The adulteration of wine has been practiced from a very early date in those countries where the consumption is large. It has increased in amount and in the skillfulness of its practitioners until at the present day it requires for its detection all the knowledge and resources which chemical science can bring to bear upon it, and even then a large part doubtless escapes detection. It must be remembered, however, that in Europe the definition of adulteration has rather a wide scope, including the addition of substances which are simply diluents. The Paris Laboratory considers as a fraud "the addition of any substance for the purpose of gain which changes the composition of the natural wine." In Germany, on account of the northern situation of the country, it is permitted to the wine-growers in bad years, when the grapes contain a relatively high percentage of acid and a low percentage of sugar, to make use of pure sugar as an addition to the must, which addition is not considered as an offense against the adulteration laws, so long as the product is sold as "wine" simply. The amount of water added with the sugar must not be greater than twice the weight of the former, and the product must not be offered for sale as "natural wine."

By far the greater part of the adulteration carried on in the Euro-pean countries consists of this addition of water (mouillage) and sugar (sucrage). Such wines result from the methods of manufacture already described - petiotization, gallization, and chaptalization. For the detection of such wines it is necessary to establish maximum and minimum limits for the principal constituents of wines, and the relation in which these constituents stand to one another. To establish these limits is rather difficult, and requires a large series of analyses extending over many years. The constituents most relied on for the establishment of the character of a wine in judging whether it has been diluted or not are: the extract, content of free acid, and the relation between the extract and mineral matters.

In Germany the lowest limit of the extract in a natural wine is placed at 1.5 grams in 100cc, and after subtracting the amount of free fixed acids calculated as tartaric from the extract, the amount of the latter left must be not less than 1.1 grams; or after the subtraction of the total free acids as tartaric, not less than 1. gram in l00cc. In the Paris Laboratory no exact limits are set, the decision being left to the judgment of the analyst, after a careful comparison of the sample with analyses of previous similar wines done in the laboratory in past years. The sugar added is often glucose, which introduces into the wine substances more or less injurious, depending upon its character. Ordinary glucose contains usually 10 or 15 per cent. of non-fermentable substances, which serves to increase the weight of the extract, thus masking the addition of water. Its fermentation gives rise to the formation of a small quantity of amylic alcohol, which increases the intoxicating effect of such wines, and causes headache and nausea in those partaking of them.

In the detection of this substance advantage is taken of the non-fermentable character of the dextrin it contains, and of the presence of amylin, a non-fermentable, highly dextrorotatory body found in commercial starch sugar. 50cc. of wine, after driving off the alcohol by evaporation, are subjected to fermentation by the addition of a little well-washed yeast. After the fermentation is complete the liquid is clarified by means of lead or bone black, and polarized. If starch sugar has been used a strong rotation to the right will be observed, while if the wine was natural, or if the sugar used was cane sugar, there would be no rotation. The following procedure is also given by the German Commission :

Two hundred and ten cubic centimeters of the wine are evaporated to a thin sirup on the water-bath after the addition of a few drops of a 20 per cent. solution of acetate of potash. To the residue is gradually added with continual stirring 200cc. of 90 per cent. alcohol. The alcoholic solution when perfectly clear is poured off or filtered into a flask and the alcohol driven off until only about 5cc. remain. The residue is treated with about 15cc. water and a little bone-black, filtered into a graduated cylinder and washed with water until the volume measures 30cc. If, now, this liquid shows a rotation of more than +0.5, Wild, the wine contains the unfermentable matters of commercial potato sugar (amylin).

I have made no trial of these methods on American wines, and give them simply as a reference. It is well known that American starch sugar, made from corn, is quite different in composition from the European article, which is usually made from potato starch, and I do not know that the presence of amylin has been demonstrated in the American article. Whether the latter contains much dextrin or not depends upon the character of the "glucose" used; if it is the liquid glucose, I can testify from experience that it contains a considerable percentage of dextrin; but if it is the highly converted "grape sugar" or solid glucose that is used, probably not much dextrin is introduced into the wine from it.

Fraudulent wines are frequently made from raisins or dried grapes in France, and, according to French authorities, can easily be recognized by their high percentage of reducing sugar, and left-handed polarization after fermentation.

The plastering of wines, which is also very extensively carried on in France, consists in adding to the wine or must a large excess of gypsum, or sulphate of lime.

The sulphuric acid of the lime salt replaces the tartaric acid which is combined with potash, and forms an acid sulphate of potash, while the tartaric acid separates out as tartrate of lime. The operation is said to give the wine a brighter color and to enhance its keeping qualities, probably by a mechanical carrying down of some of the albuminous matters. Some authorities seem to regard the addition as a pardonable one on this account, but most condemn it. It certainly introduces into the wine a salt entirely foreign to the grape and of a more objectionable nature than that which it supplants, viz, the bitartrate of potash. Both Germany and France are in accord as to the limit of sulphuric acid which can be used in a wine, requiring a wine with a content of S03, corresponding to over 2 grams of potassic sulphate (K2 SO4) per liter, to be designated as a plastered wine. This figure affords a pretty wide margin, for the average content of wines, according to most observers, is not over one-fourth of the standard, or .5 grams K2 SO4 to the liter.