SACCHARUM. 719 



There is also present in the juice a very small amount of a slightly 

 aromatic substance (essential oil ?) to which the crude cane sugar owes 

 a peculiar odour which is not observed in sugar from other sources. 

 The first two classes of the above enumerated substances render the 

 juice turbid, and greatly promote its fermentation, but they easily 

 separate by boiling, and the juice may then be kept a short time with- 

 out undergoing change. In many colonies the yield is said to be far 

 inferior to what it should be ; yet the juice is obtained in a state allow- 

 ing of easier purification, when its extraction is not carried to the 

 furthest limit. 



In beet root as well as in the sugar cane, cane sugar only was said to be 

 present; leery however has proved that in the cane some uncry stall izable 

 (inverted) sugar is always present. Its quantity varies much, according 

 to the places where the cane grows, and its age. The tops of quick- 

 growing young canes yielded a vesou containing 2'4 per cent, of uncrystal- 

 lizable sugar ; 36 of cane sugar ; and 94 of water. Moist and shady 

 situations greatly promote the formation of the former kind of sugar, 

 which also prevails in the tops, chiefly when immature. Hence that 

 observer concludes that at first the uncrystallizable variety of sugar is 

 formed, and subsequently transformed into cane sugar by the force of 

 vegetation, and especially by the influence of light. Perfectly ripened 

 canes contain only ^j to -V of all their sugar in the uncrystallizable state. 



Description and Chemical Composition — Cane sugar is the type 

 of a numerous class of well-defined organic compounds, of frequent 

 occurrence throucfhout the veijetable and animal kincjdoms, or artificially 

 obtained by decomposing certain other substances ; in the latter case, 

 however, glucose or some other sugar than cane sugar is obtained. Cane 

 sugar, C^-H^^O", or e'H"(OH)'0', melts, without change of composi- 

 tion, at 160° C, several other kinds of sugar giving off" water, with which 

 they form crystallized compounds at the ordinary temperature. 



Cane sugar forms hard crystals of the oblique rhombic system, having 

 a sp. gr. of 1'59. Two parts are dissolved at 15° C. by one part of 

 water,^ and by much less at an elevated temperature ; a slight depression 

 of the thermometer is observable in the former case. One part of 

 sugar dissolved in one of water, forms a liquid of sp. gr. 1*2 3; two of 

 sugar in one of water, a liquid of sp. gr. 1*33. Sugar requires 65 parts 

 of spirit of wine (sp. gr. 0"84) or 80 parts of anhydrous alcohol for solu- 

 tion ; ether does not act upon it. 



A ray of polarized light is deviated by an aqueous solution of cane 

 sugar to the right, but by some other kinds of sugar to the left, as first 

 shown by Biot. These optical powers are highly important, both in the 

 practical estimation of solutions of sugar, and in scientific studies con- 

 nected with sugar or saccharogenous substances. The optical as well as 

 chemical properties of sugar are altered by many circumstances, as the 

 action of dilute acids or alkalis, or by the influence of minute fungi. 

 Yeast occasions sugar to undergo alcoholic fermentation. Other ferments 

 set up an action by which butyric, lactic or propionic acid are produced. 



Cane sugar is of a purer and sweeter taste than most other sugars. 

 Though it does not alter litmus paper, yet with alkalis it forms com- 



^ It is commonly stated that three parts can be dissolved in one of cold water ; but this 

 is not the fact. 



