1896 THE MICROSCOPE. 19 



it does not form a scum but the greater part is deposited, 

 while the rest is mixed with the liquid. 



The best remedy for this grease is to add to each hec- 

 tolitre of the wine, from five to ten grammes of tannin 

 dissolved in alcohol, and after mixing thoroughly let it 

 settle for some time to form a good collage. 



The Bitter Infection. — This disease, which attacks 

 by preference the fine wines of Burgundy, shows itself 

 only when the wine is old. The wine at first loses its 

 flavor, then becomes bitter, and throws olf a peculiar 

 odor, the coloring matter is altered and forms a de- 

 posit. At this time the wine becomes undrinkable, but 

 as this change is only })roduce(l slowly, if it can be 

 arrested when the bitterness commences to manifest 

 itself, the wine may still be excellent. (Pasteur.) 



At the same time a bitter substance, which Mau- 

 mene thought to be aldehyde of ammonia, and which 

 other chemists believed to be citric ether, is formed in 

 quite large quantities from the carbonic acid. The 

 acidity of the wine increases, at least that part fur- 

 nished by the volatile acids, and in particular by the 

 etique acid and the hutyrate. 



The alteration is chiefly in the coloring matter and in 

 the tannin, and it also appears in the glycerine. 



The bitterness is due to a ferment discovered by Pas- 

 teur. In the deposit which forms in the diseased wine 

 numerous long and very slender sticks are found, These 

 sticks form articulated filaments; the articulations are 

 rigid and the branches irregular. The ferment is often 

 associated with crystals or w^ith little mammillated mas- 

 ses. It is generally impregnated with coloring matter 

 (fig. 2). One can, by treatment with alcohol or acid- 

 ulated water, carry off w^ith the ferment the foreign 

 matters which soil it. It then takes its original appear- 

 ance. 



When the bitterness first appears in a wine it can be 



