"In examining _red_ must, the method should be modified as follows:--Instead of first filling the pipette with tincture of litmus, fill it with water to the line A, and transfer it into the bottle. After the quantity of must has been added, drop six-thousandths of the solution of ammonia into the mixture, constantly shaking it while dropping, then test it, and so on, until, after every further addition required with litmus paper, it is no longer reddened after having been wiped off." DR. GALL further gives the following directions, as a guide, to distinguish and determine the proportion of acids which a must should contain, to be still agreeable to the palate, and good: "Chemists distinguish the acid contained in the grape as the vinous, malic, grape, citric, tannic, gelatinous and para-citric acids. Whether all these are contained in the must, or which of them, is of small moment for us to know. For the practical wine-maker, it is sufficient to know, with full certainty, that, as the grape ripens, while the proportion of sugar increases, the quantity of acids continually diminishes; and hence, by leaving the grapes on the vines as long as possible, we have a double means of improving their products--the must or wine. "All wines, without exception, to be of good and of agreeable taste, must contain from 4-1/2 to 7 thousandths parts of free acids, and each must containing more than seven thousandths parts of free acids may be considered as having too little water and sugar in proportion to its quantity of acids. "In all wine-growing countries of Germany, for a number of years past, experience has proved that a corresponding addition of sugar and water is the means of converting the sourest must, not only into a good drinkable wine, but also into as good a wine as can be produced in favorable years, _except_ in that peculiar and delicate aroma found only in the must of well-ripened grapes, and which must and will always distinguish the wines made in the best seasons from those made in poor seasons. "The saccharometer and acidimeter, properly used, will give us the exact knowledge of what the must contains, and what it lacks; and we have the means at hand, by adding water, to reduce the acids to their proper proportion; and by adding sugar, to increase the amount of sugar the must should contain; in other words, we can change the poor must of indifferent seasons into the normal must of the best seasons in _everything_, _except_ its bouquet or aroma, thereby converting an unwholesome and disagreeable drink into an agreeable and healthy one." THE CHANGE OF THE MUST, BY FERMENTATION, INTO WINE.