on Tin J'esselsj and glazed Pottery . 31 j 



that, even supposing alloy to be made with one-half lead, 

 no individual can swallow per day l-20lh grain of that 

 metal ; a quantity inappreciable in its effects, since we daily 

 swallow a hundred times more when we eat game, without 

 being incommoded by it. From these facts, and many 

 others, it results, that if vessels of tinned copper occasion 

 illness, they ought rather to be ascribed to the want of tin- 

 ning than to the latter. 



Paragraph III. 

 Of Tinning considered as soluble in alimentary Acids. 



Eight saucepans, each capable of containing twenty 

 ounces of water, were turned with the following aflnys : 

 The 1st, with pure tin. 



2d, with tm having 0"05 of lead. 



3d, - - 0-10 



4th, - - 0-13 



5th, - - 0-t20 



dth, - - 0-25 



7th, - - 0-30 



8th, with equal parts of tin and lead. 

 Tinning with pure lead was impossibk-. 

 Info each of these pans there was put a pound of red 

 wine vinegar, which was boiled till it was half consumed. 

 The vinegar of each pan was poured into a glass vessel, and 

 suffered to remain at rest for twenty-four hours. The vi- 

 negar was then poured off", and the precipitates were well 

 washed: each portion of vinegar was mixed with an equal 

 quantity of distilled water ; equal parts of each were put 

 into the vessels, and three rows were formed of eight vessels 

 each. The vessels of the first and second rows contained 

 vinegar; Jthose of the third, sediments. Ncarlv four ounces 

 of the sulphate of potash v.cre poured into each vessel of 

 the first row, and into those of the second and third row 

 about four ounces of hydro-sulphurated water. In the first 

 row no precipitate was observed, consequently there wa?! 

 no lead : in the vessels of the second row there was ob- 

 served a slight chestnut-coloured sediment, which indicated 

 the existence of tin. The pediments of the third row did 

 not change colour, whence it was concluded that there did 

 not exist in them any metallic substances. The vinegar, 

 then, boiled in the tinned pans did not dissolve lead, but 

 only a very small quantitv of tin. 



The sediments of the third row were, for the most part, 



composed of tartar and sulphate of lime. These two salt^", 



3 in 



