a) The simple destruction of acidity by the agency of bacteria, without the production of volatile acids or other unfavourable by-products. is not to be considered as a disease of wines, since it increases the value of wines very rich in acids. It is just on this kind of destruction of acidity that very few data are found in the works of French investigators; they speak of tourne" and " pousse" and mean by these terms a morbid alteration of wines. While according to the writers "pousse " implies several alterations of wine caused by bacteria and accompanied by the formation of carbonic acid. This pousse can appear together with the simple destruction of acidity, with the formation of lactic acid and with tourne." Under "tourne the writers understand only the consequences. of the destruction of acidity in wines that are poor in acids. " " The destruction of acidity is not caused by ferments but by bacteria, namely Bacterium gracile or species of Microccus (Micrococcus malolacticus Seifert, M. acidovorax and M. variococcus). Cool cellarage, early racking from the lees, the addition of potassium metasulphite to the wine or the fumes of burning sulphur delay the destruction of acidity, which can also be prevented by the addition of acids. Malic acid as an addition is too expensive; besides, some bacteria destroy this acid also, as well as citric acid. As the most suitable the writers recommend tartaric acid. Tannin also reduces the destruction of acidity. Fining cannot be considered as an efficient remedy, as it does not rid the wine of the bacteria which cause the mischief. Where a diminution of acidity is desirable, it can be favoured by the omission of some of the above-mentioned preventive processes. Whether the reduction of acidity may be promoted by the addition of cultures of bacteria must be ascertained by further experiments. b) Acidity due to lactic acid occurs in fruit wines that are deficient in acidity and in mild grape wines; it is detected by a sour sweetish, somewhat acid taste and an odour recalling sauerkraut. The principal symptom of sourness due to lactic acid is the decomposition of sugar, accompanied by the production of lactic acid and much volatile acid. With this, as a rule, the destruction of malic acid and frequently a mannitic fermentation are connected, though the quantity of mannite that is formed depends essentially upon the temperature and upon the extent to which alcoholic fermentation had proceeded when the disease made its appearance. In French literature no special term is found for the sourness due to lactic acid, it being considered by French investigators together with mannitic fermentation and tourne." The writers consider the sourness due to lactic acid and mannitic fermentation as two distinct diseases, with the reserve that with the latter the former is always connected, while lactic acid sourness can appear alone. In the writers' experiments, Bacterium mannitopeum was almost always the cause of lactic acid sourness; only exceptionally could it be attributed to Bacterium gracile. A high content of acidity or of tannin or a moderate amount of both together can prevent lactic acid sourness. Very low temperature during fermentation can also act as a preventive, though with low acid and tannin content even a slight degree of warmth is sufficient to originate lactic acid sourness. Early racking from the lees is a preventive of the disease when it is connected with an average acid and tannin content and moderate temperature. It behaves similarly with the use of sulphurous acid. The employment of pure ferments is also a protection to a certain extent against lactic acid sourness. c) The "mousiness" (smell and laste of acetamide) according to experiments by the writers, appears to be due to Bacterium mannitopeum. These bacteria multiply chiefly in liquids containing sugar; consequently this taste appears in refermented wines to which sugar solutions have been added. d) The turning ("tourne") of wines has already been mentioned above. The writers abstain from giving a definition of this direase, as their investigations on it are not yet sufficiently advanced. They do not affirm that turning is always a consequence of the destruction of acidity, but they conclude from the results of their investigations on diseased wines that the two phenomena are intimately connected. In Chapter V the writers give advice on the analyses of wines, and recommend not only the determination of the amount of lactic acid but also investigation of its origin by means of bacteriological examination. It is true that all the bacteria that the writers describe are producers of lactic acid, but their power of producing this acid is various. Wines containing only small quantities of lactic acid and of volatile acids are generally sound. In wines containing much lactic acid and little volatile acids a destruction of acidity has, as a rule, taken place. Examination under the microscope can reveal what kind of bacteria have taken part in the process; most frequently Bacterium gracile will be found to have been the cause, though cocci can also be found. Wines contain but little lactic acid and much volatile acidity when, owing to improper handling, they have contracted acetic sourness. As mould ferments also produce volatile acids they also can be taken into consideration. In both cases investigation under the microscope throws light on the origin of the volatile acids. If more than I per thousand of lactic acid is found, it is to be assumed that this is due to acid-destroying bacteria or to the transformation of sugar caused by bacteria. Much lactic acid and much volatile acid (2 to 3 per thousand) appear with lactic acid sourness. As causes, Bacterium mannitopeum, the mannite ferment of Gayon and Dubourg, and exceptionally also Bacterium gracile may be considered. The first two are easily revealed by the microscope. If Bacterium gracile is the cause, the presence of mannite in the wine can be shown by microscopical investigation. If Bacterium gracile has only destroyed acidity and formed lactic acid, while acetic acid bacteria have formed acetic acid, no mannite will be found. When much lactic acid and much acetic acid are present and the latter prevails, most frequently it is a case of lactic acid sourness connected with acetic acid sourness. - 308 The Acidification of Musts by the Action of Yeast during Alcoholic Fermentation. FERNBACH, A. L'acidification des moûts par la levure au cours de la fermentation alcoo lique. Revue de Viticulture, Year 20, Vol. XXXIX, No. 997, pp. 113-114. Paris, January 23, 1913. All liquids containing sugar, when submitted to alcoholic fermentation, undergo during the process an increase in acidity due, in a slight measure, to the production of succinic acid, but chiefly to the formation of volatile acids (acetic acid predominates always, and sometimes is the only volatile acid formed). Numerous different species of yeast are clearly distinguishable by the nature and the proportion of the volatile acids they produce in a given medium. The experiments of which the results are given later, were undertaken for the purpose of ascertaining how the acidification of the fermenting liquid varies in the use of the same yeast, according to different influences, and particularly in order to discover if this variation is due to the influence of the reaction of the medium. To this end, the writer sowed a number of cells of the same species of yeast in a series of flasks containing the same sugary liquid, either artificial or natural (grape must), adding increasing amounts of tartaric acid varying from o to 8 gr. per litre. In the different flasks of the same series, he determined at the same time whether the fermentation had been completed or not, the acidity of the liquid, the amount of sugar remaining, the alcohol produced and the weight of yeast formed. The following are the figures obtained in the course of some of the writer's experiments, giving the increase in acidity expressed everywhere, as is the original acidity, in mg. of total tartaric acid : It is seen that, in all these cases, the less acid the liquid was at first, the greater the subsequent increase in acidity. Thus the various yeasts are affected in the acidification which they produce, by the influence of the medium in which they act, quite independently of their own individual characteristics. This conclusion is of great importance from the practical standpoint. Acidification has of late been rightly regarded as a means of increasing the stability of fermented beverages, and it has been strongly recommended that those yeasts which give rise to the highest degree of acidity should be selected. It is evident that the influence exerted upon this acidification by the original acidity of the must should be taken into account. The above mentioned facts show that this matter is no less important theoretically, for the study of the mechanism of alcoholic fermentation. Indeed they furnish a practical means of increasing acid production by yeast, and the writer hopes to show shortly how this method can be employed in the study of the intermediate products of fermentation. 309 Analytical Characters of the 1912 Musts in the Canton of Vaud, Switzerland. PORCHET, F. and TONDUZ, P. Moûts vaudois 1912. Procès-Verbaux de la Société Vaudoise des Sciences naturelles, No. 2, 1913 (meeting of January 8). Lausanne, January 1913. This article gives a summary of the analytical statistics of the musts of Vaud in 1912 (1). The analyses dealt with 137 samples. The dry cold weather, which on October 16 encouraged optimism, was unfortunately of very short duration, for on the 21st rain fell once more. This new damp period produced a decrease in quantity and quality—a rare occurrence — causing the ripe grapes to rot, while the less ripe ones remained unharmed. In spite of this, the predictions were realized in so far that the sugar content of the 1912 musts was, on the average, very similar to that of those of 1911. The following table shows the difference in this respect between the musts of 1912 and the wines of 1911. OTHER INDUSTRIES DEPENDING ON PLANT PRODUCTS As is shown by these figures, the average alcohol content of the 1912 wines in two of the districts is superior to that of the wines of 1911, while in the three other districts it is inferior; the differences vary between +0.5 per cent. and 0.9 per cent. Acid content. -The season of 1911 produced wines in the Canton of Vaud which were abnormally deficient in acids, while those of 1912 had a very high acid content. The figures have not yet been generally recorded, but the statement refers not only to the Swiss vineyards, but also to those of the rest of Europe, with the exception of the southern parts of Italy and of Spain. The acidity of the musts from Vaud which were analysed varied from 9.8 gr. to 16.4 gr. per litre; in the greater number of the samples, it was between II and 13 gr. per litre. It is an interesting scientific fact, which has been recorded fairly regularly, that when the fruit ripens with difficulty, the acidity is due essentially to malic acid and not to tartaric acid or acid salts. Usually the malic acid in wines is split up by the action of a micrococcus into lactic acid and carbonic acid. This causes a decrease in the acidity independently of the settling of the tartrates. At the end of January 1913, this malo-lactic decrease was not yet perceptible in the 1912 Champ-de-l'Air wine, though it contains 6.3 gr. of malic acid out of a total acid content of 13.6 gr. per litre. 310 New Materials for Paper-Making. I. - New Sources of Paper (Hedychium coronarium Koen and Allies). Royal Botanic 2 3. Marram Grass for Paper-making. — Ibid., p. 396. Experiments with New Materials for the Manufacture of Paper. Bulletin of the Imperial Institute, Vol. X, No. 3, pp. 372-380. London, 1912. I. — Hedychium coronarium (Zingiberaceae) is a native of India, being distributed from the Himalayas to Ceylon and Malacca; it is also recorded from Central America, the West Indies, Mauritius and West Africa (Corisco Bay). In some of the States of Brazil it has run wild, being especially abundant at Morrettes in the State of Parana, where it has covered a large tract of swampy country. In Brazil, the plant grows |