─────────────────────────────────────────────────┬───────────────────── │ Glucose. │ ┌────────────── │ │ Mannose. │ │ ┌───────── │ │ │Fructose. ─────────────────────────────────────────────────┼──────┼────┴───────── Maximum rate attained, c.cs. per five minutes │ 9·6 │ 7 11·3 Final rate of fermentation │ 1·1 │ 0·96 1·08 Total carbon dioxide produced by fermentation in │ │ fifty-five minutes after addition of phosphate│ 49·7 │ 47·8 47·6 Correction for evolution in absence of phosphate │ │ in fifty-five minutes │ 12·1 │ 10·6 11·9 Extra carbon dioxide equivalent to phosphate │ 37·6 │ 37·2 35·7 " " " " " " at N.T.P.│ 34·4 │ 34 32·6 ─────────────────────────────────────────────────┴──────┴────────────── These numbers agree well with the value calculated from the phosphate added, viz. 32·6 [Harden and Young, 1909]. Another experiment is illustrated graphically in Fig. 4, in which the volume of carbon dioxide evolved is plotted against time. The determination was in this case made by adding 25 c.c. of an aqueous solution containing 5 grams of glucose to one quantity of 25 c.c. of yeast-juice (curve A) and 5 c.c. of 0·3 molar solution of the mixed primary and secondary sodium phosphates, and 20 c.c. of a solution containing 5 grams of glucose to a second equal quantity of yeast-juice (curve B). Curve A shows the normal course of fermentation of yeast-juice with glucose. There is a slight preliminary acceleration during the first twenty minutes, due to free phosphate in the juice, and the rate then becomes steady at about 1·4 c.c. in five minutes. During this preliminary acceleration 10 c.c. of extra carbon dioxide are evolved, this number being obtained graphically by continuing the line of steady rate back to the axis of zero time. Curve B shows the effect of the added phosphate. The rate rises to about 9·5 c.c. in five minutes, i.e. to more than six times the normal rate, and then gradually falls until after an hour it is again steady and almost exactly equal to 1·4 c.c. per five minutes. Continuing the line of steady rate back to the axis of zero [p045] time it is found that the extra amount of carbon dioxide is 48 c.c. Subtracting from this the 10 c.c. shown in curve A as due to the juice alone, a difference of 38 c.c. is obtained due to the added phosphate. The amount calculated from the phosphate added in this case is, at atmospheric temperature and pressure, 38·9 c.c. [Illustration: FIG. 4 (Graph of Carbon Dioxide Evolution v Time--Ed.)]