DETERMINATION OF DEXTROSE 197 
Procedure. Place 30 c.c. of the copper sulphate solution, 30 2.¢. of 
the alkaline tartrate solution and 60 c.c. of water in a beaker and heat to 
boiling. Add 25 c.c. of the solution of the material to be examined, 
which must be so prepared as not to contain more than 0.250 gm. of 
dextrose, and boil for two minutes. Filter immediately through asbes- 
tos without diluting. Wash the precipitate with hot water. Dry, 
ignite and weigh as cupric oxide. To calculate the amount of copper 
and its equivalent in dextrose consult Allihn’s table in any chemical 
hand-book. 
Benedict’s Method for Determination of Dextrose. Twenty-five 
c.c. of Benedict’s special reagent (see Appendix) are measured into a 
porcelain evaporating dish, 25-30 cm. in diameter, 10-12 gms. of 
crystalline sodium carbonate, and a small amount of pumice, are added. 
The solution is boiled vigorously over a free flame and the sugar solution 
is run in until a white precipitate is formed and the blue color is dimin- 
ished. After this the sugar solution is run in a few drops at a time until 
the blue color has entirely disappeared. Water may be added to replace 
that driven off by evaporation. Twenty-five c.c. of the reagent =0.05 
gm. glucose or .053 gm. levulose. 
Fats 
The fats or lipins are esters of glycerol and certain organic acids 
which have come to be known as fatty acids. When three molecules of 
palmitic acid unite with glycerol, the fat plamitin is secured, as follows: 
H O H - O 
| \ | o 
H—C—OH HO-O—CisHss H—O—-0—C—CisHss 
S Vi 
H—C—OH HO—C—C15H31 _—> H—C—0—C—& 1531 +3H2O 
O 
\, Va 
H—C—O# HO—C—CisHa1 H—C—0-C—C ys 
H H 
Glycerol Palmitic acid Palmitin Water 
When fats are broken up either by bacterial enzyme or other action, 
they are resolved into glycerol and fatty acids. This process is known 
as saponification. 
Action of Bacteria on Fats. There is much evidence that fats are 
split to fatty acids and glycerol by bacteria, although many text books 
