1 88 CHEMISTRY OF THE YEAST CELL. 



perty of settling down in granular aggregations when fermenta- 

 tion is completed, so that the whole of the yeast separates 

 completely when the bottle is degorged. Now, many of the 

 yeasts present in the wine itself are incapable of fulfilling this 

 last requirement, and for this reason waste has hitherto been 

 inevitable. The yeast refuses to " shake on to the cork " in a 

 satisfactory manner, i.e. it cannot be induced to rest in position 

 above the cork by the usual process of carefully tapping and 

 turning the inverted bottles, but adheres in patches on the walls 

 and cannot be dislodged : thus making the champagne of inferior 

 value, or even quite unsaleable. However, thanks to the en- 

 deavours of H. Mueller-Thurgau (IV. and Y.) and J. Woet- 

 MANN (Y.), champagne manufacturers are now able to obtain 

 pure yeasts which will shake on to the cork properly, and collect 

 as a gravelly deposit without adhering to the sides of the bottle. 

 The removal of the yeast is therefore attended with far less 

 waste of liquor than was formerly the case ; and the same may 

 also be reduced to a minimum by means of the process patented 

 in Germany (No. 60,351) by Walfard. In this method the 

 granular deposit of yeast is congealed by immersing the corked 

 bottles in a refrigerating mixture at a temperature of about 

 - 20° 0. ; on the bottle being then set upinght, the yeast and 

 cork (which has contracted under the influence of the cold) are 

 easily expelled together by the immediately augmented pressure 

 of the carbon dioxide. 



The highest demands on the coherence of the yeast colonies 

 are made on the stocks used for the purposes of the sparkling 

 fermentation introduced into practice by H. Mueller-Thurgau 

 (Y.). In order to increase the stimulative effect on the con- 

 sumer's palate, it has become more and more the custom of late 

 years to make thinner grape and fruit wines, poorer in flavour- 

 ing extractive substances but rich in carbon dioxide or 

 " sparkling." This enables one to dispense with the artificial 

 enrichment with carbon dioxide (carbonation) already extensively 

 practised (according to Nessler (III.)) in the Moselle district, 

 sparkling fermentation being a more efiicient substitute therefor. 

 The clear or clarified wine, which has either been poor in gas 

 from the outset or has become flat through repeated rackings, 

 is treated with an addition of 300 to 500 grams of saccharose 

 per hectolitre, and the whole is then pitched with a pure yeast 

 that remains at the bottom throughout the entire period of gas 

 formation, which soon begins. Contrary to what happens during 

 fermentation in champagne bottles, the fermenting liquid retains 

 its brilliance undiminished all the time, and Avhen finally matured 

 and sparkling can be readily and effectually separated from the 

 settled ferments. Reihlen, of Stuttgart, many years previously 

 ai'rived at the same result by different means, namely, by the 

 use of what he termed " fettered " yeast, prepared by impreg- 



