120 Mr. Dalton on Sulphuric Ether. [Feb. 



alcohol and ether chiefly, in proportions to be investigated here- 

 after. In this state it is usually called unreclijied ether. 



When this last liquid is redistilled by a moderate heat till one 

 half has passed over, the liquid in the receiver is denominated 

 rectified ether. It is usually about 0"75 specific gravity, corre- 

 sponding to the second quality. It still consists of ether and 

 alcohol, but with much less alcohol than before. There is great 

 reason to believe that both the uiirectijied and rcctijied ether, as 

 thus prepared, are destitute of water, except so far as it is an 

 essential element of the two hquids, ether and alcohol in their 

 purest states ; the sulphuric acid being well able to retain all the 

 excess of water of common alcohol in the temperatures employed 

 in the two distillations. 



Ether of the first quality, or that in its purest state is to be 

 obtained from the rectified ether just mentioned. The object is 

 to abstract the alcohol still remaining in th^ rectified ether. 

 This may be done in great part by repeated distillations ; always 

 taking the first produce and setting aside the remainder for other 

 use ; but this method is tedious and expensive. A more ready 

 method is to agitate the rectified ether with about its own bulk 

 of pure water ; after agitation the mixture resolves into two 

 fluids, a heavier and a lighter ; the lighter may be decanted, and 

 will be found about two-thirds of the volume of ether used ; it 

 will have the specific gravity 0'73 nearly, and may be considered 

 as ether of the first quality. But it is demonstrable that it still 

 contains some alcohol, and has besides acquired a portion of 

 water from this process. The water)' stratum below contains 

 the greatest part of the alcohol, and has also taken along with it 

 a portion of ether, as is evident from the smell, which is much 

 the same as that of ether itself. This heavy liquid has the 

 specific gravity of 0-96 or 0'97 usually. If this ether of 0'73 

 specific gravity be again treated with water, it will be reduced 

 nearly to 0-72"specitic gravity ; but it still contains minute por- 

 tions of both alcohol and water, the quantities of which are not 

 easily appreciated. Subsequent distillation would doubtless 

 improve the quality a little ; but for most practical purposes 

 there is reason to believe that no material difference would be 

 found between the above and ether of absolute purity. 



Having obtained ether of the specific gravity (j'72, and alcohol 

 of 0-83 specific gravity, both of which may be considered as very 

 nearly pure or free from water ; mixtures of these two liquids 

 may be made in any proportions, and the resulting specific 

 gravities ascertained ; from which we may be enabled to esti- 

 mate the proportions of the two fluids in any specimen where no 

 water is present. 



This operation, however, is more diflficult than may be 

 imagined. By taking ether and diluting it successively with 

 equal portions of alcohol, the resulting specific gravities may be 



