952 FOODS AND FOOD ADULTERANTS. 
The small quantity of sesame oil, added to give the broken surface of chocolate a 
smooth appearance, can not be detected with certainty. 
Mansfeld.'—The purity of the fat is determined according to Filsinger. The || 
melting point is determined according to Pohl. 
Schedler.2—The comparatively high commercial value of cocoa butter brings adul- 
teration with waxes, stearin, paraffin, and beef tallow. The taste, odor, melting point, 
and ether test are mentioned as means of detecting foreign fats. Paraffin gives cocoa 
butter a soapy feel and lowers the specific gravity. An addition of stearic acid is 
made known by the high melting point and by boiling with dilute N,OH, when the 
stearic acid goes into solution as stearate of sodium and is reprecipitated by H.SOx,. 
Determination of theobromine.—Blyth.?—This author outlines the methods of Wosk- 
ressnsky, Mitscherlich, and Wolfram. He also gives the following ‘‘speedy method of 
determining, with fair exactitude, the per cent of theobromine in cocoa”: Weigh out 
a definite portion and exhaust it with petroleum ether. Mix the residue with a 
little burnt magnesia and water, evaporate to dryness at 60° to 70° C., and exhaust the 
residue with boiling 80 per cent alcohol, which dissolves out the theobromine. After 
driving off the alcohol, the residue may be purified for weighing by washing with 
petroleum ether. 
Boussingault.A~—Extract the sample with boiling water and precipitate the decoc- 
tion obtained with basic acetate of lead. After removing the excess of lead with 
HS, evaporate to dryness and exhaust the residue with boiling alcohol. On cool- 
ing this solution the alkaloid separates out as a crystalline powder. 
Hassall® uses the method devised by Hehner for the estimation of caffeine in tea, 
which is conducted as follows: Twenty grams of material are boiled with about a 
liter of water, cooled, and the solution made up to the mark and filtered. Five hun- 
dred cc of the clear filtrate are evaporated on the water bath with the addition 
of a little MgO. The dry residue is extracted with boiling alcohol. The united 
extract is evaporated nearly to dryness, taken up with ether, filtered, and evapo- 
rated to dryness for weight. 
Legler® gives the following modification of Wolfram’s method: 20 to 25 grams of 
cocoa, or 50 grams of chocolate, deprived of fat, are digested several hours with 4 
per cent H,SO,. The solution is filtered and the theobromine precipitated with 
sodium phosphomolybdate. After standing twenty-four hours, filter, wash with 6 to 
8 per cent H,SO,, and dissolve the precipitate in NaOH or Na,CO;3. Add sufficient 
H,SO, to the solution to leave it slightly alkaline, evaporate with sand, dry at 110° 
C., and extract at 70 to 90° C., with amyl. alcohol. Evaporate the extract to dry- 
ness ina platinum dish, dry, and weigh. Ignite the residue and weigh again. The 
difference is the weight of the theobromine. 
Mansfeld.'—Another portion of 50 ce of the alcoholic extract, obtained by the 
author’s method for the determination of sugar (see methods for determination of 
sugar on page 954), is evaporated to dryness with MgO and the finely powered residue 
extracted in a Soxhlet’s apparatus with CHCl;. The extract is evaporated to dry- 
ness and the residue dissolved in boiling water. The solution is filtered, evaporated 
to dryness, and the residue of theobromine weighed; the alkaloid thus obtained is 
pure. 
Mulder.’—Ten grams of cocoa are rubbed to a paste with water and boiled for fifteen 
minutes; some MgO is now added and the mixture evaporated to dryness on the water 
1 Op. cit., note 1, p. 950 of this work. 
2 Op. cit., note 2, p. 936 of this work. 
3 Op. cit., note 3, p. 936 of this work. 
4 Op. cit., note 2, p. 941 of this work. 
5 Op. cit., note 2, p. 940 of this work. 
6 Ber. d. Chem. Ges., 15, 2938; Zeitsch. f. anal. Chem., 23, 89. 
7 Op. cit., note 8, p. 938 of this work. 
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