118 Mr. D alt on OH Sulphuric Ether. [Feb. 



at different temperatures, as exhibited in a Torricellian vacuum, 

 also the force of the same when admitted into a limited portion 

 of air. From these experiments, as well as from corresponding 

 ones made with water, alcohol, and other fluids, I was led to 

 adopt the important conclusii/n, that steam acquires the same 

 force in air as in a vacuum, and that it ought to be considered 

 the same independent fluid in both cases. Consequently if p 

 denote the pressure of any given volume of air (1), and^ denote 

 the pressure of steam of a given temperature, such steam being 

 admitted to the air, the volume of both in due time become* 



p 

 v-f 



This theorem is most beautifully illustrated by sulphuric 

 ether. Let a comr*on barometer have a drop of ether let up into 

 the vacuum ; it will instantly depress the mercury several 

 inches, more or less according to the temperature. Suppose it 



-were 10 inches, the barometer being 30 ; then— ^. = 1-5; that 



is, if ether be passed up into air under those circumstances, it 

 will in due time increase the volume of air 50 per cent. 



For six years after this I was occasionally engaged in the fur- 

 ther investigation of the nature and properties of ether, in wliich 

 several additional facts, and some corrections of those antece- 

 dently announced, occurred. The combustion of ether was 

 effected in various ways, as well as its analysis, by heat and by 

 electricity. 



During all this time I procured my ether in small quantities at 

 a time, and of various druggists, as suited my convenience. 

 Once or twice I ascertained the specific gravity of the article to 

 "be at or near 0-75 ; and I never found reason to suspect there 

 •was much dift'erence in the specimens. Occasionally when 

 great part of the ether was evaporated by time and neglect, I 

 found a few drops at the bottom of the phial, which did not 

 possess the properties of ether, but this was too small to be much 

 regarded. In an excursion to Edinburgh and Glasgow in 1807, 

 I exhibited the steam of ether, as above described, to a few 

 persons in those two places ; when at the latter place, Dr. Ure 

 was so good as to supply me with ether, but upon trial it did not 

 present the properties I had usually recognized, which at the 

 time 1 attributed to accidental impurities, acquired in the labo- 

 ratory ; upon this he accompanied me to a druggist, where I 

 was immediately supplied with ether of the requisite purity. I 

 apprehend Dr. lire's ether must have been the sjjiritus (clheris 

 sulpliurki of the Edinburgh college, made by adding two parts 

 alcohol to one of ether; or perhaps ether not rectified. 



In 1808 I published the first part of my New System of Che- 

 mical Philosophy, in which I digested all the knowledge I then 

 had on the force of steam from ether in a tabular form. I had 

 acquired from actual observation the forces iu a range of tern- 



