Determination of commercial glucose in chocolates. - In regard to the determination of the sugars used for sweetening chocolates, M. Schrcederrites 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 percentage 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. - Asborth5 has published a method, according to which he adds Ba(OH)2 to the boiled starch, with which it forms a compound which is insol-uble in dilute alcohol. Dr. Mansfeld's modification of this method is given below.

Ass. Swiss Anal. Chem.6 - 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 H2S 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.

Beusemann.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 HCl,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 1 grama of copper tartrate, 2 grams of tartaric acid, 30 cc of soda lye, sp. gr. 1.13, and 100 cc 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 Cu2O is collected on a filter, washed cold, dried at 100 to 110° C., and weighed.

1 Op. cit., note 2, p. 940 of this work. 2 Op. cit., note 1, p. 950 of this work. 3 Op. cit., note 4, p. 950 of this work. 4Zeitsch. f. angew. Chem., 1892, 173. 5 Rep. anal. Chem., 8, 20. 6 Op. cit., note 3, p. 949 of this work. 7 Op. cit., note 4, p. 949 of this work.

1 gram Cu2O = 0.45315 grams of starch.

Hassall1 gives a method similar to that of the Ass. Swiss. Anal. Chem. given above.

Mansfeld.2 - Two portions of 25 grams of cocoa, or 5 grams of chocolate, are weighed out and placed in 250 cc flasks with 100 cc of water in each. One sample is heated on the water bath; the 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 cc of a standard solution of Ba(OH)2 and 45 per cent alcohol added until the liquid reaches the mark. Cool and make up with similar alcohol if necessary. The Ba(OH)2 solution is titrated by mixing 50 cc with 100 cc of water and making up to 250 cc with 45 per cent alcohol, using N / 10 HC1 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 flour is 0.3 cc. Hence:

X = 10 D - 1.25/3. D=number of cubic centimeters difference between the amounts of N/10 HC1 required. X = per cent of foreign starch in the sample.

Mansfeld.3 - The residue left after the removal of petroleum ether and alcohol extracts is dried and mixed with 500 cc of water; the mixture is heated for one-half hour on the water hath, diluted to 1,000 cc, 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 cc flask and make up to the mark. Heat 100 cc of the clear liquid with 10 cc HC1, sp. gr. 1.125 for three hours on the water bath, cool, neutralize, dilute to 500 cc and determine the dextrose gravimetrically.

Schroeder.4 - For the inversion of the starch, 3 grms. of the material with 50 cc of water and 1 cc HC1 (38.8 per cent) are heated for 1 hour under a pressure of one atmosphere. Results of experiments are also reported to show that this treatment does not convert an appreciable amount of cellulose into dextrose.

Weigmann 5 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 cc are removed after shaking, treated with 2 cc 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 H2SO4, the filtrate is made up to 500 cc and the reducing sugar determined gravimetrically.

Detection of flour in cocoa preparations. - Reinsch.6 - 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.7 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 outline of which is given on page 958.

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

2Zeit8ch. f. Nahrungsmittel-untersuchung ii. Hygiene, 1888, 1, 2; Deutsch. Chem. Ztg., 3, 91. 3Op. cit., note 1, p. 950 of this work. 4Zeitsch. f. angen. Chem., 1892, 173. 5 Op. cit., note 8, p. 938 of this work.