958 FOODS AND FOOD ADULTERANTS. 
lead acetate were then added and the mixture again shaken. After allowing it to 
settle, the clear liquid was decanted through an asbestos filter and water added to 
supply its place. This was in turn decanted, and so on until the filter began to clog, 
when just enough acetic acid was added to the material in the flask to turn it red. 
Decantation and filtration were then continued till the filtrate came through color- 
less. Under these conditions filtrations were rapid and filtrate extremely clear. 
The asbestos filter and contents were then placed in the flask, water enough added 
to bring the whole to about 100 cc, and the flask placed on the steam bath for 
three hours. At the end of this time 10 ce of concentrated HCl were added, and 
the heating continued three hours more. After cooling, NagCO3 was added until the 
contents of the flask became blackish. The whole was now washed into a 250 ce 
flask and made up to the mark. Dextrose was oxidized by Allihn’s method, 25 ce 
of solution being used, and the resulting Cu,O collected on a Gooch crucible, redis- 
solved in HNO;, converted into CuSO,, and the Cu determined electrolytically. 
Five samples of commercial starchy materials were examined for the purpose of 
determining the amount of starch converted to dextrose by the method employed. 
Three grams of material were heated on the steam bath for three hours with 200 ce 
of water; 20 ce of HCl. (sp. gr. 1.125) were then added and the heating continued 
three hours longer. After neutralization with Na2:CO; dilution to a definite volume, 
and filtration from the slight residue, the dextrose was determined by Allihn’s 
method, the amount of Cu,0 being determined electrolytically. Duplicate samples 
were inverted and duplicate weighings made from each inverted solution. The 
results were as follows: 
Percentage of starch in commercial starchy materials used in manufacture of cocoa prepara- 
tions, i. e., per cent of dextrose obtained by inversion X 0.9. 
[ All samples were air-dried. | 
Solution No.1. | Solution No. 2. 
Character of sample. Mean 
sity a Ie ge eeu 
Wah catshoun et ee take 222 Moise mae mae evan meee ere eerste | East 71.3 71.6 | (ls (3) 71.6 
Berm day eeLOWOOn 2 sais 2 eee 5 2c eS SRE Dae 82.5 82.3 81.9 81.7 82.1 
@ornbutanchimssseecre ye. ee eerste he pe ee ern See ep Ee 3.6 83. 8 84. 2 83. 8 83.8 
HO CAbONT OUT se oe) a so es yea ee ee ES eae Beier ees j  LY 81.7 79.3 79. 2 80.5 
eTeparedicassaviasbarehy cases en eae eee eee yeep | SBN ives eee 8455) |b aes 84.1 
| 
Starch determinations are only reliable when the conditions are held 
rigidly exact. In order that this may be made more certain each set 
of determinations should be accompanied by a check determination with 
material of known dextrose-yielding power. 
Determination of fiber.—The official method of the Association of Official Agricul- 
tural Chemists ! was adapted to this work, as follows: Two grams of material were 
placed in a long narrow test tube with a lip, washed with several portions of ether, 
decanting through a Gooch crucible. After evaporation of the ether, the material in 
the tube and crucible was washed into an Erlenmeyer flask with 200 ce of 1.25 per 
cent H.SO,. After boiling a half hour with a reflux condensing tube, the solution was 
filtered through a linen filter, and the residue thoroughly washed with hot water; 
while still hot, the filtrate was refiltered through a Gooch crucible, and the shght 
residue again thoroughly washed with hot water. The material on the linen and in 
the crucible was rinsed back into the flask with 200 ce of 1.25 per cent NaOH, and 
the boiling and filtration repeated. The material on the linen was then washed into 
— 
' Bulletin No. 31, Chem. Div., U. 8. Dept. of Agriculture. 
en Sa ere: 
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