350 



FERMENTATION 



fermentation of cane-sugar. ' Fifteen and a half pounds of refined sugar wcro dis- 

 solved in 10 gallons of water, making 10* gallons of solution, of which tho specific 

 gravity was 1055*3 at 60; and after adding thrco fluid pounds of frosli porter y. a-t, 

 tho specific gravity was 1055*95. Tho original gravity may be taken as 1055*3 

 (55*3). 



' Columns in. and v. respectively exhibit the spirit which has been produced, and 

 the solid matter which has disappeared ; the first in tho form of tho gravity of tho 

 spirit, expressed by the number of degrees it is lighter than water, or under 1000, 

 and the second by the fall in gravity of tho solution of the solid matter remaining 

 below the original gravity 1055*3. This last value will be spoken of as "degrees of 

 gravity lost;" it is always obtained by subtracting tho extract-gravity (column iv.) 

 from the known original gravity. To discover whether the progress of fermentation 

 has the regularity ascribed to it, it was necessary to observe whether tho same re- 

 lation always holds between tho columns of " degrees of spirit-indication " and " de- 

 grees of gravity lost." It was useful, with this view, to find what degrees lost 

 corresponded to whole numbers of degrees of spirit-indication. This can be donu 

 safely from the preceding table, by interpolation, where the numbers observed follow 

 each other so closely. The corresponding degrees of spirit-indication and of gravity 

 lost, as they appear in this experiment upon the fermentation of sugar, arc as follow: 



.TABLE III. Fermentation of Svgar-Wort of original gravity 1055*3. 



' In two other fermentations of cane-sugar, the degrees of gravity lost, found to 

 correspond to tho degrees of spirit-indication, never differed from tho numbers of the 

 preceding experiment, or from one another, more than 0*9 of gravity lost. This is a 

 sufficiently close approximation. 



' The following table is of much importance : 



TABLE IV. STARCH-SUGAR. 

 Degrees of Spirit-Indication, with corresponding degrees of gravity lost. 



Besides the degrees of gravity lost corresponding to whole degrees of spirit-indication, the degrees of 

 gravity lost corresponding to tenths of a degree of spirit-indication are added from calculation. 



' It is seen from this table that for 5 of spirit-indication, tho corresponding dcgn-cs 

 of gravity lost are 18*3. For 5*9 of spirit-indication, the corresponding degrees of 

 gravity lost are 22*2. 



'This table is capable of a valuable application, for tho sake of which it was con- 

 structed. By means of it, tho unknown original gravity of a fcrmonted liquid or beer 

 from cane-sugar may bo discovered, provided tho spirit -indication and extract- gravity 



