ant
points--the superiority of the hot over the cold mode, and the
necessity for great attention to the operation of tempering. Let them
take a tumbler of cane-juice and a bottle containing lime water, add
the latter to the former by drops, pausing and stirring between each,
and they will find that, after the addition of a certain quantity, the
opaque gummy appearance of the liquor undergoes a change, and the
impurities contained in it separate into flakes, which increase in
size with each drop of lime added, until they become extinct, and the
supernatant liquor perfectly transparent; this is the precise point at
which the liquor is tempered, and each drop of lime added after this,
causes the flakes to diminish rapidly in size, at last entirely to
disappear (being re-dissolved), and the liquor to resume its former
gummy appearance; it is, therefore, evident that there should be no
such expressions as tempering high or low.

The reason why some liquor is so difficult to clean is, that it is
either tempered high or low; if it be exactly tempered, the impurities
contained in it being entirely separated and thrown out of solution,
rise to the surface immediately on the application of heat, and are
easily removed; but if there be too little lime, a great portion
remains in solution, and if too much, a proportional quantity is
re-dissolved; and in either case cannot be removed by any mechanical
means. It is, therefore, necessary to have some precise test for the
application of lime.

As regards the superiority of the hot over the cold tempering, let any
one take, in separate vessels, two gallons of cane-juice, and temper
one, adding the lime in small quantities--say, of three grains at a
time--and keeping an account of the quantity used; he will find that
the first portions produce no effect whatever, and that it is only
after the addition of a considerable quantity that the desired
precipitation of the impurities manifest itself. Why is this? Because
albumen, gluten, resin, and chlorophyle, being soluble in lime, lime
is equally so in them, and they must first be saturated before it will
produce any other effect. Let the liquor thus tempered, be then placed
on one side. Put the other gallon over a fire, and boil it, removing
the scum just before, and during, ebullition; let it then be taken off
the fire, and tempered in the same way as the other. The very first
quantity of lime added causes the appearance of the floccy
pr