1815.] Conversion of Starch into Sugar. 427 
This explanation of the change of starch into sugar will be fully 
confirmed by my 
Analysis of Starch and Starch Sugar. 
I burnt 57 milligrammes of starch, which ld been dried in the 
mean temperature of the atmosphere, in oxygen gas. ‘This com- 
bustion consumed 40°31 cubic centimetres of oxygen gas, and 
there were formed 43°83 cubic centimetres of carbonic acid gas 
and 0°12 cubic centimetre of azotic gas.* 
In another experiment, 48 milligrammes of starch dried in the 
same way consumed 33°99 cubic centimetres of oxygen gas, and 
produced 34°80 cubic centimetres of carbonic acid gas and 0°16 of 
azotic gas. . 
lf we take the mean of these two experiments, we find that 100 
parts of starch dried at the temperature of boiling water, and ab- 
stracting the ash which they contain, are composed as follows: 
Carbon..... 45°39 
Oxygen..... 48°31] NVOteE sce ea a escee. 9048 
Hydrogen .. 5:90 (°" 2 Oxygen in excess..., 3°76 
Azote...... 0°40 
~ 100°00 
On the other hand, 53 milligrammes of starch sugar prepared as 
above described, and dried at the temperature of 52°, consumed 
when burnt 34°59 cubic centimetres of oxygen gas, and there were 
produced 36.07 cubic centimetres of carbonic acid gas. 
In a second experiment, 63 milligrammes of starch sugar con- 
sumed 37°755 cubic centimetres of oxygen gas, and produced 
39°584 cubic centimetres of carbonic acid gas. 
The mean of these two experiments gives the composition of 
starch sugar, abstracting the ash, as follows : 
Carbon..... shar | ae Water ..... ease oie ae 
Hylfored rind Oxygen in excess .... 4°26 
100°60 
When we compare together these analyses of starch and 
starch sugar with each other, we find that they give us the same 
result as the synthetical experiments, namely, that the only differ- 
ence between the sugar and the starch, is that the former contains 
a greater proportion of water as a constituent than the latter. But 
in the quantity of this water the two methods of experimenting 
differ from each other. When 100 parts of starch, dried at the 
temperature of boiling water, were changed into sugar, they ap- 
* The azote did not appear as a gas, but as a constituent of subcarbohate of 
ammonia, But I have here stated its amount, supposing it in the gascous state, 
6 
