310 PHILOSOPHICAL TRANSACTIONS. fANNO I766. 



dium 55*. This experiment was tried once before. The result agreed prett\' 

 nearly with this ; but, as it was not tried so carefully, the result is not set down. 

 It hence appears, that the fixed air contained in marble, consists of substances 

 of different natures, part of it being more soluble in water than the rest : it ap- 

 pears too that water, when the thermometer is about 55°, will absorb rather 

 more than an equal bulk of the more soluble part of this air. It appears, from 

 an experiment which will be mentioned hereafter, that water absorbs more fixed 

 air in cold weather than in warm ; and, from the following experiment, it ap- 

 pears, that water heated to the boiling point is so far from absorbing air, that it 

 parts with what it has already absorbed. 



Exper. 4. — Some water, which had absorbed a good deal of fixed air, and 

 which made a considerable precipitate with lime water, was put into a phial, and 

 kept about -^ of an hour in boiling water. It was found when cold not to make 

 any precipitate, or to become in the least cloudy on mixing it with lime water. 

 A Exper. 5. — Water also parts with the fixed air, which it has absorbed, by be- 

 ing exposed to the open air. Some of the same parcel of water that was used 

 for the last experiment, being exposed to the air in a saucer for a few days, was 

 found at the end of that time to make no clouds with lime water. 



Exper. 6. — In like manner it was tried how much of the same sort of fixed 

 air was absorbed by spirits of wine. The result is as follows. 



Bulk of air introduced = 1. 



Spirit let up each Air absorbed Whole bulk of Whole bulk of Bulk of air re- 



-j. time. each time. spirit let up. air absorbed. maining. 



^ .207 453 207 453 .547 



J .140 274 353 727 273 



,, .074 103 427 830 170 



.046 030 473 860..., 140 



The mean height of the thermometer, during the trial of the experiment, 

 was 46°. Therefore spirit of wine, at the heat of 46°, absorbs near 2^ times its 

 bulk of the more soluble part of this air. 



Exper. 7. — After the same manner it was tried how much fixed air is absorbed 

 by oil. Some olive oil, equal in bulk to ^ part of the fixed air in the cylindrical 

 glass, was let up. It absorbed rather more than an equal bulk of air ; the ther- 

 mometer being between 40 and 50. The experiment was not carried any further. 

 The oil was found to absorb the air very slowly. 



Exper. 8.— The specific gravity of fixed air was tried by means of a bladder, 

 in the same manner which was made use of for finding the specific gravity of in- 

 flammable air ; except that the air, instead of being caught in an inverted bottle 

 of water, and thence transferred into the bladder, was thrown into the bladder 

 immediately from the bottle which contained the marble and spirit of salt, by 



