MILK. 153 



dissolves the envelope. On now treating with ether 

 the globules will be dissolved. 



7. The colostrum (milk secreted during the first two 

 or three days after parturition) is characterised by the 

 presence of granular bodies. Examine under the 

 microscope : the granular bodies will be seen to be 

 composed of irregular aggregations of small fat glo- 

 bules, and united by an albuminous amorphous granu- 

 lar substance. Treat with iodine water ; the albumen 

 will be dyed yellow.' Potash and acetic acid break up 

 these granular bodies. 



8. Evaporate 20 cc. of milk to dryness in a small 

 weighed porcelain or platinum crucible on the water- 

 bath. Dry in an air-bath for several hours at 110 C. 

 and weigh ; the increase in the weight of the crucible 

 gives the solid residue in the milk. 



9. Ignite the dried residue over a Bunsen or Argand 

 burner; allow to cool and weigh. The difference 

 between this weight and the original weight of the 

 crucible gives the ash of the milk. 



Milk contains about 10% solid residue, and 0*1 to 

 0-5% of ash. 



10. Evaporate 50 cc. of milk on a water-bath almost 

 to dryness in a weighed porcelain dish; add acetic 

 acid. Exhaust the residue successively with ether, 

 alcohol, and water. Dry the exhausted residue and 

 weigh ; the increase in the weight of the dish gives the 

 caseine in the milk. 



11. Evaporate the ethereal extract to dryness in a 

 weighed crucible and weigh ; the increase of weight 

 will give the quantity of fat. 



