

APPLICATION OF ANALYSIS 55 



should be applied, and the soluble albumin estimated 

 (P- 35) ; a deficiency of albumin below 0.35 per cent.; 

 or the non-production of colour with para-phenylene- 

 diamine or ortol will show that the milk has been 

 heated, and as the cream rises very slowly on heated 

 milk, the milk has been called poor because cream is 

 not apparent in a short time. Occasionally a sample 

 called poor turns out to contain a high percentage of 

 fat ; this would show that the milk has been standing 

 long enough for the cream to separate and it is then 

 divided into a rich and a poor portion. 



A not unusual practice is for the servants in a house- 

 hold to pour off a portion of milk from a can which has 

 stood some time for their own consumption, and remove 

 the cream, and to send the rest of the milk, thus 

 impoverished, for the consumption of the other members 

 of the household. (P* 



The Cause of Sweet Milk. Milk is sometimes 

 alleged to be sweet. Cane sugar may be detected by 

 adding to 10 c.c. of milk o.i gramme of resorcinol and 

 i c.c. of strong hydrochloric acid ; on standing in 

 boiling water for five minutes a red colour is produced 

 if cane sugar be present; it may be estimated! by 

 Harrison's method (p. 47). If all the figures for solids 

 not fat, ash, sugar, and proteins are equally high, the 

 milk has simply been concentrated, usually by boiling ; 

 the solids not fat have been found as high as 17.5 per 

 cent, in a case of this kind. 



The Cause of High Colour. If the colour is yellow 

 and the fat separated by the Gerber process is very 

 much darker than usual, and the cream separating is 

 much yellower than the skim-milk, the high colour is 

 natural. 



If this is not the case artificial colours should be 

 tested for ; annatto is detected by making the milk 

 alkaline with sodium bicarbonate, immersing a strip 

 of filter-paper in it, and allowing to stand till next day ; 

 in the presence of annatto the strip is stained brownish. 

 Coal-tar dyes of the azo group give a pink colour when 



