608 REPORT— 1894. 



Solid caustic soda is also very soluble in the melted base ; care must be taken 

 to keep it cool when adding the soda. This solution is much more liable to oxida- 

 tion than the free base ; exposed to the air the solution may spontaneouslj' inflame. 

 So we see that the presence of alkali (or rather of NaONH„) increases in a hiprh 

 degree the liability to oxidation, the free base oxidising not so quickly as the solu- 

 tion of NaOH in it, while the solid NaONFTj explodes in contact with the air. 



Although, as has been shown, free hydroxylaraine is a strong reducing agent, 

 it can be reduced itself by means of zinc dust. If this substance is moistened with 

 the base (in an atmosphere of nitrogen), a pretty violent reaction occurs five or ten 

 minutes later, and ammonia and zinc oxide are formed. 



5. The Chemical Action of a New Bacterium in Milk. 

 By Alexander Bernstein. 



Up to the present time the chemical action of bacteria on sugar has received 

 the largest share of attention, the alcoholic and acid fermentations offering them- 

 selves most readily for observation. 



In regard to the efl'ect of bacteria on casein, it has generally been considered as 

 sufficient to say that some bacteria seem to have a rennet-like action, whilst others 

 have a peptonising efl'ect. It was assumed that a certain class of bacteria have 

 the peculiarity of producing an enzj'me which curdles the milk under alkaline 

 reaction, and afterwards producing another enzyme which dissolves the curd 

 again. Such actions can be noticed if a milk is strongly heated and then left to 

 itself. 



The author succeeded in isolating a bacterium, which had such an unusual 

 effect en sterilised milk, that further studies appeared desirable. These investiga- 

 tions have been carried on by the author at the Hygienic Institute of Berlin. 



The special bacterium is a very short rod, .scarcely l/x* long and •5/i in diameter : 

 it shows rapid whirling motion, forms colourless liquid colonies on peptone- 

 gelatine, which is soon entirely liquefied ; on agar a white slimy growth ; on 

 potatoes a smooth brown skin. No spores could be observed. The microbe has 

 received the name Bacterium peptofaciens. 



A practical method of inoculating large quantities of milk with this bacterium 

 was next described, the object being to obtain a new product out of milk in which 

 all the casein is in a dissolved state, as it is well known that ordinary milk is not 

 easily digested by many grown-up persons on account of the undissolved state of 

 the casein. 



Milk which had been deprived of its cream by separators was used for this 

 purpose. After incubation during eight days at 20° C. the further action of the 

 bacterium wa.s prevented by heating the milk. This killed the bacteria and caused 

 coagulation of that part of the casein which had not been dissolved. A clear 

 filtrate was obtained : it had a yellow-reddish colour, an aromatic smell, and a taste 

 reminding one of almonds. 



The results of a detailed chemical analysis were given. It was shown that 

 more than one-half of the casein had been hydrated and formed into albumose and 

 peptone. The various reactions of the dissolved protein substances were stated. 



A small amount of lactic acid was formed, and a very slight amount of acetic 

 and butyric acids, these last two together coming only to 'Oo per cent. The bac- 

 terium does not produce any gaseous products, even after weeks of action. 

 Sulphuretted hydrogen, indol, and skatol were not formed. The sulphur of the 

 casein was still contained in the peptone. Ammonia was present in the form of 

 salts, the amount of ammonia being equal to '07 per cent. Of tyrosin only the 

 existence could be shown, the amount being too small to show crystals under the 

 microscope. 



Reference was made to similar products generated during the ripening of 

 cheese, which is entirely the action of microbes. 



' lAt=0001 mm. 



I 



