10 MITSCHERLICH ON CHEMICAL REACTIONS 
water, proceeds with a rapidity proportioned to the greater quan- 
tity of sulphuric acid employed. 
The same transformation may be effected by using nitric acid, 
when an intermediate product is obtained, which offers some in- 
terest. Forty parts of dry starch are moistened with one and 
a half part of water, adding to it afterwards 2 per cent. of the 
weight of the starch of nitric acid; this mixture is then dried, 
first in the open air, and afterwards in the water-bath. ‘The dry 
residue dissolves completely in water, and on taking only five 
parts of water for one part of residue, the solution gelatinizes 
on cooling. In this state it much resembles the jelly furnished 
by many mosses, and which is generally prepared from lichens 
and seaweed. If this solution is boiled for a long time, and 
especially if a little acid be added to it, it loses the property of 
gelatinizing. The formation of dextrine and glucose is owing to 
the fixation of water determined by the action of the acids. 
The conversion of starch into dextrine may also be effected 
by means of a temperature of 150°. Thus acids and heat act 
in this case precisely as platinum and heat in the combination 
of hydrogen with oxygen. Diastase, at a temperature of 75°, 
acts, with respect to the starch, like acids. As no one has 
hitherto succeeded in obtaining this body in a pure state, it is 
impossible to prove that it has not undergone some alteration 
during the conversion of the starch; however, as the reaction is 
effected by means of so small a quantity of diastase, even impure, 
we may reasonably admit that it really acts only by contact. 
Some hundredths of sulphuric acid, added to a solution of 
cane sugar, are sufficient, even without the assistance of heat, 
to convert it into glucose, so that the presence of this body in 
the liquid may be demonstrated by means of sulphate of copper 
and potass. Other acids also produce the same change without 
the application of heat. Acetic acid acts in a similar manner, 
but requires the assistance of heat. 
It is for this reason that lime is added to the saccharine juices 
of plants from which it is desired to extract cane sugar. I have 
examined the juice of beetroot, and I have always found it per- 
fectly neutral, so that the transformation of which we have just 
spoken is impossible in the beetroot itself; but any wound may 
cause the production of acids, and then the sugar undergoes 
alterations. 
I have obtained the sugar formed by the action of sulphuric 
