Mr. Graham's Account of the Formation qfAlcoates. 267 



occasionally a period somewhat longer is required, although 

 it rarely exceeds a week. In winter the alcohol generally re- 

 quires to be exposed to the lime for a day or two longer than 

 in summer. The following rate of concentration was observed 

 in one case in winter, the quantity of alcohol and other cir- 

 cumstances being the same as in the former experiment : 



0-825 



0*817 



0-809 



0-804 



0*799 



0-797 



0-796 

 Quicklime, as a porous substance, appears to be capable of 

 condensing a small portion of alcohol- vapour. It is therefore 

 improper to use it in great excess. In one case, in which 

 three pounds of quicklime were employed with four ounces of 

 alcohol, about one-sixth of the alcohol was lost from this ab- 

 sorption. The quicklime should never exceed three times the 

 weight of the alcohol, otherwise the quantity of alcohol ab- 

 sorbed becomes sensible. It should be spread over as great 

 a surface within the receiver as possible. 



In Richter's process it is improper to operate upon more 

 than a few ounces of alcohol at a time ; as when a large quan- 

 tity of materials is introduced into the retort, the heat neces- 

 sary to disengage the alcohol in the centre of the mass inevi- 

 tably expels the water left in the chloride of lime, at the points 

 where it is more exposed to the heat. In the air-pump also, 

 only a few ounces can in general be concentrated at a time. 

 But in a tall receiver, two or three shallow basins of quick- 

 lime can be supported at a little height above each other, each 

 of them containing a small basin of alcohol resting in it. Or 

 the process might be conducted with facility on the large scale, 

 by means of a tight box of any size, furnished with numerous 

 shelves, which might be covered with quicklime in powder, 

 and support a large number of basins of alcohol. The box 

 might be sufficiently exhausted of air by means of a syringe, 

 for it is not necessary that the exhaustion be nearly complete ; 

 and indeed more inconvenience is to be apprehended from a 

 complete than from an imperfect exhaustion. After produ- 

 cing the exhaustion, no further attention would be necessary; 

 and upon opening the box at the expiration of a week or ten 

 days, the alcohol would be found anhydrous. It is evident 

 that absolute alcohol, procured by this process, could be sold 

 at a price but little exceeding its original cost. It would more- 

 over be of much greater value for the purposes for which it is 



2 M 2 employed 



