CARBOHYDRATES 



recrystallized and identified by the determination of its melting-point 

 and nitrogen content. Garard and Sherman 1 claim that "With the 

 best conditions it is possible to detect 5 mg. of glucose in 10 cc. of 

 solution since a distinct precipitate is formed. If the solution is 

 cooled, i mg. gives a distinct precipitate. If the original solution 

 is neutral and comparatively free from other organic matter this 

 test will show i part of glucose in 10,000 of water or i mg. in a 

 o.oi per cent, solution. At this dilution the precipitate is suffi- 

 ciently copious, so that there is no question about its presence." 



The reaction taking place in the formation of phenylglucosazone is 

 as follows: 



CH 2 OH 

 (CHOH) 3 

 CHOH 



Q 



C 

 \H 



Glucose 



CH 2 OH 



I 

 (CHOH)j 



I- 



c=o 



+ C 6 H 5 NH-NH 2 - 



\ 



H 



Phenylhydrazine 



+ C 6 H 6 NH-NH 2 - 

 I 6 + C 6 H 5 NH 2 



Aniline 



NH 



Ammonia 



CH 2 OH 



(CHOH) 3 



"+ C 6 H 6 NH'NH 2 - 

 CHOH 

 yN-NHC 6 H 6 + H 2 O 



C 

 \H 



Phenylhydrazone 



CH 2 OH 

 (CHOH) 3 

 C=N-NHC 6 H 6 H 



\ 



H 



Glucosazone 



(b) Place 5 c.c. of the sugar solution in a test-tube, add i c.c. of the phenyl- 

 hydrazine-acetate solution furnished by the instructor, 2 and heat on a boiling 

 water-bath for one-half to three-quarters of an hour. Allow the liquid to cool 

 slowly and examine the crystals microscopically (Plate III, opposite p. 22). 



4. Diffusibility of Glucose. Test the diffusibility of glucose solution through 

 animal membrane or parchment paper, making a dialyzer like one of the models 

 shown in Fig. 2. 



A most satisfactory dialyzing bag may be made of collodion as follows: 

 Pour a solution of collodion into a clean dry Erlenmeyer flask or test-tube. 

 While rotating the vessel on its longitudinal axis, gradually pour out the collodion, 

 at the same time being careful that the interior surface of the flask is completely 



1 Garard and Sherman: Jour. Am. Chem. Soc., 40, 955, 1918. 



2 This solution is prepared by mixing one part by volume, in each case, of glacial acetic 

 acid, one part of water and two parts of phenylhydrazine (the base). 



