368 
Messrs Purvis and Wilks, The influence 
dark = 13*6 c.c. 
white =14 -4 „ 
red = 14-5 „ 
blue =31 ’35 „ 
In this IV. series, a small leak was noticed in the cell containing 
the blue solution, so that a little of the copper sulphate was mixed 
with the wort. The copper sulphate appeared to inhibit the 
action of the yeast very greatly as is seen from the optical activity 
numbers. The bacteria, however, were not affected to the same 
extent, for the acidity in the blue instead of being less than in the 
others was more than twice as great. The increased amount of 
acid would attack the copper vessel, the development of the yeast 
would be inhibited to a greater extent than the bacteria, and 
consequently the acidity would be greatly increased. 
But the general results and the effects are comparable with 
those of the wort II. They were both rich worts. 
V. The unfermented wort gave the following analysis. 
Optical activity for 100 °/ 0 solution = + 11 43°. 
The copper oxide reducing power and the nitrogen content 
were not determined. 
The wort was pitched on May 23 at 4 p.m. and the temperature 
was 21°. And in addition to the four fermentations in the copper 
vessels, there was also an additional fermentation in a glass beaker 
under the influence of white light. The average temperatures 
between May 23 at 5.30 p.m. and May 28 at 9 a.m., were : 
dark = 24‘4° C. 
white =24-7 „ 
red = 24-7 „ 
blue = 24-9 „ 
white (beaker) = 24-7 „ 
The following are the results of the analyses of the fermenta- 
tions : 
(1) Optical activity for 100 °/ D solutions at 15° C. 
dark = + 5-15° 
white = + 5T0 
red = + 5-00 
blue = + 543 
(2) Specific gravity : 
dark = 991 ‘43 
white = 991-82 
red = 99T34 
blue =991-19 
N 
(3) Acidity. The numbers represent the amounts of — 
