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XXVIII. Account of the Airs extracted from different 
Kinds of Waters ; with 'thoughts on the Salubrity of 
Air at different Places . In a Letter from the Abbe 
Fontana, Dir eel or of the Cabinet of Natural Hiflory be- 
longing to his Royal Highnefs the Grand Duke of T uf- 
cany, to Jofeph Prieftley, LL.D. F. R. S. 
Read April 16, 1779* 
I T AKE the liberty of fending you an account of fome 
experiments which I made at Paris in the years 1777 
and 1778 on the air extracted from various kinds of 
waters : fome of the principal of which I thought pro- 
per to tranferibe, that you might make ufe of them if 
you think that they are at all ufeful, and likewife lay 
them before the Royal Society. 
I have extracted the air from the water of a well by 
means of common fire. The water was then made to 
boil in a large, mattrafs of tin, which had a long tube of 
the fame metal, which being bent into two different di- 
rections was with its extremity immerged in a tub of 
cold water. The mattrafs and its tube were intirely 
filled 
