ESTIMATION OF DRY SUBSTANCE.
I443
gretted as especially the dextrin and wort would have introduced colloidal constituents which would in all probability have brought out more strongly the effect of adsorption which phenomenon must of necessity be associated with the changes of the relation of the solution and the Pulp. This investigation was undertaken solely for the purpose of finding conditions which would make it possible to obtain definite and uniform results for the extract in malt, more particularly for the coarse grindings. Although the result may not stand for a completed reaction but rather the attainment of an equilibrium between the solution and the insoluble pulp the method suggested gives results far more uniform than any method heretofore proposed. ST. LOUIS, MO.
[CONTRIBUTIONFROM THE BUREAUOF CHEMISTRY,U.S . DEPARTMENTOF
.%GRICUL-
TI'RE, SUGAR LABORATORY.]
THE ESTIMATION OF DRY SUBSTANCE BY THE REFRACTOMETER IN LIQUID SACCHARINE FOOD PRODUCTS.' BY A H U G H B R Y A N
Received July 8, 1908.
The Abbe heatable prism refractometer has come into use in England and on the continent for determining the dry substance content of sugar house products. On account of its ease of manipulation, and the accuracy of the readings as compared with actual dry substance, it has grown into favor. In 1906, Tolman and Smith2 found that for practical purposes all sugars have the same index of refraction for the same concentration. They prepared a table for whole percentages of sucrose, giving the index of refraction taken at zoo. From their work, they came t o the conclusion that the refractometer is a satisfactory instrunent for determining the soluble carbohydrates in solution under the same conditions as those under which specific gravity can be used. In the same year Hugh Main, chemist of the Tate Refinery, London, England, called the attention of Drs. Wiechmann, Geerligs and Herzfeld, to the employment of the refractometer in estimating dry substance in refinery products. He had prepared a table from which the per cent. of water could be obtained from the refractive index. This table and his work were not published until 1 9 0 7 . ~ He found the readings accurate to 0.1per cent. as compared with the usual methods of estimating water in sirups by drying on sand. Prinsen Geerligs,' a t the suggestion of the above author, Published by permission of the Secretary of Agriculture. THIS JOURNAL, 28, 1476 (1906). a Intern. Sugar Journal, 9, 481 (1907). Ibid., 10, 68-(1908).
'444
'1, €I[.GH
BRY,IN.
tried this instrument on cane sugar house products. He prepared a table of dry substance from the refractive index taken at 2 5 ' ; also a table of corrections when taken at other teniperatures. These are given in the paper. -As it is chiefly the salts which in the determination of the degrees Brix, are the main cause of clicerence between this and the actual dry substance, he decided to tr!. solutions of diterent salts with the refractometer. -1s a result of nunierous experiments, lie found that with equal concentration, the calcium salts have a higher index than sucrose, that sodium salts 1raT.e rather equal iiidices. while those of potash salts are lower. He tried, also. the refractive index of products coming from the decomposition of invert sugar by lime and alkalies and also the total non-sugar left behitid I)? molasses alter fermentation anti distilling-. n'ith these substances, when niisetl \\-it11 sucrose, the dry substance by desiccation agrees vel.?' closely \sit11 that b y the refractive index. 111 an examination of the final molasses of nunierous cane houses, he found the dry substance by refractive ititlex to agree \-cry \vel1 v i t h that b y desiccation. The greatest divergence was 2 . 2 5 per cent. I3dmund 0. von Lippman' has published results of trials of this instrument i n beet sugar houses. The products examined were those which occur throughout the house. In the purer products the difference between the actual dry substance and dry substance b y refractometer are x-ery small, while in the final molasses these diKerences are slightly more. Yet in these latter cases, the widest difference does not make more than 1.5 per cent. difference in purity, and the average is under 0.5 per cent. difference. As compared with Brix reading (I)!. pycnometer or spindle), the refractive index, in every case, is much nearer the actual dr?, substance. Where the products are very dark in color. and a n end-point in reading is hard to obtain or where the sample uiider examination contains crystals of sugar the sample can be diluted half and the reading made. The dry substance, when calculated from the hall dilution, is nearer the actual dry substance than Tvhen undiluted 1Ie used Mains's tables. The purpose of this paper is to give results of deterniinations of dry substance, using this instrument along ivith the actual dr!. substance i n honeys, sirups, molasses, etc. Coiriparisou of results whose readings were made at different temperatures, sllonwl the table o f corrections to be as near correct as one could desire, so for most work the table of Geerligs is most available. The method used for determination of actual dry substance was the one ordinarily used for sugar products, viz.,drying to constant weight of 3 to ,j grams on I O to 1.j grams of sand in a flat-bottomed dish a t 70' in a \~act~uiii oven. The drying was considered finished wheii the difference between two successive ireighings,
* Deut. Zuckerind, 33,
106, 174 and 244 (1908).
GEERLIGS'STABLEFOR DRY SUBSTANCE
--
1.333' 1* 3341 I . 3361 I . 3371 1* 3394 1* 3405 I . 3424 1 * 3435 I * 3454 1* 3465 __ 1.3484 1.35"C 1.3516 1 353C I * 3546 I . 3562 1.357s 1 3594 1.3611 I . 3627 1.3644 I . 3661 I . 3678 1.3695 1.3712 1* 3729 1* 3746
3764 I . 3782 I . 3800 I . 3818 I . 3836 1.3854 I . 3872 I . 3890 1.3909 I . 3928 1.3947 I . 3966 1.3984 1.4003 1
9
.4023 1.4043 I . 4063 I
tance.
1
Decimals.
Per cent.
- _ .
I
DV sub. Index
BY ABB$ REFRACTOMETER, AT 28OC.I
Index.
cent.
0.0001=0.05
2
0.0002=0. I
3 4 5
0. 000,7=o. 2
G
0.0006 = o . 4 0.0007=0.5 0.0008 =o. 6 0.0009=0.7
0.0004=0.25
0.0013=0.85
' 1.416C
0. 0005 =o. 3
7 8 9 IO
-~ 0.0005 = o . 25 0.0016=0.8 46 0.0006 =o. 3 0.0017=0.85 47 0.0007=0.35 0.0018=0.9 48 o.oO08=o. 4 0.0019=0.9j 49 0.0009 =o. 4 j 0.0020=1.0 50 0.0010=0.5 0.0021 = I ,0 51 o.oorI=o.~~ 52 53 54 _ .
11
o .oo01= o . 0 5
12
0.0002=0. I 0.0003=0.2 0.0004=0.25 0.0 0 0 5 =o. 3 0.0006 = o ,4 0.0007 =o. 4 j
I3 I4 I5 16 17 I8 I9
0.0009 =o. 6 0.0010=0.6j
21
0.0011=0.7
22
23 24
0.0012=0.75 0.0013=0.8 0.0014=0.85
27
1 0.0001=0.05
;:
o.m2=0.1 0.0003=0.15 0.0004=0.z
28
~
o.ooo5=0.25
~
0.0006=0.3 0.0007=0.35 0.0008-0.4 0.0009=0.45 o ooro=o.g 0.0011=0.55
I . 429:
55
1.4314 1.4335 1.4355 I . 4382 1 440: I. 4428 1.4451 1.4474 1 . 4497 1.452C 1.4549 1.4567 1.4591 1.461s
56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71
3
0 . 0 0 0 8 =0.5
20
31 32 33 34 35 36 37 38 39 4O 41
Decimals.
Per
i
I
Dry subtancc
1
0.0013=0.55 0.0014=0.6 0.0003=0. I 0.001g=o.65 0 . ~ 4 = 0 . 10.0016=0.7 ~ 0 .0005 = o .2 0.0017=0.75 0.0002=0.1
0.0006=0.25
0.0018=0.8
0.000j
=o. 3 0.0008=0.35 0.0009 =o. 4 0.0010=0.4j 0.0011=0.5 0.0012=0.~
0.0019=0.85 0. 0 0 2 0 = 0 . 9 0.0021=0.9 0.0022=0.95 0.0023= I .o 0.0024= I .o
0.0001=0.0
0.001~=0.55 0.0016=0.6 0.0017=0.65 0.0018-0.65 0.0019=0.7 0.0020=0.75
72
0.0013=0.65 0. ob14 =o. 7 o.oorg=o.75 0.0016=0.8 0.0017=0.85 0.0018=0.9 0.0019=0.95 0.0020=1.0 0.0021=I
.o
1.4711 I . 4736 1.4761 1.4786 1.4811 I . 4836 I . 4862 I . 4888 1.4914
,4966 1.4992 I I . 5019 I . 5046 o . m 1 = 0 . 0 5 1 0 . 0 0 1 ~ = 0 . 6 1.5073 42 43 o . o o o z = o . ~ ~ 0 . 0 0 1 3 = 0 . 6 5 r . g r m 1.5127 44 0.0003=0.15 lo.oo14=0.7 ~
0.0001 = o . o j
I
73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90
0 . 0 0 0 2 = o .0 5
0.0003=0. I 0.0004=0.15 0.0005 - 0 . 2
0.0006 =o. 2 0.0007=0.25 0.0008 = o .3 0.0009 =o. 35 o.0010=0.35 0.0011=0.4 0.0012=0.45 0.0013=0.5 0.0014=0.5
0.0021=0.8
0.0022=0.8 0.0023 =o. 8j 0.0024 = o . 9 0.0025=0.9 0.0026=0.95 0.0027 = I . o 0 . 0 0 2 8 = I. o
I446
A . IIUGII BRYAS. ?'.lBLI
