950 FOODS AND FOOD ADULTERANTS. 



scrapes chocolate with a knife to prepare it for analysis. Mansfeld 1 recommends 

 that the material be finely rasped or powdered . 



Determination of moisture. The Association of Swiss Analytical Chemists 2 makes this 

 determination in cocoa powder. Two grams are spread in a thin layer on a watch 

 glass and dried to constant weight at 105 C. Beusemann 3 dries 2 grams to a con- 

 stant weight at 100 C. ; Herbst, 4 a weighed quantity, mixed with twice its weight 

 of sand, at 60 to 80 C. ; Mansfeld, 1 5 grams to constant weight at 100 C. 



Quantitative and qualitative examination of the ash. For quantitative determination, 

 the method of the Association Swiss Analytical Chemists 2 directs that the material 

 be incinerated in a platinum dish, carefully burned at a low red heat until the ash 

 is white, and after moistening with (NH 4 ). 2 CO3, gently reignited. The ash is also 

 examined qualitatively for mineral substances and pigments; asocher, bolus, excess 

 of alkaline carbonates used in making the cocoa soluble, etc. 



Benseniann. 3 Two grams of material are carbonized, extracted with water, and 

 the residue washed and incinerated. The aqueous extract is added to the ash and the 

 whole evaporated to dryness. The residue is dried at 100 C., weighed, and the result 

 taken as ash. All ashes were of a light gray, almost white, color, so that the addi- 

 tion of ocher, bolus, etc., could be easily detected by a red color of the ash. 



Maiisfeld 1 burns 5 grains at a low temperature and tests the ash for mineral addi- 

 tions; as ocher, excess of alkaline carbonates, etc. 



Stutzer 6 mixes 2 grams with sand, incinerates at a moderate heat, adds NH 4 NO 3 , 

 and ignites again until the ash is white and free from CO.j and nitrates. In a recent 

 article 6 this writer has called attention to the value of the additional determinations 

 of ash soluble in water, total P 2 O S and P 2 O 5 soluble in water, as a means of detect- 

 ing the use of fixed alkalis and ammonia in the process of manufacture. His results 

 are given in the table on page 943. 



Quantitatived etermination of fat. Association of Swiss Analytical Chemists. 2 The 

 sample is mixed with sand, extracted with absolute ether in a Soxhlet apparatus for 

 six to eight hours; the ether is removed by careful evaporation, and the fat dried at 

 100 C. 



Bensemann. 3 Two grams of the substance are rubbed to a powder in a mortar 

 warmed to 60 C., some gypsum being added to facilitate the pulverizing. The mass 

 is extracted with ether in a Soxhlet apparatus and the extract is dried at 100 C. 



Blyth. 7 The best method of extracting the fat is to exhaust the nibs with ether in 

 a Soxhlet apparatus. 



Boussingault. 8 mixes the material with sand and extracts with carbon disulphide. 



Hassall. 9 Three grams of cocoa are dried in the water bath and exhausted with 

 ether; the ether is evaporated off, and the residue dried and weighed. This residue 

 contains some or all of the theobromine, the amount of which must be determined 

 and subtracted from the ether extract. 



Herbst. 4 The residue from the moisture determination "is extracted with ether and 

 the extract dried at 100 C. 



1 Zeitschr. d. allgem. osterr. Apotek. Ver., 44, 329. 



'Vierteljahresschrift ii. d. Fortschritte auf d. Gebiete d.-Chem. d. Nahr. u. Genus- 

 smittel, 1890, 2, 171. 

 3 Rep. f. anal. Chern., 1884, 4, 213. 



Rundschau, 1882, 443; Rep. d. anal. Chem., 2, 236; Zoitsch. f. anal. Chem., 22, 278. 

 6 Rep. f. anal. Chem., 1882, 88 and 165; Hygiene-Bericht, 1882-'3, 1, 217. 

 Op. cit., note 3, p. 939 of this work. 



7 Op. tit., note 3, p. 936 of this work. 



8 Ann. Chem. Phys., [5], 28, 433; Jour. Chem. Soc,, 1884, 46, 202; Chem. Ztg., 1883, 

 203, and 902. 



"Op. tit., note 2, p. 940 of this work. 



