84] Estimation of Sugar 55 



apparatus in fig. 20 (page 32), 4 or 5 inches long, is carefully 

 cleaned and a tightly fitting disc of platinum foil which has 

 been perforated is passed down the wider end to block up the 

 thinner tube. A little good asbestos is carefully torn up, then 

 reduced to a pulp with water, and poured into the tube ; this is 

 pressed down carefully, and then a little more pulp poured in 

 until a felted mass about J inch thick has been formed over 

 the platinum. The tube is then connected with a filter pump 

 and washed successively with dilute sulphuric acid, caustic 

 potash, hot water, alcohol, and finally ether. It is then dried 

 in a steam oven and weighed. When this is ready the estima- 

 tion may be carried out as follows : 



' Thirty c.c. of the copper solution and 30 c.c. of the tartrate 

 solution [paragraph 80] are mixed with 60 c.c. of water in a 

 beaker. The liquid is heated by immersing the beaker in 

 boiling water. Twenty-five c.c. of the sugar solution, which 

 must not contain more than 0^25 glucose, are then heated to 

 boiling and added to the liquid in the beaker, and the beaker 

 is heated in the boiling water for ten minutes longer. 



' The liquid is then quickly filtered through the asbestos 

 filter, using the filter pump, and the cuprous oxide is well 

 washed in the filter with boiling water, then with alcohol, and 

 finally with ether. It is dried in the steam oven and weighed.' l 



The weight of cuprous oxide thus found, multiplied by 

 0-5045, equals the weight of glucose in the solution. 



1 Clowes and Coleman. 



