrations, in a very able Memoir on the Alloys of Potassium 
and Sodium, by M. G. S. Serullas, principal druggist to the 
Military Hospital of Metz, an abstract of which is published 
* See Mcmoircs jircsentes a VInstitut, tom i. p. 125. Paris 1805. 
