36 ON THE POISONOUS ACTION OF DI-CYANOGEN. 
ment of bacterial vegetation was seen in the control flask, while 
in the flask of hydrocyanic acid solution a slight incipient 
turbidity indicated a beginning of vegetation, and in the case 
of cyanogen the liquid remained entirely clear and unchanged. 
Several other experiments have been made in a dilution of 1 : 5000 
and i : 3000, and in each case the poisonous action of the two 
substances upon bacteria was clearly observed. 
In another experiment, 1 gram of peptone was dissolved at 
ordinary temperature in 100 c.c. of a 1 : 1000 solution of hydro¬ 
cyanic acid. After filtration, it was infected from putrid meat. 
At the same time, 1% solution of peptone was infected from the 
same source. After standing five days the latter solution showed 
a putrid smell, and white flocculent masses consisting of numer¬ 
ous bacteria, while in the first case no trace of turbidity or of 
putrid smell could be observed and no bacteria were found on 
examining under a microscope. 
In a further experiment, 1:1000 solutions of di-cyanogen and 
hydrocyanic acid containing 1% of kreatin, 0.1% of di-potassium 
phosphate and a drop of a 10% solution of magnesium sulphate 
were infected from a vegetable matter in lactic fermentation. 
After standing a fortnight in closed vessels at ordinary temper¬ 
ature, these liquids 1 ) were perfectly clear and free from bac¬ 
teria, 2 ) while the control solution showed a strong development. 
The poisonous action of hydrocyanic acid for bacteria was 
also proved by the observation of Liebig, 1 2 3) that blood does not 
undergo putrefaction for a considerable time, when 1/1000 of its 
weight hydrocyanic acid is added. He also observed, that yeast- 
water did not putrefy when some hydrocyanic acid was added 
to it. 
Action of Di-cyanogen and Hydrocyanic Acid 
upon yeast Cells. 
Some thick yeast 4) obtained fresh from a brewery was 
mixed with a di-cyanogen solution of 1 : 2500 and after frequent 
1) At that time the di-cyanogen and prussic acid remained unchanged and were 
perceptible by smell. 
2) According to E Schaer the development of mould fungi can be prevented by 
hydrocyanic acid in a dilution of i : ioooo (Zeit. f. Biologie 1870, Bd. 6, S. 509.) 
3) Ann. der Chemie u. Pharmacie 1870, Bd. 153, S. 137 etc. 
4) The yeast-mass of the size of a pea corresponding to in average 0.07—o. 1 grams 
dry matter was shaken with 50 c.c. of the solution. 
