90 NUTRITIVE PLANTS. 



experiments on the decomposition of sugar by heat. 480 grains of 

 pure sugar were introduced into a coated retort, and heated gra- 

 dually to redness. The products were, 



Pyromucous acid, with a drop or two of oil, - 270 grains 

 Charcoal - - - - - 120 



Carbureted hydrogen, and carbonic acid gas - $0 



480 

 The pyromucous acid required about ?5 grains of a solution 

 of potass to saturate it ; and when thus neutralized, no ammonia 

 was disengaged. Hence sugar contains no azote, unless we suppose 

 a very minute portion to be present in the pyromucous acid ; and 

 even this is not likely. The charcoal burns away without leaving 

 any residue. Hence sugar contains no earth nor fixed alkali. The 

 proportion of the gasseous products was 119 ounce-measures of car. 

 bureted hydrogen, and 41 ounce-measures of carbonic acid gas. 

 The carborated hydrogen, according to the experiments of Cruik- 

 shank, was composed of five parts carbon and one hydrogen. 



These experiments are sufficient to shew us, that sugar is com- 

 posed entirely of oxygen, carbon and hydrogen. It is of course a 

 vegetable oxide. Lavosier has concluded, from a series of expe* 

 riments on the vinous fermentation, that these substances enter into 

 the composition of sugar in the following proportion : 

 64 oxygen 

 28 carbon 

 8 hydrogen 



100 



But these proportions can only be considered as very distant ap* 

 proximations to the truth. 



From the experiments of different chemists, especially of Proust and 

 Gottling, it appears that there are d fferent species of sugar found 

 ready prepared in the vegetable kingdom ; distinguished from each 

 other by the figure of their crystals, and other variations in their pro- 

 perties. Tht j species hitherto examined are three in number, name- 

 ly, common sugar, sugar of grapes, and sugar of beet. As far as 

 is known at present, there is no difference between the sugar of the 

 maple and common grape. 



That grapes contain abundance of sugar has been long known. 

 The due de Bouillon first extracted it from the juice of grapes, and 



