LOSS OF COLOUR IN WINE. 311 



was exempt from this decomposition. This view was left un con- 

 tradicted by BECHAMP (III.), although he had already ascribed 

 de-nitrification to the agency of micro-organisms. A closer in- 

 vestigation (embodying modern methods of working) of this nitric 

 fermentation of molasses is highly desirable. To be thoroughly 

 satisfactory, such research must trace the course followed by the 

 potassium nitrate in the juices of the sugar-works, and more 

 narrowly examine the quantitative dependence of the nitrate in 

 molasses on the method of preparation employed, very little being 

 as yet known on these points. 



The nitric decomposition in question is also of frequent occur- 

 rence in the fermentation of tobacco in heaps. SCHLOSING (III.) 

 reported in 1868 on the first observation made of this phenomenon 

 by Ch. Ray. 



174. The Loss of Colour (Umsehlagen, Breehen) 

 in Wine 



was first examined chemically by G. MULDER (II.) in 1855. Of 

 this complaint, which is known in France as vin tourne and in 

 Italy as vino girato, he gives the following explanation : " This 

 alteration of wine consists in a decomposition of the tartaric acid, 

 but how this decomposition is induced is unknown. The cream 

 of tartar is converted into potassium carbonate, whereby the colour 

 of red wine is altered and becomes brown. The decomposition 

 begins at the bottom of the cask, and is hence undoubtedly a result 

 of the decomposition of the organic matter of wine-yeast, which 

 contains a substance acting destructively on the tartaric acid, and, 

 in co-operation with air, oxidising it to carbon dioxide and water. 

 As the malady progresses, the alcohol is converted into acetic acid, 

 and a putrefactive fermentation ensues." The commencement 

 of this malady, which appears more frequently in red wines 

 than in white ones, manifests itself by a slight evolution of carbon 

 dioxide, which preliminary symptom is known in practice as "boil- 

 ing away" (versiederi). Tartaric acid is not the only substance 

 eliminated, glycerin also according to the researches of P. CARLES 

 (I.) being slowly decomposed. Simultaneously, the amount of 

 volatile acids increases to an unusual extent (up to 4 grams per 

 litre), a fact observed by SCHULTZ (I.), and afterwards confirmed 

 by J. MACAGNO (I.). 



Ten years after Mulder's observations, PASTEUR (XII.) undertook 

 the task of discovering the cause of this malady and proving that here 

 also the activity of a still unknown micro-organism was in question. 

 He showed that in wines affected with this complaint bacteria are 

 always detectable in large numbers, their length being 3-5 //., with 

 a breadth of 1-1.5 P" Greater probability was imparted to this 

 assumption by the observation made by SCHULTZ (I.), who, in 1877, 

 succeeded in artificially imparting the malady to sound wine by 



