DETERMINATION OF FIBER. 955 
ec water are added. The mixture is slowly heated to 70 to 80° C. and kept at that 
temperature for one-half hour. After completely cooling the Cu,0O is collected on a 
filter, washed cold, dried at 100 to 110° C., and weighed. 
1 gram Cu,0 = 0.45315 grams of starch. 
Hassall! gives a method similar to that of the Ass. Swiss. Anal. Chem. given above. 
Mansfeld.-—Two portions of 25 grams of cocoa, or 5 grams of chocolate, are 
weighed out and placed in 250 ce flasks with 100 ce ot water in each. One sample is 
heated on the water bath; thé other is placed in water at 30 to 40° C., and shaken 
to emulsify the fat. After thirty minutes the cooled samples are shaken with 50 ce 
of a standard solution of Ba(OH), and 45 per cent alcohol added until the liquid 
reaches the mark. Cool and make up with similar alcohol if necessary. The 
Ba(OH), solution is titrated by mixing 50 ce with 100 cc of water and making up 
to 250 ce with 45 per cent alcohol, using N/,;, HCl with phenolphthalein for an indi- 
cator, and titrating 50 cc. The sample is allowed to settle, and 50 cc of the yellow 
supernatant liquid titrated. The difference between these two titrations for pure 
chocolate is 1.25 cc. The general increase for each per cent of flouris 0.3¢ec. Hence: 
xX -10 ooo 
N/io HCl required. X — per cent of foreign starch in the sample. 
D—number of cubic centimeters difference between the amounts of 
Mansfeld.°—The residue left after the removal of petroleum ether and alcohol 
extracts is driéd and mixed with 500 ce of water; the mixture is heated for 
one-half hour on the water bath, diluted to 1,000 ce, cooled to 55° C., and mixed 
with 0.1 gram of Lintner’s diastase, which has been previously rubbed up with a 
little water. Keep at 55° to 60°C. until iodine gives no reaction for starch, decant 
into a 1,500 ce flask and make up to the mark. Heat 100 cc of the clear liquid 
with 10 ce HCl, sp. gr. 1.125 for three hours on the water bath, cool, neutralize, 
dilute to 500 ce and determine the dextrose gravimetrically. 
_ Schroeder.*—For the inversion of the starch, 3 grms. of the material with 50 cc of 
water and 1 ec HCl (38.8 per cent) are heated for 1 hour under a pressure of one atmos- 
phere. Results of experiments are also reported to show that this treatment does 
not convert an appreciable amount of cellulose into dextrose. 
Weigmann® uses diastase solution prepared as directed by Stutzer. Ten grams of 
cocoa, deprived of fat, are boiled one quarter hour with water and made up to 500 cc; 
250 ce are removed after shaking, treated with 2 ec of diastase solution for four 
hours at 60° C., inverted with 20 cc HCl, neutralized and precipitated with lead 
acetate. After removal of the excess of lead with H.,SO,, the filtrate is made up to 
500 ce and the reducing sugar determined gravimetrically. 
Detection of flour in cocoa preparations.—Reinsch.°—Boil one part of the material 
with ten parts of water, cool and filter. If the sample is pure it will filter rapidly, 
give a clear filtrate, having a light reddish color, and leave a residue that is not 
gummy. If flour has been added, it filters murky and slowly, and a gummy mass 
remains on the filter. 
Determination of fiber.—Ass. Swiss Anal. Chem.’ used Henneberg and Stohman’s 
method. This, as well as a method given by Mansfeld, does not differ materially 
from the official method of the Association of Official Agricultural Chemists, an out- 
line ot which is given on page 958. 
1 Op. cit., note 2, p. 940 of this work. 
?Zeitsch. f. Nahrungsmittel-untersuchung ii. Hygiene, 1888, 1, 2; Deutsch. Chem. 
Zig., 3, 91. 
2 Op. cit., note 1, p. 950 of this work. 
4Zeitsch. f. angen. Chem., 1892, 173. 
° Op. cit., note 8, p. 938 of this work. 
°Fiirther Gewerbe Ztg., 1868, 63; Zeit. f. anal. Chem., 8, 514. 
7 Op. cit., note 3, p. 949 of this work. 
