310 PHENOMENA OF PUTREFACTION. 



extends to the formation of ammonia. Several investigations on 

 this point were made by 0. LOEW (III.), but, unfortunately, not 

 with pure cultures. He found that "ordinary putrefactive bac- 

 teria," grown in a solution of i per cent, of peptone, 0.2 per cent, 

 of KNO 3 , and 0.2 per cent, of K 2 HP0 4 , cause the potash and 

 carbon dioxide to combine, whereas the nitrogen of the nitric acid 

 is converted into ammonium carbonate. When 0.2 per cent, of 

 ethyl alcohol is also present (in anaerobic cultures) the acetate is 

 formed instead of the carbonate. 



What has already been detailed will explain the so-called nitric 

 fermentation of molasses. The cell sap of the sugar-beet con- 

 tains a quantity generally small, but occasionally larger of 

 nitrates, principally potassium nitrate. This is not separated 

 during the saturation process, but remains in the mass in un- 

 diminished quantity, a portion crystallising out, and being then 

 found in the raw sugar from the centrifugal machine, whilst the 

 rest remains in the mother liquor, i.e. the separated syrup. If this 

 syrup is then boiled up for the manufacture of second product, 

 and again passed through the centrifugal machine, the proportion 

 of nitrates in the mass will be still larger, Pellet having found 

 1.9 per cent, of KN0 3 in one sample examined by him. At this 

 stage the molasses has a faintly alkaline reaction, and is rich in 

 organic and inorganic nutrient substances of various kinds. Hence 

 it is no wonder if bacteria rapidly develop therein. Under special 

 conditions the upper hand is gained by such organisms as reduce 

 potassium nitrate and eject its nitrogen in the form of NO, which 

 compound, on coming in contact with air, is oxidised into the 

 dioxide N0 2 . The latter hangs as a dense red-brown vapour 

 over the surface of the molasses, and the sugar-maker then says his 

 molasses is in a state of nitric fermentation. This phenomenon is 

 of less frequent occurrence in the "reserves" in the sugar-fac- 

 tories than in the dilute molasses of the molasses distilleries. 

 Certainly, the activity of these reducing bacteria can be arrested 

 by souring, but this treatment liberates organic acids inimical to 

 the yeast. Bearing this in mind, Czeczetka proposed to remedy 

 the evil by boiling the molasses directly the malady is observed. 

 According to a report by DUBRUNFAUT (I.) in 1868, nitric fer- 

 mentation was first noticed by Tilloy at his distillery in Dijon, 

 and was successfully suppressed by him by boiling the molasses 

 along with sulphuric acid. An explanation (characteristic of the 

 state of knowledge in the domain of Fermentation Physiology at 

 that time) of the favourable influence of this treatment was made 

 in the same year by J. REISET (II.), who stated that the NO or 

 NOo formed during the so-called nitric fermentation proceeds from 

 the oxidation of ammonia in the molasses, this being attacked 

 only when present in combination with a weak acid, whilst when 

 in the form of sulphate it resists the action of oxygen; conse- 

 quently the molasses treated in the manner adopted by Tilloy 



