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METHODS OF COCOA ANALYSES. 951 
Mansfeld.'—Five grams of cocoa, or 10 grams of chocolate, are mixed with an equal 
weight of sand and extracted in a Soxhlet apparatus with petroleum ether. 
Wolfram? uses petroleum ether for the extraction of the fat. 
Qualitative examination of the fat.°—The Association of Swiss Analytical Chemists+ 
recommends the determination of the melting point by Riilhdorf’s method, Hiibls’ 
iodine number, and K6ttstorfer’s saponification number. Bjérklund’s ether test and 
Filsinger’s ether-alcohol test are also stated to be of value. 
Bjorklund? covers about 3 grams of the fat in a test tube with double its weight of 
ether, closes with a cork, and tries to bring the mass m solution by shaking at 
18° C. When wax is present, a cloudy solution results, which is not changed by 
warming. If the solution is clear, the tube is placed in water at 0° C. and the time 
observed after which the solution begins to become milky or to deposit white flakes ; 
then the temperature is noted at which the mixture becomes clear on removing from 
the water. When the solution becomes cloudy after ten tofifteen minutes and at 19° 
to 20° C. isagain clear, the cocoa butter is pure. Foracocoa butter containing 5 per 
cent of beef tallow, these numbers are eight minutes and 22° C.; 10 per cent tallow, 
7 minutes and 25° C., ete. 
Dieverich.°—Equal parts of the fat and paraffin are melted together, a drop of the 
mixture placed on a slide and covered with a cover glass. After twelve hours this 
is examined with a power of 20 diameters and polarized light, at a temperature not 
exceeding 5° C. Pure cocoa butter shows palm-leaved crystals; 10 per cent of tallow, 
circular group of crystals. 
Filsinger.7—The iodine and Kéttstorfer’s numbers are determined in the dried fat. 
If these leave any doubt, Bjérklund’s ether test or Filsinger’s ether-alcohol test may 
be applied. This writer has modified the ether test as follows: 2 grms. of fat are 
melted in a graduated tube with 6 cc. ot a mixture of 4 volumes of ether (sp. gr. 0.725) 
and 2 volumes of alcohol (sp. gr. 0.810), shaken and set aside. The pure fat gives a 
solution that remains clear. 
Hager’s anilin test® is conducted as follows: About 1 gram of cocoa butter is 
warmed with 2 to 8 grams of anilin until dissolved; the mixture is allowed to stand 
1 hour at 15° C., or 1} to2 hours, when temperature is 17° to 20° C. . Pure cocoa butter 
floats as a liquid layer on the anilin. If the cocoa contains tallow, stearic acid, or 
a little paraffine, cloddy particles, which remain hanging on the upper wall, on 
gentle agitation are deposited in the oil layer; if wax or much paraftin is present, 
the oil layer solidifies; if much stearic acid is present, there will be no separation 
into two layers, but the whole solidifies to a hard crystalline mass; with pure cocoa 
butter, the oil layer hardens only after many hours. A parallel test should be made 
with pure cocoa butter. 
Hassall.°—Melting point is determined. Foreign fats become rancid and tallowy 
in a few days. 
Herbst.'°—Melting point determination and Bjérklund’s ether test are recommended. 
! Op. cit., note 1, p. 950 of this work. 
?Jahresbericht d. k. chem. Centralstelle f. 6ff. Gesundheitspflege in Dresden, 
1878; Zeitsch. f. anal. Chem., 18, 346. 
3 See table on page 938 for the chemical and physical constants for cocoa butter. 
* Op. cit., note 3, p. 949 of this work. 
° Zeitsch. f. anal. Chem., 3, 233; see also op. cit., note 2, p. 938 of this work. 
° Geschifts-Ber. d. Papier- u. chem. Fabrik in Helfenberg, 1883; Zeitsch. f. anal. 
Chem., 23, 567. 
*Zeitsch. f. anal. Chem., 19, 247; Chem. Ztg., 1889, 13, 309; see also op. cit., note 2, p. 
938 of this work. 
8 Zeitsch. f. anal. Chem., 19, 246; see also op. cit., note 2, p. 938 of this work. 
° Op. cit., note 2, p. 940 of this work. 
10 Op. cit., note 4, p. 950 of this work. 
