1820.] Mr. Dalton on Sulphuric Elher. 127 



The non-efficiency of water in abstracting ether vapour is 

 further manifested by the following experiment. 



I took a tall graduated cylindric jar, of three inches diameter, 

 into which 20 oz. measures of air were passed over water. 

 Thirty i^rain measures of ether (0'73) were then passed up into 

 the air, through a volume of five inches of water, which was of 

 course diminished a little in its passage, and then spread over 

 the surface of the water to the thickness of -n-e-trth of an inch 

 nearly. The volume of air and vapour varied as under : 



II. M. Oz. 



— _ 20 



— 3 224. 



— 6 24 



— 12 26 



-- 20 27i 



— 26 28-^. 



_ 32 284. 



— 50 28 



2 27 27 



1 Day 23 



1 Week 214. 



Washed io" 



Here it is observable, the vaponr increased for half an hour, 

 and then began to dechne again, but slowly. It increased the 

 volume by 84- oz. = 3,960 grain measures, which is equal to 

 15 gr. in weight by the preceding determination ; but the ether 

 weighed 22 gr. ; so that a loss of one-third of the weight of the 

 ether only was occasioned by the action of so great a surface of 

 water on it for half an hour. 



Force of Ether Vcpour. 



My former experiments on the force of ether having been 

 made with an article not of the highest purity, they ought all to 

 exhibit a force too low for the temperature. Such I find to be 

 the fact ; at least within a range of temperature of easy investi- 

 gation, that is, from 30° to 140°. The difference, however, is 

 but small, and may, without much error, be corrected by deduct- 

 ing 2^ or 3° from the respective temperatures, as given in mj 

 table. (New System of Chemistry, p. 14.) The apparatus to 

 be used, consists of a common barometer tube, one bent into a 

 syphon at one-third of the length from the sealed end, and s 

 tall smaller one bent six or seven inches from the sealed end, 

 and having the other leg 40 inches long. The first of these 

 instruments is best used for atmos[)heric temperatures, having a 

 drop of ether let up into the vacuum. The second, is to have 

 its short leg fi led with mercury, and an inch of the other leg, a 

 drop of ether being at the top of the mercury in the short leg. 



