MILK 



49 



extraction apparatus, on the bottom of which a layer of clean, 

 previously extracted cotton wool has been placed to keep back 

 the paper fibres which would otherwise be carried over with the 

 ether. Generally, Soxhlet's extraction apparatus (Fig. 16) is 

 used, but others, e.g. those of Krayenblihl, Storch, &c., can 

 equally well be employed. 



The extraction apparatus is attached below to a carefully- 

 weighed flask, and then enough pure an- 

 hydrous (distilled over sodium) ether is 

 poured into the tube of the extraction 

 apparatus to reach beyond the level of the 

 syphon. The ether then flows into the flask 

 below through the syphon. A suitable con- 

 denser must be attached to the upper part 

 of the extraction tube. Formerly, a con- 

 denser, such as is seen in Fig. 16, or a 

 spiral condenser was used, but latterly a 

 more convenient shape which is not easily 

 broken, for it is usually made of metal, has 

 become general (see Fig. 17). 



A condensing arrangement which deserves 

 general recognition on account of its sim- 

 plicity and efficiency has been designed by 

 Prof. V. Storch of Copenhagen (see Fig. 18). 



This condenser consists of a small cylinder 

 of nickelled brass, 7 cm. long and 2'7 cm. in 

 section. It is rounded underneath, and on 

 the top is a curved disc, the edge of which 

 projects 1 cm. beyond the cylinder. Inside 

 the condensing cylinder are two tubes for 

 the water, one of which reaches almost to 

 the bottom of the condenser, whilst the 

 other only just passes through the disc. 

 The condenser is hung loosely in the tube 

 of the extraction apparatus so that the projecting edges are 

 closely joined to the open mouth of the tube. All the trouble 

 of fixing the condenser to the extraction apparatus by means 

 of a tightly fitting cork is thus avoided ; the ether condenses 

 on the lower part of the condenser, and there is no loss. 



When the extraction apparatus has been fitted together, the 



E 



100 



- CdT 



FIG. 16. Soxhlet's 

 Extraction Ap- 

 paratus. 



