CH. IX ] EXTRACTS. 243 



This extraction may also be performed with Soxhlet's 

 apparatus so that after the final weighing in I. it is only 

 necessary to place the inner tube in another apparatus. 

 When nothing more can be extracted by the solvent, the 

 inner tube is again dried in the steam oven and weighed. 



III. Extract the dry residue from II. with cold 

 water. 



Extract (No. III.) contains dextrins and soluble carbo- 

 hydrates not extracted by '85 alcohol. 



The residue from II. is put into a stoppered bottle 

 with a portion of solvent and shaken for some time in a 

 continuous-agitation machine. The liquid is completely 

 decanted off and a fresh portion of solvent having been 

 added the process is repeated. 



The residue is finally filtered off and thoroughly washed, 

 the washings being added to the extract. The residue need 

 not be dried but is ready at once for No. IV. 



[A bottle fixed on to a vertical wheel which is rotated 

 by a band from a laboratory turbine answers very well for 

 this purpose. A rather slow rotation of about 12 15 

 revolutions per minute is the most effective. An appa- 

 ratus for this purpose made to work with Rabe's turbine 

 is sold by Gallenkamp and Co., London. A simple 

 machine for continuous agitation is also made by the 

 Scientific Instrument Company, Cambridge.] 



IV. Extract the residue from III. with 1 p.c. sulphuric 

 acid at 100. 



Extract (No. IV.) contains the products of the action of 

 dilute acid on starch (dextrins and reducing sugars). 



162 



