Generally described, these consist in producing an imitation of the natural salinity of the dry wine by the addition of factitious salts and fortifying with alcohol. The sugar remains, but is disguised thereby. It was a wine thus treated that first brought the subject of the sulphates, already referred to, under my notice. This, although sold to my friend at a good price, was a concoction of the character known in the trade as Hambro' sherry. It contained a considerable quantity of sugar, but was not perceptibly sweet. It was very strong and decidedly acid; contained free sulphuric acid and alum, which, as all who have tasted it know, gives a peculiar sense of dryness to the palate.
The sulphuring, plastering, and use of Spanish earth, described in my last, increase the dryness of a given wine by adding mineral acid, and mineral salts. In a paper recently read before the French Academy by L. Magnier de la Source ("Comptes Rendus," vol. xcviii, page 110), the author states that "plastering modifies the chemical characters of the coloring-matter of the wine, and not only does the calcium sulphate decompose the potassium hydrogen tartrate, with formation of calcium tartrate, potassium sulphate, and free tartaric acid, but it also decomposes the neutral organic compounds of potassium which exist in the juice of the grape." I quote from abstract in "Journal of of the Chemical Society" of May, 1884.
In the French "Journal of Pharmaceutical Chemistry," vol. vi, pp. 118-123 (1882), is another paper, by P. Carles, in which the chemical and hygienic results of plastering are discussed. His general conclusion is that the use of gypsum in clearing wines "renders them hurtful as beverages"; that the gypsum acts "on the potassium bitartrate in the juice of the grape, forming calcium tartrate, tartaric acid, and potassium sulphate, a large proportion of the last two bodies remaining in the wine." Unplastered wines contain about two grammes of free acid per litre; after plastering, they contain "double or treble that amount, and even more."
A German chemist, Griessmayer, and, more recently, another. Kaiser, have also studied this subject, and arrive at similar conclusions. Kaiser analyzed wines which were plastered by adding gypsum to the must, that is to the juice before fermentation, and also samples in which the gypsum was added to the "finished wine," i. e., for fining, so called. He found that "in the finished wine, by the addition of gypsum, the tartaric acid is replaced by sulphuric acid, and there is a perceptible increase in the calcium; the other constituents remain unaltered." His conclusion is, that the plastering of wine should be called adulteration, and treated accordingly, on the ground that the article in question is thereby deprived of its characteristic constituents, and others, not normally present, are introduced. This refers more especially to the plastering or gypsum fining of finished wines (Biedermann's "Centralblatt," 1881, pp. 632, 633).
In the paper above named, by P. Carles, we are told that, "owing
