SUGAR 



927 



The specific gravity of crystallised cane-sugar is 1*594. Crystallised cane-sugar 

 seems to be the most complete type of sugar known. Its crystals are the largest and 

 most regular, and its taste the sweetest. These crystals are rhomboi'dal prisms, and 

 appear largest in the form of sugar-candy. When boiled much or heated with acids 

 it would appear that a lower form of sugar resulted, namely, grape-sugar. 



At 300 sugar loses 0'6 per cent., and remains uninjured after seven hours ; it melts 

 at 320, and at this point it seems to have lost some of its sweetness, and probably a 

 portion of water. The same result is obtained at a lower temperature if more time 

 is allowed. The colour is changed to an orange-yellow at 410 : the sugar loses 

 three equivalents of water, becomes gradually brown, has an empyreumatic taste, and 

 is called caramel. With a heat approaching to a red heat, carburetted hydrogen, 

 carbonic acid, acetic acid, and empyreumatic oils are produced, and carbon remains, 

 amounting to 25 per cent, of the original mass. 



Solutions of sugar are decomposed by caustic alkaline solutions, and by hot solutions 

 of the carbonated fixed alkalis. Under these must be included both baryta and lime, 

 if heat is to be long used : both of these substances form compounds with sugar. The 

 compound of sugar and lime is very soluble in cold water, but is precipitated on heat- 

 ing. The amount dissolved is shown to be of true equivalent, by the inquiries of 

 Peligot, who has proposed an ingenious method of ascertaining the amount of sugar in 

 a solution by the estimation of the lime which it will dissolve. The lime in this pro- 

 cess is estimated alkalimetrically by means of an acid. The following table has been 

 constructed by M. Peligot for calculating the results (see next page). 



Saccharimetry. We now come to the estimation of sugar, which is most simply 

 performed by the hydrometer, when the solutions are pure and the kind of sugar 

 known. But commercially it is required to ascertain the proportions of cane-sugar, un- 

 crystallisable sugar, water, and impurities, and this is accomplished most successfully 



