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every cubic centimetre of fluid, has an observed rotatory power of 16° in a tube 2 decimetres long, the specific rotatory power would be

16 (1)

- 53*33° 2 XOʻ150

and if this were a cane-syrup, the percentage of sugar would be as 738 : 5333 :: 100 : x. But raw sugars generally contain

. more or less invert-sugar; and as glucose has a specific rotatory power of 56° to the right, while lævulose, at a temperature of 57'2° F. (14° C.), rotates 106° to the left, the specific rotation of invert-sugar at 57'2° F. must consequently be

106 – 56 (2)

250

2

to the left. If, therefore, at the temperature of 57°2° F. (14° C.), we obtain a solution of sugar which produces a specific rotatory power of 67°, and we find by Fehling's test that it contains 4 per cent. of invert-sugar, we have the data necessary for estimating the cane sugar. Let a the percentage of invert-sugar by Fehling's test, b the specific rotatory power of the sugar examined, and x the percentage of crystallized cane-sugar,

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The polariscopes now in most general use are those in which the scale, instead of being marked with the angle, has upon it the percentage of crystallized sugar corresponding to that angle, the quantity of sugar used, and the volume to which it is made up, the length of tube being always the same.

In the trade the percentage of crystallized sugar is not regarded as the sole criterion of value. The percentage corresponding to the angle, given by the mixed sugars, is what is called by sugar merchants the percentage of crystallized sugar; and the percentage of ash, as well as the appearance of the sugar, is taken into account along with this indication in fixing the price.

It should also be remarked that beet-sugar, as will be seen by the analyses of various samples, contains very little invert-sugar, so little indeed that it is disregarded on the Continent.

The following table exhibits the specific rotatory power of commercial sugars, with the amount of cane-sugar calculated directly therefrom, and also the quantities of invert-sugar, ash, and moisture :

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If the formula (3) given above be applied to these results, the proportion of cane-sugar indicated will be from 1 to 2 per cent. more than the amount calculated directly from the angle of rotation.

It is sometimes useful to determine the approximate value of a sugar from the specific gravity of its aqueous solution; and for this purpose the following table, which shows the specific gravities of solutions containing from 1 to 66 per cent. by weight of pure cane-sugar, has been prepared :

Parts by Weight.

Parts by Weight.

Specific Gravity of the resulting Solution at 60° F.

(15.5 C.)

Sugar.

Water.

Sugar.

Water.

I

34 35

66 65

2

64

3 4 5 6

36 37 38

63

99 98 97 96 95 94 93 92 91 90 89 88

39 40 41

62 61 60 59

7 8 9 IO

42

58 57 56

43 44 45

II

12

55

54

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53 52 51 50

84

83

1149-31 115428 1159'28 1164.32 1169:40 1174'51 117966 1184.83 1190'05 1195-31 1200.60 1205.93 1211'29 1216.69 1222'14 1227-61 1233'13 1238.69 1244 28 1249 92 1255-59 1261*30 1267604 1272-83 127865 1284'51 1290-42 1296-35 1302:33 1308 35 1314-40 1320-50 1326-64

49 48

19

49 50 51 52 53 54 55 56 57

20

47

21

46

22

45 44

23 24 25 26

43

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27

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Specific Gravity

of the resulting Solution at 60° F.

(15*5 C.)

1003-89 1007.82 IOII*77 1015*75 101976 102379 1027.84 103193 1036'06 1040'21 1044'39 1048.61 1052.86 1057'13 1061.44 1065078 1070*14 1074'54 1078-97 1083.43 1087'93 1092-45 1097'01 110160 1106-22 111087 1115:56 1120°28 1125'04 1129:83 1134064 1139-50 1144.39

82 81 80

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79 78 77 76 75 74

73 72

28 29 30 31 32 33

71 70 69 68 67

65 66

35 34

I

ADULTERATION.

Owing probably to the low price of cane-sugar, and to the difficulty of finding a suitable cheap adulterant, it is remarkably free from sophistication. If glucose or starch sugar were suspected to have been added, the quantity present might be estimated by Fehling's test, or by the polariscope, according to the methods previously described.

Perhaps the most serious deceit now practised upon the consumer of sugar is the sale of the lower products of the refiner as raw sugar. These products, technically known as “pieces,” are caused to crystallize in very small crystals, and thus to hold a comparatively large percentage of water as well as of invert-sugar. They possess much less sweetening power than raw sugar, but having generally less colour are erroneously supposed by the public to combine cheapness with superiority of quality.

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HONEY

HONEY, as is well known, is the saccharine substance collected by bees from the nectaries of flowers, and stored by them in combs for winter use. It consists, as might be expected from its origin, of a mixture of various bodies, the principal of which are dextroglucose, lævoglucose, and a third body, which is probably one of the less known sugars. Besides these there are small proportions of wax, gum, pollen, and other vegetable and some mineral matters.

The odour and flavour of honey vary according to the nature of the plants from which it has been collected. When new, it flows freely from the comb, and crystallizes after a time into a semi-solid mass. This change takes place to some extent in the comb if left for several months, and then heat and pressure are required for its removal. It is probable that the saccharine substances extracted from the flowers undergo modification in the honey-bag of the bees. In connection with this it has been obseryed that bees fed upon a solution of pure cane-sugar readily produce wax therefrom for the formation of the comb.

The third principal constituent referred to as probably one of the less known sugars is only partially fermentable, and has no direct action upon cupric tartrate, but is gradually converted into glucose when boiled for several hours with a few drops of sulphuric acid. Some chemists have represented this body as cane-sugar,

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