DECOMPOSITION OF SUGAR BY A LOW HEAT, 149 
Some of these are starch, dextrine (cane gum), grape 
sugar, and cane sugar. They seem to be mutually con- 
vertible in the growing plant, and by the action of heat 
upon the juice, assisted by merely the presence of an acid, 
are capable of being transformed, the one taking the form 
of the other in the order above named,—with the excep- 
tion of the conversion of grape into cane sugar, which no 
art can accomplish, although such a change takes place 
with facility in the growing plant. The occurrence of de- 
grading transformations, or such as follow in the reverse 
order of the substances named, such as that whereby cane 
sugar is made to take the form of grape sugar, or other 
inferior forms during evaporation, is common; indeed it 
may always be inferred to take place when the acid and 
impurities natural to the cane juice have not been neutral- 
ized or removed, although such change may not be immedi- 
ately perceptible, either to the eye or to the sense of taste. 
It is a great error to suppose that no such change is taking 
place unless the effects of the decomposing power of heat 
are visible to the eye. Heat, with the presence of an acid, 
will convert cane into uncrystallizable sugar, without any 
marked indications that such a destructive process is in 
progress. 
But a moderate heat alone, if prolonged, is capable of 
decomposing a pure solution of cane sugar. The experi- 
ments of Soubeiran proved this conclusively. He dissolved 
a given quantity of sugar in a given quantity of water, and 
applied heat to the solution for 36 hours. ‘The apparatus 
was so constructed, that the water given off by evaporation 
was continually returned to the original solution, by which 
contrivance the latter was always composed of the same 
quantity of sugar, or its derivatives, and the same quantity 
of water, as when the experiment commenced. Gradually 
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