"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, should it be required, add another drop of the ammonia. Repeat this until the proper tone of color has been reached, neither red nor blue. After thus fixing the precise point of the saturation of the acids, the burette is held upright, and the quantity of the solution of ammonia consumed is accurately determined,--that is, to what line on the scale the burette has been emptied. The quantity of the solution so used corresponds with the quantity of acids contained in the must--the larger division lines opposite the numbers indicating the thousandths part, and the smaller lines or dots the ten thousandths part. "Until the eye has learned by practice to recognize the points of saturation by the tone of color, it can be proven by means of litmus paper. When the mixture in the bottle begins to turn blue, put in the end of a slip of litmus paper about half an inch deep, and then draw this end through your fingers, moistened with water. So long as the ends of the blue litmus paper become more or less reddened, the acids have not been completely saturated. Only when it remains blue, has the point of saturation been reached.