Page:EB1911 - Volume 28.djvu/740

Rh another. The great epidemic in the French vineyards in the years 1882 to 1885 led to a reduction of the yield of about 50%. Many remedies for this disease have been suggested, including total submersion of the vineyards, the use of carbon bisulphide for spraying, and of copper salts, but there appears to be little doubt that a really serious epidemic can only be dealt with by systematic destruction of the vines, followed by replanting with resistant varieties. This, of course, naturally leads to the production of a wine somewhat different in character to that produced before the epidemic, but this difficulty may be overcome to some extent, as it was in the Bordeaux vineyards, by grafting ancient stock on the roots of new and resistant vines. Oidium or mildew is only second in importance to the phylloxera. It is caused by a species of mould which lives on the green part of the plant. The leaves shrivel, the plant ceases to grow, and the grapes that are formed also shrivel and die. The most effective cure, short of destruction and replantation, appears to be spraying with finely divided sulphur. Another evil, which is caused by unseasonable weather during and shortly after the flowering, is known as coulure. This causes the flowers, or at a later period the young fruit, to fall off the growing plant in large numbers.

Diseases of Wine.—These are numerous, and may be derived either directly from the vine, from an abnormal constitution of the grape juice, or to subsequent infection. Thus the disease known as tourne or casse is generally caused by the wine having been made or partly made from grapes affected by mildew. The micro-organism giving rise to this disease generally appears in the form of small jointed rods and tangled masses under the microscope. Wine which is affected by this disease loses its colour and flavour. The colour in the case of red wines is first altered from red to brown, and in bad cases disappears altogether, leaving an almost colourless solution. This disease is also caused by the wine lacking alcohol, acid and tannin, and to the presence of an excess of albuminous matters. The most common disease to which wine is subject by infection is that caused by a micro-organism termed mycoderma-vini (French fleurs de vin). This micro-organism, which resembles ordinary yeast cells in appearance, forms a pellicle on the surface of wine, particularly when the latter is exposed to the air more than it should be, and its development is favoured by lack of alcohol. The micro-organism splits up the alcohol of the wine and some of the other constituents, forming carbonic acid and water. This process indicates a very intensive form of oxidation inasmuch as no intermediary acid is formed. One of the most common diseases, namely that producing acetous fermentation, differs from the disease caused by M. vini in that the alcohol is transformed into acetic acid. It is caused by a microorganism termed Mycoderma aceti, which occurs in wine in small groups and chaplets of round cells. It is principally due to a lack of alcohol in the wine or to lack of acidity in the must. The micro-organism which causes the disease of bitterness (amer) forms longish branched filaments in the wine. Hand in hand with the development of a disagreeable bitter taste there is a precipitation of colouring matter and the formation of certain disagreeable secondary constituents. This disease is generally caused by infection and is favoured by a lack of alcohol, acid and tannin. Another disease which generally occurs only in white wines is that which converts the wine into a thick stringy liquid. It is the viscous or graisse disease. As a rule this disease is due to a lack of tannin (hence its more frequent occurrence in white wines). The mannitic disease, which is due to high temperatures during fermentation and lack of acid in the must, is rarely of serious consequence in temperate countries. The micro-organism splits up the laevulose in the must, forming mannitol and different acids, particularly volatile acid. The wine becomes turbid and acquires a peculiarly bitter sweet taste, and if the disease goes further becomes quite undrinkable. It would appear from the researches of the author and others that the mannitol ferment is more generally present in wines than is supposed to be the case. Thus the author found in some very old and fine wines very appreciable quantities of mannitol. In these cases the mannitic fermentation had obviously not developed to any extent, and small quantities of mannitol appear to exercise no prejudicial effect on flavour.

Treatment of Diseases.—It was found by Pasteur that by heating wine out of contact with air to about 66° C. the various germs causing wine maladies could be checked in their action or destroyed. The one disadvantage of this method is that unless very carefully applied the normal development of the wine may be seriously retarded. In the case of cheap wines or of wines which are already more or less mature, this is not a matter of any great importance, but in the case of the finer wines it may be a serious consideration. Pasteurizing alone, however, will only avail in cases where the disease has not gone beyond the initial stages, inasmuch as it cannot restore colour, taste or flavour where those have already been affected. In such cases, and also in others where pasteurizing is not applicable, some direct treatment with a view to eliminating or adding constituents which are in excess or lacking is indicated. In this regard it is somewhat difficult to draw the line between that which is a rational and scientific method for preventing waste of good material and sophistication pure and simple. It appears to the author, however, that where such methods are employed merely with a view to overcoming a specific malady and there is no intention of increasing

the quantity of the wine for purposes of gain, or of giving it a fictitious appearance of quality, these operations are perfectly justifiable and may be compared to the modifications of procedure which are forced upon the brewer or distiller who has to deal with somewhat abnormal raw material. It has been found, for instance, that in the case of the mannitic disease the action of the micro-organism may be checked, or prevented altogether, by bringing the acidity of the must up to a certain level by the addition of a small quantity of tartaric acid. Again, it is well known that in the case of the viscous disease the difficulty may be overcome by the addition of a small quantity of tannin. In the same way the disease caused by the mildew organism may be counteracted by a slight addition of alcohol and tannin. One method of assisting nature in wine-making, which is, in the opinion of the author, not justifiable if the resulting product is sold as wine or in such a manner as to indicate that it is natural wine, is the process termed “gallisizing,” so called from its inventor H. L. L. Gall, which has been largely practised, particularly on the Rhine. The process of Gall consists in adding sugar and water in sufficient quantity to establish the percentages of free acid and sugar which are characteristic of the best years in the must obtained in inferior years. Although there is no objection to this product from a purely hygienic point of view, it is not natural wine, and the products present in the must other than sugar and acid are by this process seriously affected. Another method of dealing with inferior must, due to J. A. C. Chaptal, consists in neutralizing excessive acid by means of powdered marble, and bringing up the sugar to normal proportions by adding appropriate amounts of this substance in a solid form. There is less objection to this process than to the former, inasmuch as it does not result in a dilution of the wine. It is scarcely necessary to say that the indiscriminate addition of alcohol and water, or of either to must or to wine, must be regarded as a reprehensible operation.

Plastering.—In some countries, particularly in Italy, Spain and Portugal, it has been and still is a common practice to add a small quantity of gypsum to the fermenting must or to dust it over the grapes prior to pressing. It is said that wines treated in this manner mature more quickly, and that they are more stable and of better colour. It certainly appears to be the case that musts which are plastered rarely suffer from abnormal fermentation, and that the wines which result very rarely turn acid. The main result of plastering is that the soluble tart rates in the wine are decomposed, forming insoluble tartrate of lime and soluble sulphate of potash. It is held that an excess of the latter is undesirable in wine, but unless the quantity appreciably exceeds two grams per litre, no reasonable objection can be raised.

Basis Wines.—Wines which are made not from fresh grape juice but from raisins or concentrated must, or similar material, are generally termed basis wines. They are prepared by adding water to the concentrated saccharine matter and subsequently pitching with wine yeast at an appropriate temperature. Frequently alcohol, tannin, glycerin, and similar wine constituents are also added. If carefully prepared there is no objection to these basis wines from a hygienic point of view, although they have not the delicate qualities and stimulating effects of natural wines; unfortunately, however, these wines have in the past been vended on a large scale in a manner calculated to deceive the consumer as to their real nature, but energetic measures, which have of late been taken in most countries affected by this trade, have done much to mitigate the evil.

It may be safely said that there is no other country in which the general conditions are so favourable for the production of wine of high quality and on a large scale as is the case in France. The climate is essentially of a moderate character; the winters are rarely very cold, and the summers are seldom of the intensely hot and dry nature which is characteristic of most southerly wine countries. There are large tracts of gently undulating or relatively flat country which is, inasmuch as it ensures effective exposal of the vines to the sun, of a type particularly suited to viticulture. There is almost everywhere an efficient supply of water, and lastly the character of the soil is in many parts an ideal one for the production of wine high in quality and abundant in quantity. It may here be stated that a rich soil such as is suitable for the growth of cereal crops or vegetables is not, as a rule, an ideal one for the production of fine wines. The ideal soil for vine-growing is that which possesses a sufficiency, but not an excess, of nutriment for the plant, and which is so constituted that it will afford good drainage. The most important qualification, however, is that it should be so constituted as to preserve and store up during the relatively cold weather the heat which it has derived from the atmosphere during the summer. In this respect the famous Bordeaux or Gironde district is, perhaps, more fortunate than any other part of the world. The thrifty and methodical