1820. j Mr. Da/ton on Sulphuric Ether. 119 



perature from 0° to 212°. In my former publication I had 

 concluded that the variiitions in the force of steam from water 

 and ether were the same for the same intervals of temperature ; 

 that is, if the force of steam from water was diminished from 30 

 to 1 J inches of mercury, by a diminution of temperature of oO° ; 

 then that of ether would be diminished from 30 to 15 inches by 

 the same number of degrees, though in a much lower part of the 

 scale; the former being from 212° to 182°, and the latter from 

 98° to 68°. Subsequent experience, however, led me to appre- 

 hend that the above intervals of temperature, though expiessed 

 by equal expansions of mercury, are not in reality equal intervals ; 

 but that equal intervals are rather denoted by the forces of steam 

 being in geometrical progression. Consistent with this view I 

 found tl o"; steam from water and ether would concur, for a Ions: 

 range ot temperature, w ith the diu'erence of i atios only ; that of 

 water being 1-321 for 10° of temperature, whilst that of ether was 

 1-2278. 



In the above work occurs the following observation : " Ether, 

 as manufactured in the large way, appears to be a very homoge- 

 neous liquid. I have purchased it in London. Edinburgh, 

 Glasgow, and Manchester, at very diflerent times, of precisely 

 the same quality in respect to its vapour." This observation, 

 though warranted from my limited experience at the time, I 

 now find not altogether correct ; I am sorry that it has occa- 

 sioned an ingenious experimentalist to be led into a labyrinth of 

 error. 



The bulk of the ether use<l in this country has I find of late 

 years been prepared by one manufacturing house in the neigh- 

 bourhood of London. Three qualities of the article are made 

 according to the different uses intended. The highest quality is 

 only made for particular purposes, and is, therefore, not very 

 commonly met with ; it is about 0-73 specific gravity ; the 

 second quality is that intended for medicine ; it is of 0*75 speci- 

 fic gravity, and is that with which all the country druggists and 

 apothecaries are or ought to be supplied as a standard uniform 

 article ; it is that which 1 have always met with in the shops, and 

 which 1 have taken for genuine ether in my former experiments. 

 The third quality is of the specific gravity 0-78 or 0-79 usually ; 

 of course it is much inferior to the last in purity. But it may be 

 proper to observe, that this is the first state of the other two 

 qualities ; they being produced from this by ulterior processes 

 called rectijualiott. 



It is well known that sulphuric ether is procured by distilling 

 a mixture of sulphuric acid and alcohol. The proportions 

 usually prescribed are equal weights of concentrated acid and 

 alcohol. By due management, a liquid of the specific gravity 

 0"785 or 0-79 is obtained, called ether. It is the ether of the 

 third quaUty, just mentioned, and is in fact a compound of 



