ntil it reaches the line 0. The blue tincture of
litmus, which would still be blue, if water had been added, is turned
into rose-color by the action of the acids contained in the must.

"If a solution of 1,369 per cent, of caustic ammonia is added to this
red fluid, and the tube is turned around to effect the necessary
mixture, keeping its mouth closed with the thumb, after the addition of
more or less of the ammonical fluid, it will change into violet. This
tinge indicates the saturation of the acids, and the height of the
fluid in the tube now shows the quantity of acid in the must, by whole,
half and fourth parts per cent. The lines marked 1, 2, 3, 4, indicate
whole per cents.; the short intermediate lines, one-fourth per cents."

[Illustration: FIG. 33.]

When DR. GALL, shortly before the vintage of 1850, first publicly
recommended the dilution of the acids, he was obliged to refer to this
instrument, as already known, and everywhere at hand, which was at the
same time cheap, and simple in its use. "It is true, however, that if
must is examined by this instrument, the quantity of acids contained in
it, is really somewhat larger than indicated by the instrument; because
the acids contained in the must require for their saturation a weaker
solution of ammonia than acetic acid." As however, OTTO'S acidimeter
shows about one eighth of the acids less than the must actually
contains, and about as much acids combined with earths is removed
during fermentation, DR. GALL recommends that the quantity of acids be
reduced to 6-1/2, or at most 7 thousandths of OTTO'S acidimeter, and
the results have shown that this was about the right proportion; as the
wines in which the acids were thus diluted were in favor with all
consumers.

"The acidimeter referred to was afterwards improved, by making the tube
longer and more narrow, and dividing it into tenths of per cents,
instead of fourths; thus dividing the whole above 0 into thousandths.
But although by this improved acidimeter the quantity of acids could be
ascertained with more nicety, there remained one defect, that in often
turning the glass tube for mixing the fluids, some of the contents
adhered to the thumb in closing its mouth. This defect was remedied in
a new acidimeter, invented by Mr. GEISLER, who also invented the new
vaporimeter for the determination of the quantity of alcohol contained
in wine. It is based on the same principle as OTTO'S, but differs
altogether in