This was contained in a narrow-necked litre flask fitted with a rubber stopper, and narrow delivery tube dipping under mercury, and sterilised with all the usual precautions. The fermentation began on the second day, reached its height from the 6th–8th day, and continued for 39 days, when gas ceased to come off. The examination of the gases will be described later on. When the fermentation was over, the liquid was brought to boiling temperature. It was then examined for the volatile acids in exactly the same manner as we described in our previous paper.

140 c.c. normal HCl was added and distillation commenced; the distillate was acid. The distillation was continued until the distillate ceased to be acid, forming fraction I. Three more fractions were now distilled off using respectively 10, 20, and 17 c.c. N1HCl.

The fractions were boiled with excess of BaCO3 filtered, the BaCO3 washed with hot water, the filtrate evaporated to dryness, and the barium salts dried at 130° C. till the weight was constant.[177] The salts were then decomposed with strong H2SO4, ignited, and the barium sulphate weighed. The following is a tabulated statement of the results:—

Fraction

Weight of
Salts

Weight of
BaSO4

Per Cent. of
BaSO4

I.

 1·24201·091587·88

II.

0·99150·917092·49

III.

 1·21551·198098·56

IV.

0·63500·623098·11

Calculating fraction I. as a mixture of barium acetate and butyrate, and fractions II., III., and IV. as mixtures of barium acetate and formate,[178] we get:—

Fraction

Weight of
Salts

Ba
Butyrate

Ba
Acetate

Ba
Formate

I.

 1·24200·26300·9790

..

II.

0·99151

..

0·893300·0982

III.

0·2155

..

0·440000·7755

IV.

0·6350

..

0·25520·3798
  Totals4·08400·26302·5675 1·2535

Calculating the barium salts into their respective acids we get:—

Fraction

Formic Acid

Acetic Acid

Butyric Acid

I.

..

0·460700·1488

II.

0·039800·42040

..

III.

0·31430·20710

..

IV.

0·15390·1201

..

  Totals0·5080 1·20830·1488