954 FOODS AND FOOD ADULTERANTS. 



extracted with water; the extract is evaporated to a sirupy consistency, treated 

 with alcohol, decolorized by means of lead acetate, the excess of which is removed 

 with H.jSO.. The sugar thus prepared is inverted and the invert sugar determined 

 with Fehling's solution. 



Hassall. 1 The sugar is dissolved out of the sample with cold water, inverted by . 

 boiling with dilute H..SO 4 , and then estimated with copper solution. 



Mansfeld. 2 The residue from the fat determination is extracted for three hours 

 with 100 cc of 80 per cent alcohol, and the extract made up to 150 cc. Fifty cc are 

 evaporated to dryness. After weighing, the residue is dissolved in water, made up 



N 

 to 100 cc, heated one-half hour on the water bath with 10 cc T^HCl, neutralized 



with NaOH, and diluted to 250 cc. The invert sugar is then gravimetrically deter- 

 mined with Fehling's solution. 



Determination of sugar 1)y direct weighing. Hassall. 1 Dissolve a weighed quan- 

 tity of cocoa containing sugar in cold water and collect the residue on a filter. This 

 residue is dried on the water bath and weighed. 



100 per cent of insoluble matter=per cent of soluble matter. 

 Per cent of soluble matter (per cent of moisture -f- the approximate 

 per cent of soluble matter in cocoa) = per cent of sugar. 



Herbst. 3 The residue from the fat determination is extracted with boiling 50 per 

 cent alcohol as long as the extract is colored. This extract is evaporated to drynrss 

 and treated with cold water, which dissolves the sugar. This solution .is evaporated 

 to dryuess, the residue dried in hydrogen and weighed. 



Determination of commercial glucose in chocolates. In regard to the determination of 

 the sugars used for sweetening chocolates, M. Schrojder ' writes as follows: 



"The detection and estimation of less than 5 per cent of commercial glucose in 

 presence of cane sugar by means of copper solution is uncertain, because commercial 

 cane sugar often contains an equivalent amount of reducing sugars. The optical 

 determination by Clerget's method is more satisfactory, since only a small percent- 

 age of commercial glucose is necessary to appreciably lessen the degree to which the 

 inverted solution rotates to the left. The evidence obtained by Clerget's method 

 can be strengthened by determining the dextrin which would be present in the 

 residue after fermentation, if commercial glucose were present in the original 

 material." 



Determination of starch. Asborth 5 has published a method, according to wliirli lie 

 adds Ba(OH) 2 to the boiled starch, with which it forms a compound Avlucli is insol- 

 uble in dilute alcohol. Dr. Mansfeld's modification of this method is given helow. 



Ass. Swiss Anal. Chem. K The sample, free from fat and sugar, is boiled with water 

 for four hours and the resulting starch solution is inverted with sulphuric acid ; the 

 excess of acid is removed by basic acetate of lead; the filtrate is freed from lead with 

 H 2 S and the reducing sugars determined by means of Fehling's solution. The 

 starch may also be determined by treating the powder in a Reischauer's pressure- 

 flask, inverting, etc. 



Beusemaun. 7 Two grams of the substance, after extraction and washing with cold 

 water, and while still moist, are mixed with 200 cc of water and 20 cc HC1, sp. gr. 1 . 12. 

 The mixture is heated for at least three hours on the water bath, cooled, and filtered. 

 After making the filtrate alkaline with NaOH, a freshly prepared solution of 4 grams 

 of copper tartrate, 2 grams of tartaric acid, 30 cc of soda lye, sp. gr. 1.13, and 100 



1 Op. cit., note 2, p. 940 of this work. 

 * Op. cit., note 1, p. 950 of this work. 

 3 Op. cit., note 4, p. 950 of this work. 

 Zeitsch. f. angew. Chern., 1892, 173. 



6 Rep. anal. Chem., 8, 20. 



fi Op. cit., note 3, p. 949 of this work. 



7 Op. cit., note 4, p. 949 of this work. 



