374 MILK AND THE PUBLIC HEALTH CHAP. 



The writer 1 in 1902 examined 33 samples of "sterilised 

 milk " bought in Cardiff dairies and found only 17 (or 51 per 

 cent) sterile. 



Eobertson and Mair 2 examined milk sterilised in bottles 

 and supplied to infants by the Leith Corporation from the 

 Infant Milk Depot. They examined 90 samples, finding 

 only 14 (or 15 per cent) sterile. They concluded that the 

 reliability and safety of the milk depended largely upon the 

 temperature at which it was kept afterwards. 



Lubenau 3 concluded that the Bacillus peptonificans was the 

 cause of an epidemic of gastro-enteritis, but the evidence he 

 adduces is most inconclusive. In ordinary milk this group of 

 bacilli are present, but are overgrown by the ordinary lactic 

 acid bacilli. 



The bacteria left in boiled milk are of two classes 

 anaerobic and aerobic spore-bearing bacilli. From the evidence 

 it would appear that no very harmful effects are to be antici- 

 pated from these groups of bacilli, if boiled, or commercially 

 sterilised, milk is consumed within a reasonable period of pre- 

 paration, or if kept cooled meanwhile. Certainly all sterilised 

 milk should have the date on which it is prepared stamped 

 upon it. It must also be put up in bottles with proper 

 stoppers. For practical purposes it is necessary for the 

 stopper to be attached to the bottle, otherwise it is certain 

 to be lost, while a fresh rubber ring should be used each time. 

 Fig. 33, p. 296, illustrates the ordinary type of bottle or stopper 

 used. 



Ordinary domestic boiling of milk is allied to commercial 

 sterilisation, and may conveniently be studied here. Here the 

 temperature does not reach 100 C., indeed it rarely exceeds 

 97 C. owing to the milk "boiling" and frothing over when 

 that temperature is reached. 



As regards the efficiency of domestic boiling of milk to 

 kill pathogenic bacteria, it would appear, from a consideration 

 of the thermal death-points in Chapter IV., that it may be 

 relied upon to kill pathogenic bacteria, including B. tuberculosis, 

 particularly if the heating up be done slowly. It is a pro- 



1 Annual Report 1902, Cardiff and County Public Health Laboratory. 

 2 British Medical Journal, 1904, vol. i. p. 1122. 

 8 Centralbl.f. Bdkt. t Abt. Orig. I. xl. p. 433. 



