10 A Tribute to the Memory/ of 



The Essay on Ferments and Fermentation is valuable, not for 

 the theoretical speculations which it contains, for these have 

 been superseded by subsequent discoveries ; but for a few facts 

 of considerable importance. It was at that time believed that the 

 infusion of malt, called wort, could not be made to ferment, 

 without the addition of yeast, or barm ; but Mr. Henry discover- 

 ed that wort may be brought into a state of fermentation, by 

 being impregnated with carbonic acid gas. By a fermentation 

 thus excited, he obtained not only good beer, but yeast fit for 

 the making of bread ; and, from separate portions of the fer- 

 mented liquor, he procured also ardent spirit and vinegar, thus 

 proving that the fermentative process had been fully completed. 

 He found, moreover, that flour and water, boiled to the consist- 

 ence of a thin jelly, and impregnated with carbonic acid in a 

 Nooth's machine, passed into fermentation, and by the third day 

 had assumed the appearance of yeast, for which it served as a 

 tolerable substitute in the baking of bread. 



The other memoir, which is distinguished by its value and im- 

 portance, is entitled, " Considerations relative to the Nature of 

 Wool, Silk, and Cotton, as Objects of the Art of Dyeing; on the 

 various Preparations and Mordants requisite for these different 



Mode of exciting Fermentation in Malt Liquors, without the aid of Yeast, 

 is pointed out ; with an attempt to form a new Theory of that Process. 



(3.) Observations on the Influence of Fixed Air on Vegetation, and on 

 the probable Cause of the DifiFerence in the Results of various Elxpe- 

 riments made for that purpose. 



lu Vol. III. Observations on the Bills of Mortality for the Towns of Man- 

 chester and Salford. 



(2.) Case of a Person becoming short-sighted in Advanced Age. 



(3.) Considerations relative to the Nature of Wool, Silk, and Cotton, as 

 Objects of the Art of Dyeing ; on the various Preparations and Mor- 

 dants requisite for these different substances ; and on the Nature and 

 Properties of Colouring Matter — Together with some observations on 

 the Theory of Dyeing in general, and particularly the Turkey-Red. 



New Series, Vol. II. Remarks on Mr. Nicholson's Account of the Effects 

 produced at Swinton by a stroke of Lightning. 



And a Paper, printed in this volume, entitled. Memoirs of the late Charles 

 White, Escj. F.R.S,, chiefly with a Reference to his Professional Life and 

 Writings. 



