THE INORGANIC CONSTITUENTS OF MILK 51 



Human Milk Camerer and Soldner 1 obtained the following 

 figures : 



Early milk . . .2-2 mgm. per litre 



Middle period . 2*0 



Late period . . . . ro 



Soxhlet obtained a number of samples at different periods of 

 lactation, and gives the following results : 



4th to 7th day (7 samples) . . . 1-2-2-2 mgm. 



together with 5 weeks (i sample) . average 17 mgm. 



Period unknown (2 samples) . 1-3-1 -6 



Later period (7th month) (i sample) . 1-5 



Although some samples in the early days have a lower iron 

 content than others, there seems to be a tendency for the content 

 to fall towards the end of lactation. 



Cows' Milk. Trunz found some tendency for the iron con- 

 tent to rise towards the end of lactation in one cow investigated, 

 but not in the other. The figures obtained varied greatly on 

 different days in the milk of the same cow. Thus in one cow the 

 content varied from 0-019 to 0-045 gramme per kilo, the greater 

 number of estimation being about 0-03 gramme per kilo. 



In the other cow the amount found varied from 0*009 to 0*023 

 gramme per kilo, the majority of the estimations being just below 

 0-02 gramme per kilo. 



Nottbohm and Dorr (1913) found a tendency for the iron 

 content to rise towards the end of lactation. There is considerable 

 variation in the amounts of iron given by different cows. The 

 occurrence of mastitis appears to lead to an increase in the iron 

 content and to simulate the condition of the end period of 

 lactation. 



The varying tendencies exhibited by human and cows' milk 

 in their iron content as regards the period of lactation has already 

 been shown to occur in the case of nitrogen and applies also to the 

 lime content. 



Langstein, and subsequently Edelstein and Csonka, state that 

 the iron content of milk increases on keeping, and they believe 

 that this is due to the passing into solution of small amounts of 

 iron from the cans. No experimental evidence has, however, been 

 brought forward to control this statement. 



Edelstein and Csonka used Lachs and Friedenthal's method 

 of estimation. They took milk from individual cows, milked 

 straight into the glass ; also mixed milk from the dairy at the 



1 Cp. also Camerer. 



E 2 



