its construction. It is composed of three parts, all made
of glass; the mixing bottle, Fig. 34; the Pipette, Fig. 35; and the
burette, Fig 36. Besides, there should be ready three small
glasses--one filled with tincture of litmus, the second with a solution
of 1,369 per ammonia, and the third with the must or wine to be tested;
also, a taller glass, or vessel, having its bottom covered with cotton,
in which glass the burette, after it has been filled with the solution
of ammonia, is to be placed in an upright position until wanted.

[Illustration: FIG. 34.]

[Illustration: FIG. 35.]

[Illustration: FIG. 36.]

"To use this instrument the must and the tincture of litmus, having
first received the normal temperature of 14 deg. Reaumer, are brought into
the mixing bottle by means of the pipette, which is a hollow tube of
glass, open on both ends. To fill it, place its lower end into the
tincture or must, apply the mouth to the upper end, and by means of
suction fill it with the tincture of litmus to above the line indicated
at A. The opening of the top is then quickly closed with the thumb; by
alternately raising the thumb, and pressing it down again, so much of
the tincture is then allowed to flow back into the glass so as to lower
the fluid to the line indicated at A. The remainder is then brought
into the bottle, and the last drops forced out by blowing into the
pipette.

"In filling it with must, raise the fluid in the same way, until it
comes up to the line indicated at B, and then empty into the mixing
bottle.

"The burette consists of two hollow tubes of glass. In filling it, hold
the smaller tube with the right hand into the glass containing the
solution of ammonia, apply the mouth to the larger one, and by drawing
in the fluid the tube is filled exactly to the line indicated at 0 of
the tube.

"Holding the mixing bottle by the neck between the thumb and forefinger
of the left hand, place the smaller tube of the burette into the mouth
of the mixing bottle, which must be constantly shaken; let enough of
the solution of ammonia be brought drop by drop, into the mixture in
the bottle, till the red has been changed into the deep reddish blue of
the purple onion. This is the sign of the proper saturation of the
acids. To distinguish still better, turn the mixing bottle upside down,
by closing its mouth with the thumb, and examine the color of the fluid
in the tube-shaped neck of the bottle, and afterwards, shou