soluble in water, and is used extensively to
colour wines and sauces, producing all
tints from a light amber to an almost black, and
having the advantage, when properly prepared,
of being free from taste and smell. A solution
of sugar will dissolve a large quantity of lirne,
and such a mixture, when containing but a
small amount of lime, or even alkali, will act
upon—a purer sugar does not— copper vessels.

The commonest forms of fruit sugar are honey
and treacle. In the former it is associated with
grape sugar, and in the latter with cane sugar.
It is called fruit sugar from being the cause of
the sweetness of most of the fruits of temperate
climates, those of tropical climates being said to
owe their sweetness generally to cane sugar.
By some very recent experiments in France, it
has been shown that the sweet principle, as it
first appears in the fruit, is cane sugar, which is
changed wholly or partially into fruit sugar by
the process of ripening, Fruit sugar cannot be
made to crystallise, and is, therefore, hardly to
be met with in a solid form. When a solution
of our household sugar is boiled for some time
it is partly converted into fruit sugar, which has
the property of preventing the crystallisation of
a large quantity of the unchanged cane sugar.
This accounts for the formation of molasses,
there being formed during the long evaporation
of the cane juice much fruit sugar, which
subsequently drains away. Under the heat of the
refining process we, for a like reason, get treacle
as a thick uncrystallisable syrup, carrying,
of course, much cane sugar with it in solution.

The change from cane into fruit sugar takes
place more quickly when there is malic, tartaric,
or almost any vegetable acid present; thus in
making fruit preserves, the acid of the fruit, by
boiling with the sugar, soon changes the whole
of it into fruit sugar, so that on subsequent cooling
there is no crystallisation as there would be
if this change did not occur. Where preserves,
jellies, honey, &c., are kept for some time they
are apt to undergo the disagreeable change
commonly known as candying. This is caused by
the gradual conversion of the fruit sugar into
grape sugar, the warty crystalline lumps of which,
diffused through the mass, give rise to the peculiar
change in taste and appearance. The change
may generally be observed to have taken place
on the surface of jams when the part below is
quite unaffected. The crust of sugar that
surrounds most dried fruits also comes by reason of
the property fruit sugar has of passing, under
certain circumstances, into grape sugar.

Grape sugar (so called because it was first got
from dried grapes), though it is not used to
nearly the same extent as the other two, is
perhaps the most interesting, as it is the only one
that is directly fermentable. The others must
change into grape sugar before they will
ferment, and the same change also takes place
during digestion in the stomach. Nearly all the
substances belonging to the before mentioned
sweet or glucic group can be more or less
readily turned into grape sugar. Thus, when
starch is boiled for a short time with dilute
sulphuric acid, it assimilates the elements of water
and is changed into grape sugar, the acid taking
no part in the change, except giving the impulse
to it, for that can be withdrawn unchanged on
the completion of the process. Malt also
contains a substance called diastase, which possesses
to an astonishing degree the property of
transforming starch into sugar. Let any one try the
experiment of adding a little infusion of malt to
a basin of hot and thick arrowroot or gruel, and
allowing the mixture to stand for a few minutes
in a warm place, it will be found that the
previously pudding-like mixture has become quite thin
and fluid from the transformation of the starch.

Again, when any form of vegetable fibre, such
as rags, sawdust, or tow, has oeen digested for
several hours with strong sulphuric acid, and the
mixture, afterwards diluted with water, has been
boiled for some time, the old rags will have
undergone magical change, and will be sugar.
A hundred parts of linen rags will yield one
hundred and fifteen parts of sugar, the increase
weight being due to the elements of water
absorbed during the change.

In France a great deal of grape sugar
is made from starch, and is known as starch sugar.
Much of this is used for increasing the strength
of beer (at expense of quality), by adding it to
the wort before fermentation. It is also said to
be largely employed in France for purposes of
adulteration.

Though grape sugar has the advantage of
being thus easily manufactured, it is at
disadvantage, since it has not so great a sweetening
power as cane sugar, besides that it does not
crystallise so easily, and is therefore more difficult
to come at in a marketable form. Starch sugar,
in its usual form, appears in large concrete lumps
of a light brown colour, and of very slight
crystalline texture; it has an agreeable taste, though
its sweetening power is less than half that of
cane sugar, and it is not so easily dissolved in
water. There is need, therefore, that it be
produced at a much cheaper rate than at present,
if it is ever to be largely consumed for the same
purposes as cane sugar.

Milk sugar is, of all the varieties of sugar, the
least sweet, and is therefore little used, except
for some chemical and medical purposes. It is
manufactured in many localities in Switzerland
by evaporating, after the curd has been
separated, the waste whey to a syrupy state, when
the sugar crystallises out. Milk sugar is found
in the milk of all animals; human and asses'
milk containing six parts in a hundred.

Though cane sugar so closely resembles other
members of the glucic group, differing from them
only by more or less of water or its elements,
yet up to the present time all attempts of
chemists to form cane sugar artificially have failed.
When future researches shall have solved the
problem of the real relation of these bodies to
each other, there can be no doubt that some
process will be discovered for the chemical
production of such sugar as we put into our tea,
but shall hardly be able to compete with nature
in economy.