467 



Red wines thus affected appear sound whilst in the casks, 

 when air does not get at it, but without warning and almost sud 

 denly, when drawn or bottled, it turns black and shows a brownish 

 deposit. 



The taste and chemical constituents of the wine are not very 

 perceptibly altered, but the wines become unsightly. When looked 

 at through clear glass, either the white or red wine shows a scud, 

 and from brilliant and limpid when fresh drawn from the cask it 

 becomes dull, shows an irridescence on the surface, and the colour- 

 ing matter gradually oxidising throws a brown coloured sediment. 

 The wine sometimes has a leathery smell, and has a slightly acidu- 

 late and bitterish taste. 



The oxidising diastase feeding on the albuminoid substances in 

 the wine is more commonly met with in wines produced from grapes 

 grown on rich alluvial soils. Tannin, which coagulates albumen, is 

 generally deficient in such wines, and a slight addition of this sub- 

 stance is often attended with good results. Sulphur, however, is in 

 every case beneficial, and may be used at the rate of 6 to 30 

 grammes of sulphurous acid per 100 gallons, or its equivalent, three 

 to 15 grammes, of sulphur (Joz. to foz.), or 12 to 60 grammes (Joz. 

 to 2ozs.) of bisulphite of potash. 



Amongst the diseases caused by anaerobic microbes 



Mannitic Fermentation is one of the most troublesome in hot 

 climates. The cause of the disease are short, motionless, rod-like 

 microbes, which congregate in groups and are often found asso- 

 ciated with germs of other diseases. Two requirements are neces- 

 sary for its development the presence of unfermented sugar in the 

 wine, and a higher temperature than is suitable for the yeast 

 ferment, viz., 35-40 C. (95-104 F.). The disease generally starts 

 in the fermenting vat whenever the temperature is allowed to go 

 up too high. 



As a result of the presence of this microbe in large numbers, 

 the unfermented sugar is transformed into another kind of sugar, 

 called mannite, and into lactic acid, the result being a sour-sweet 

 wine. 



The remedies are low temperature fermentation, or early for- 

 tification with spirits of wine, or pasteurisation, 



The cream of tartar is not decomposed in inannitic wine, as is 

 the case in wines affected with the tourne disease. 



Tourne (Turning) and "Pousse" (Pushing) Diseases. These 

 diseases attack any kind of wine of low alcoholic strength. In 



