Mr. de Luc on Hfgrometry. 
extreme drynefs to extreme moijlure , the quantity of water 
thus evaporated would not raife the barometer as much as half 
an inch. 6th, Laftly, in chemical operations on airs, the 
greateft quantity of evaporated water that may be fuppofed in 
them at the common temperature of the atmofphere, even if 
they were at extreme moijlure, is not fo much as -r-J-o- P art °f 
their mafs. Thefe two laft very important propofitions, have 
been demonftrated by M. de Saussure. 
