396 



THE MILK OF MAMMALS OTHER THAN THE COW. 



green iu colour, the fat should be extracted with dilute hydro- 

 chloric acid, and the amount of copper estimated and subtracted 

 from the weight. The refractive index of the fat may be deter- 

 mined. The Gooch crucible is dried to constant weight, and 

 ignited ; the difierence between the two weights gives the pro- 

 teins. The milk-sugar may be estimated in the filtrate by 

 Fehling's method. 



The author has found that the aldehyde fig-ure multiplied by 

 0134 gives a close approximation to the proteins. 



Comparison with Cow's Milk, — The following differences 

 in composition of the various constituents from that of the cow 

 have been noticed ; — 



Fat. — This is very low in volatile acids (see p. 391). It 

 appears to contain free fatty acids ; Leeds noted that many of 

 the fats extracted from the copper-protein precipitate obtained 

 by Eitthausen's process were tinted green ; Carter and the 

 author confirrned this, and found the following percentages of 

 copper oxide (CuO) in the fats thus extracted : — 



2-80 



1-27 



0-87 



,0'62 



30 



The copper could be easily removed by shaking with dilute 

 hydrochloric acid, and the fat behaved to copper salts in every 

 \vay as if it contained free fatty acids. 



Carter and the author found the refractive index at 35° C. to 

 vary from 58 '4° (in a milk which upset the child, which finally 

 died in convulsions) to 48 ■"2° (in a milk on which the child throve 

 remarkably well). The analyses of these two samples were : — 



Sugar. — Carter and the author found that the sugar crystal- 

 lised in rhomboid plates (not the wedge-shaped crystals of milk- 

 sugar), and had a specific rotatory power of [a]u = 487°. 



The sugar was estimated by difference iu the milk, as it was 

 found that polarisation and estimation by Fehling's solution 

 did not give satisfactory results. It was found that the gravi- 

 metric results were from 0'56 to 0"98 per cent, below the difierence, 

 and averaged 0'71 per cent, below, while the polarimetric results 



