of simple alimentary Substances, fyc. 



101 



of 10 per cent, of its original weight, became of a deep brown 

 colour, and seemed to be partially decomposed *. 



Sugar prepared from starch evidently belongs to this va- 

 riety, as is sufficiently indicated both by its sensible properties 

 and composition. The same is true in general of diabetic 

 sugar, and probably also of the sugar of grapes, figs, fyc When 

 pure, all the varieties of this sugar are beautifully white, cry- 

 stallize in spherules, and are permanent under the ordinary 

 circumstances of the atmosphere. 



Between these two extremes, sugars occur of almost every 

 grade, as the following table will show. 



On some of these it may be necessary to make a few re- 

 marks. The sugar candies of the shops frequently contain 

 minute quantities of foreign fixed bodies, such as lime, &c, 

 as well as others of a destructible character. Both the spe- 

 cimens of India sugar candy I examined were obviously im- 

 pure to the eye, being of a brown colour and deliquescent ; 

 they contained, among other things, traces of potash. The 

 East India refined sugar was perfectly white, but rather soft 

 and friable, and it did not possess the fine and brilliant grain 



* I observed that after this sugar had been cautiously melted it might 

 be preserved in the state of a transparent fluid, if placed in a perfectly dry 

 atmosphere, as under the receiver of an air-pump with sulphuric acid; but 

 that in a few hours after exposure to the air, it began to grow opaque and 

 assume the crystalline form, by attracting moisture. Is not this precisely 

 analogous to the deterioration which is known to take place in the sugars 

 of commerce? See Mr. Daniell on this subject in the Royal Institution 

 Journal, vol. xxxii. Dr. Ure supposes that this deterioration depends on 

 the absorption of oxygen ; but I have hitherto met with no sugar contain- 

 ing an excess of oxygen. 



t In these results fixed bodies only have been allowed for, and those 

 marked (i>), as occurring in commerce, are probably subject to slight varia- 

 tions in their composition. 



of 



