141J Quantitative Analysis of Oil Cakes 95 



used. The water in the bath is warmed to about 60 9 C, and kept 

 at that temperature by bubbling steam into it. A very conve- 

 nient and substantial steam generator is shown in fig. 38. It is 

 made by fitting a half-gallon oil can with a cork, through which 

 pass two tubes — one, d, to conduct steam to the bath, and the 

 other, e, to act as a sort of safety tube and prevent the water 

 rushing back up d when the boiler is cooled, e should pass 

 right down to within an inch of the bottom of the oil can, 

 and stand out at least six inches above the cork, d should 

 terminate at one end just inside the cork, whilst to the other 

 end a metal T piece should be attached to make the distri- 

 bution of steam more even. 



141. The Operation. — Cut up a sheet of white English 

 filter paper into pieces 5 by 8 inches in size, roll them into a 

 loose roll, and wash them two or three times with ether to 

 extract any traces of fat which they may contain. When dry, 

 fold one of these round a piece of glass tubing of such size that 

 the roll will easily slide into the extractor (see fig. 37). Partially 

 withdraw the glass tube until about an inch of the paper 

 roll projects beyond its end. Fold this projecting part of 

 paper so as completely to block the end of the roll ; then 

 withdraw the tube altogether. A sort of cartridge case will 

 thus be formed into which the powdered cake may be intro- 

 duced. 



Weigh out about 3 grams of finely ground cake on a watch 

 glass, and sweep it with a camel's-hair brush into the cartridge 

 case. 



Place the case in the broad tube of the extractor, and affix 

 the flask f. Pour ether (S.G. 720) on to the cake until it 

 begins to syphon over. Allow it all to run into the flask, then 

 half-fill again. Fix the apparatus on to the condenser. 

 Place the water bath as in the figure, and half-fill it with water 

 at 6o° C. Light the lamp under b, and allow the extraction to 



