of light and of copper on fermentation. 
367 
IV. The following is the analysis of the unfermented wort. 
Optical activity for 100 °/ 0 solution = + 28"6°. 
Copper oxide reducing power in 20 c.c. of a 20 °/ 0 solution = 
1052 gm Cu. 
N 
The nitrogen content ; 25 c.c. of — H 2 S0 4 were used and 
N 
13*5 c.c. — NaHO were required to neutralise the excess after 
10 
Kjeldahling. 
The wort was pitched on May 13 at 5 p.m., and the average 
temperatures between May 14 at 9 a.m. and May 20 at 9 a.m. 
were : 
dark =23-4° C. 
white =23-6 „ 
red = 23-4 „ 
blue = 23-3 ,, 
The following gives the results of the analyses of the various 
fermentations : 
(1) Optical activity for 100 °/ 0 solutions at 15° C. 
dark = + 5-97° 
white = + 4-60 
red = + 4 - 93 
blue = + 8-08 
(2) Copper oxide reducing power in 20 c.c. of 20 °/ Q solutions: 
dark = 0-217 gm. Cu. 
white = 0T48 „ 
red =0T59 ,, 
(3) Specific gravity : 
dark = 987 '80 
white = 987'38 
red = 987-38 
(4) The nitrogen content; the numbers represent the c.c. of 
N 
IQ NaHO required to neutralise excess of acid after the distillation 
of the NHo by the Kjeldahl process : 
dark = 17 ’07 c.c. 
white =17 '92 „ 
red =17-70 „ 
(5) The acidity. The following numbers represent the 
N 
amounts of alkali used to neutralise 50 c.c. of each of the 
fermentations : 
