by the Evaporation of the Sulphuret of Carbon, ^5^ 



the effects just related. The fact is, that all these attempts 

 have hitherto failed, and the simplest mode of performing the 

 experiment has uniformly yielded the best results. Indeed, I 

 am now inclined to believe, that unless a substance were found 

 which should exert an attraction upon the sulphureous liquor> 

 without being itself evaporable, (as is the case with the sul- 

 phuric acid, in Mr. Leslie's mode of freezing water), I have 

 nearly reached the limit of coW that can be produced in this 

 manner. It may be proper to add, that the presence of sul- 

 phuric acid in this experiment would have no immediate effect, 

 as it exerts no attraction upon the volatilized liquor ; yet by 

 drying the rarefied atmosphere which surrounds the bulb, it 

 might perhaps assist a little in promoting the process of eva- 

 poration. It may also be useful to caution those who may 

 wish to repeat these experiments, against working the pump 

 too rapidly ; for in this case, a degree of heat is produced (in 

 consequence, no doubt, of the condensed air rushing violently 

 through the valve), which is sufficient to inflame the volati- 

 lized liquor mixed with it. This happens most frequently with 

 pumps of large dimensions, and is immediately perceived by 

 the sulphureous fumes which issue from the barrel ; no other 

 consequence ensues, however, except the injury done to the 

 valves, which, at all events, are apt to be acted upon, and 

 more or less deranged, by the repeated contact of the volati^ 

 lized liquor. On this account the receiver used for these 

 experiments should be of the capacity of two or three pints ; 

 for if it be very small, and the vapour very concentrated, thQ 

 valves appear to be proportionally injured. 



