J 



S On air produced by the 



time (though not, I found, in the courfe of a day) have 

 been abforbed by the water, now free from air, I pro- 

 cured glafs veflels of a conical form, terminating in nar- 

 row tubes, into which the air diflodged from the ice 

 might afcend, and not be fubje£t to be abforbed. I was 

 fo fortunate as to have feveral of fuch veflels, and they 

 completely anfwered my purpofe for five or fix procefl'es. 

 Thefe veflels were firft filled with mercury, and then 1 

 introduced into them a quantity of water freed from air 

 by previous freezing ; and when, after expofure to frofl, 

 the ice was melted, the air diflodged from the ice afcend- 

 ed into the nan-ow tubes, and remained without any 

 fenfible diminution of bulk feveral days ; and every time 

 that the water was expofed to the froft, an addition was 

 made to it. At length, however, though the veflels were 

 very Itrong, and contained much mercury, which by its 

 tendency to defcend would give the water room to ex- 

 pand with the lefs danger of breaking the veflel, none of 

 them ferved for more than the number of procefles above- 

 mentioned. 



After the breaking of my glafs vefl"els, I got other cy- 

 lindrical ones made of iron, feven or eight inches in 

 height, and near three inches wide at the bottom, the 

 upper orifice clofed with a cork and cement, in the centre 

 of which was a glafs tube, the diameter of which was 

 about a fifth of an inch. And as the glafs tube was in 

 the greateft danger of breaking by the freezing of the 

 water, and this had happened feveral times before, not- 

 withft;anding all my care to guard it from the frofl:, I now 

 made ufe of fnow and fait, to freeze the water in the 

 iron vefl'el only, placed in a vefl'el of mercury, having 

 been previoufly filled as the glafs vefl!els had been. 



The water on which I now operated was about three 

 ounces, and it had been made as free as pofllble from air 

 by previous freezing. With this apparatus I repeated 



the 



