428 Conversion of Starch into Sugar. {[Dec. 
peared to have combined with 10 parts of water; while analysis 
gives 20 parts more water in the starch sugar than in the starch. 
It is obvious, however, that the proportion of water obtained by the 
first method must be too small, as in a process of that kind it is 
very difficult to avoid all loss, besides that which is occasioned by a 
commencement of roasting. 
Analysis of the Sugar of Grapes. 
I obtained the sugar, with which the following experiments were 
made, from Mr. Pautex, by whose labours the manufacture of 
sugar of grapes has been greatly improved. 
100 parts of sugar of grapes, dried at the temperature of 53°5°, 
and when the hygrometer stood at 75°, when exposed to the heat 
of boiling water, lost 3°14 parts of water; and when burnt left a 
residuum weighing 0°513 parts. 
0°55 centigrammes of the same sugar, dried at 53°5°, when 
burnt, consumed, according to the mean of two experiments, 
34°21 cubic centimetres of oxygen gas, and formed 36°17 cubic 
centimetres of carbonic acid gas. Hence 100 parts of sugar of 
grapes, dried at the temperature of boiling water, are composed 
as follows : 
Carbon. .... 36°71 Ww 
’ LC IG RB ie iced tick ..08 
Hea di 5631 bo Bain in exCGSS FS Ss ao 
100°00 
The result of this analysis of sugar of grapes does not differ 
farther from that of starch sugar, than is usual in two different ex- 
periments upon the combustion of the same body. These two 
sugars likewise approach so near each other in all their other pro- 
perties, as to render it probable that they constitute only one species. 
They both melt at the temperature of boiling water; they have 
both the same sweet and fresh taste; they both undergo the vinous 
fermentation ; they both crystallize confusedly in spherical crystals ; 
they are both equally soluble in water and in weak alcohol ; and all 
the differences which exist between them are analogous to those 
which we frequently tind between sugar of grapes from two differ- 
ent varieties of grapes. 
Sugar from the cane and from beet differs much from these two, 
and from all other sugars, by containing a greater proportion of 
carbon. According to the analysis of Gay-Lussac and Thenard, 
100 parts of the sugar of the sugar-cane contain between 42 and 
43 parts of carbon, and the oxygen and hydrogen are so graduated 
as to form water without any residue. I have obtained the same 
result, except a small excess of oxygen above the elementary 
water, which might very well be owing to an errorin my expe~ 
riment, 
