KOUMISS. 297 



micro-organisms will grow through the filter, but it appears to 

 be firmly established that pathogenic germs are not among 

 these. To secure ef&cient working, these filters should be fre- 

 quently cleaned, and it is advisable to sterilise them by steaming 

 from time to time. They have the advantage of being easily 

 tested, as when efficient they will not, when wet, allow air under 

 a pressure of 10 lbs. per square inch to pass ; whUe, if defective, 

 a passage is afforded at any place which will allow micro-organisms 

 to traverse the filter. 



Products formed from Milk by the Action of Micro-Organisms. 

 — Besides butter and cheese, in the manufacture of which micro- 

 organisms play an important part, several preparations are made 

 from milk ; among these may be mentioned koumiss, kephir, and 

 mazoum. 



Koumiss. — This preparation was originally made from mare's 

 milk by the Tartars. It is a product of combined alcoholic, 

 lactic, and protein-hydrolytic fermentations on milk. Its pro- 

 duction first from mare's milk is probably due to the fact that 

 the sugar of this milk very easily undergoes alcoholic fermentation. 



The following analyses of mare's milk koumiss are by Vieth ; — 



TABLE LXVIII. 



Water, 



Alcohol, . 



Lactic acid, 



Sugar, 



Casein, 



Albumin, 



Proteoses, 



Fat, 



Ash, 



Koumiss is now very largely made from cow's milk by the 

 silcction of special organisms. 



The following analyses of various kinds of koumiss have been 

 made by Vieth on the preparations of the Aylesbury Dairy 

 Company. The carbonic acid present has not been taken into 

 account ; it is, however, always present (except in the earlier 

 stages) in sufficient amount to render the koumiss highly effer- 

 vescent ; hence, the preparation has been termed " milk cham- 

 pagne " on this account. 



Tho term " casein " includes meta-caseins. 



