Method of ajpjying VeJfeU of Tin, 357 



♦o have to fccure the health of the confumers; and 2. of the fimple and eafy method of afcer- 

 taitiing, at all times, the finenefs of tin, without injuring the veiTels compofed ot that 

 material. 



The members of the bureau of weights and meafures (Legendre of the National Inftitute, 

 Gattey, and Ch. Coquebert) propofed, in confequence, a few months ago, to the minifter of 

 the interior, a plan of experiments to be made jointly with thofe of the Council of Mines 

 (Gillet, Lefevre, and Lelievre) to obtain a folution of thefe two queftions. 



Thefe united commiffions invited the affiftance of Citizens Fourcroy, Vauquelin, and 

 Dillon, and after a great number of delicate experiments made with extreme care, the refult 

 of their united labours was a number of new and interefting fa£ts, which ferved to fix the 

 opinion of the fupreme adminiftration of the republic on thofe points which conftituted the 

 objefts of enquiry. 



It is more efpecially a point of juftice to prefent a fummary of the fails to the Philomathic 

 Society, as feven of the commiflion are among its members. 



Chemical experiments have proved, i. that tin is more eafily difTolved than lead, and be- 

 fore it, in point of time, by the action of wine, and of vinegar ; and, 2. that lead is not percep- 

 tibly oxided in thefe fluids, except at the line of contadt of the air and the liquor ; and con- 

 fequently at an extremely fmall furface : 3. that the ncwefl: and mod: acid wine in the neigh- 

 bourhood of Paris diflblved no more than an inappreciable quantity of lead, after having re- 

 mained eight or ten days in veflels of pewter containing 16 per cent of that metal. 



4. That the efFe6l was nearly the fame with vinegar, no perceptible precipitation having 

 been obtained, when the veflels in which wine or vinegar were fufFered to remain con- 

 tained full 18 per cent of lead. In proportion as the vinegar faturates itfelf with tin, it lets 

 fall a fmall quantity of tartarite of lead; but the quantity of this precipitate is extremely 

 fmall, even when the operation is performed with veflels of a large diameter and extended 

 furfece. 



5. When red wine remains in tin veflels, it lofes its colour, which effect is owing to the 

 fettling of the colouring matter after its conbination with the oxide of tin. This depofitioa 

 does not appear to contain lead. The tafte of bad wine made ufe of in this experiment was 

 neverthelefs improved ; but there is reafort to think that it was rather by the precipitation of 

 the colour, and the faturation of part of the acid of the wine, than by the prefence of lead. 



From thefe feveral experiments, the commiffioners have concluded that the alloy of lead 

 with tin might be admitted in veflels intended to contain wine and vinegar, in the proportion 

 of from 15 to 18 per cent, and that there is no reafon to apprehend any injury to the health of 

 thofe who ufe fuch veflels. 



The fecond part of the enquiry was diredled to afcertain a procefs for eafily determining 

 the finenefs of tin. The hvdroftatic balance has long appeared to afford a moft certain me- 

 thod, though thit inflirument has not been employed for fuch a purpof* in any country. 

 Conje6lural methods were fubfliituted which depend on the afpeit or flexibility of \hs metal. 



Vol.. HI. — November 1799. 3 A or 



