266 SCIENCE PROGRESS. 



dually the disturbance spreads to layers deeper and deeper 

 in the liquid, until at last the walls of the vessel are covered 

 by adherent matter, and the liquid is almost decolourised, 

 assuming a moderately characteristic yellow tint. The 

 deposits are formed of the colouring matter of the wine, 

 and are insoluble in solutions of tartaric acid, even if con- 

 centrated. The changes are not attended by any evolution 

 of gas. Bouffard says that such wines can be preserved 

 from this disorder by heating them to 6o° C. or by the 

 addition of traces of sulphurous acid. The change is not 

 due to bacterial action for it is not hindered by filtration 

 through porcelain, nor by the addition of reagents which 

 are fatal to microbes, such as salicylic acid or bichloride 

 of mercury. 



Gouirand (19) has shown that this change is due to 

 some principle which exists in the wine itself. He took 

 some samples of affected wine and after filtering a quan- 

 tity through porcelain a large addition of alcohol threw 

 down a precipitate of a flocculent character. When this 

 was collected and washed, a small quantity of it added 

 to sterilised sound wines very speedily produced the 

 disorder. This substance was destroyed by heating. In 

 some of Gouirand's experiments he treated samples of 

 sound wines with a small quantity of it, and dividing them 

 into two parts, he heated half to 8o° C. In periods varying 

 from twelve to seventy-two hours the disorder was pro- 

 nounced in the unheated samples, while the controls re- 

 mained clear and limpid indefinitely. Warming the controls 

 to 6o° C. gave variable results ; in some it inhibited the 

 action, in others it only slowed its progress. The substance 

 was not affected by heating to 50° C. 



When healthy wines were precipitated by alcohol in 

 the same way as the unsound ones, the precipitate had no 

 power of setting up the disorder when added to other 

 samples. 



Martinand has ascertained that this substance is present 

 in ripe grapes. An extract of these gives all the reactions 

 of laccase, oxidising hydroquinone, pyrogallol, etc., and 

 loses the power of producing these changes if heated to 



