THE SOXHLET BOTTLE. 205 



whole day is boiled at once, portions of this being taken from time 

 to time as required. Through ignorance on the part of the mother, 

 or by the carelessness of the nurse, it often happens that this food 

 is supplied to the infant in a partially decomposed condition. A 

 particular fault, frequently committed, is that the bottle, which 

 has been lying for two or three hours in the warm nursery, is 

 refilled from the vessel containing the bulk, without the residual 

 milk from the preceding meal having been removed. That such 

 carelessness (frequent though as constantly denied) must conduce to 

 digestive disorders requires no further demonstration, the high rate 

 of infant mortality from intestinal catarrh being sufficient evidence. 

 For this reason it has been attempted to render milk stable 

 by boiling it in small bottles, holding just sufficient for a meal, 

 and closing the same with a stopper (impervious to bacteria), which 

 is removed only just before use. This is the fundamental idea of 

 the so-called Soxhlet method of sterilising milk, in which several 

 bottles are inserted in a movable frame and immersed in a tin pan 

 containing water, which is thereupon kept on the boil for forty 

 minutes. SOXHLET (I.) employs latterly, as automatic stopper, an 

 indiarubber disc resting on the ground mouth of the bottle, and 

 prevented, by means of a loose-fitting tube, from becoming displaced 

 laterally. The gases and steam given off from the milk in boiling 

 escape into the air by forcing up the disc, and when the operation 

 is finished and the apparatus is removed from the fire, this clack- 

 valve is kept tight by the pressure of the outside air, the partial 

 vacuum within the bottles being generally equivalent to 100 m.m. 

 of mercury. This stopper not only prevents access of air, but also 

 debars dealers or purchasers from opening the bottle with fraudu- 

 lent intent, since it cannot be closed again. This ensures the 

 purchasing public receiving the milk in the same unadulterated 

 condition in which it left the dairy. Similar to Soxhlet's method 

 are those of Egli and Escherich, a short description of which (as 

 also of those of Soltmann, Bertling, Gerber, and Stadtler) will be 

 found in a comparative treatise by EMMA STRUB (I.). 



125. Germ-Content of Milk Treated by the Soxhlet 



Method. 



The foregoing method would meet all requirements were the 

 destruction of the pathogenic and the lactic acid bacteria alone in 

 question. However, as has previously been mentioned, milk also 

 contains very hardy bacterial spores, able to withstand such a 

 course of boiling as that specified. The number of such spores 

 varies, and is greater in proportion as the degree of uncleanliness 

 in the attendance on the cows and in the operation of milking 

 increases. These milk bacteria (which resist the ordinary means 

 of sterilisation) were investigated with regard to their properties 

 and action by C. FLUGQE (II.). A few of them are very widely 



