CELL-CONTENTS AND CELL-WALLS. 



85 



the residue in water, and test for (a) reducing sugar, (6) 

 cane sugar. 



(D) Examine for reducing sugar, with Fehling's solu- 

 tion. Since some of the sugar may be 

 present in the alcoholic extract, test for 

 sugars some dried material which has 

 been extracted directly with water. 



97. Soxlilet Apparatus. This apparatus 

 (Fig. 22) consists of a dry flask, which should 

 be weighed accurately, a special extracting 

 tube in which is placed a paper thimble con- 

 taining the tissue to be extracted, and a short 

 condenser. The extracting tube consists of a 

 wide upper piece of glass tubing shaped like 

 a test-tube and fused at its closed end to a 

 narrower tube which is cut off at an angle at 

 its lower end. Below the join of these two 

 pieces of tubing, a side tube is fused into the 

 lower piece ; the other end of this side tube is 

 fused into the wider piece. At the base of the 

 wide tube is fused one end of a narrow siphon 

 tube (on the right in Fig. 22), the other end of 

 which is fused to (and passes through) the 

 narrow tube. 



Place the material in the paper thimble ; 

 place this at the bottom of the wide upper 

 part of the extracting tube, as in Fig. 22 ; fix 

 the narrow lower end of the extracting tube 

 through a cork into the flask ; attach the con- 

 denser, connecting its two tubes to tap and 

 sink. Place ether in the flask, which is to be 

 gently heated over a Bunsen. The volatilised 

 ether passes through the side tube and reaches 

 the condenser ; the condensed ether falls in 

 drops 011 the thimble ; when this is covered, 

 the ether passes back into the flask through 

 the siphon tube, and the process is repeated. 

 The apparatus can be left for two or three 

 hours if necessary, without constant attention. 



Fig. 22. Soxhlet Fat 

 Extraction Apparatus. 



98. Extraction of Proteins and 



Enzymes. These substances should be 



extracted from material dried at a low temperature. 



Enzymes are destroyed by drying at 100 C. 



(A) Pulverise the material, and dry it in an oven at a 



