THE MICROSCOPE IN PHYSIOLOGY. 103 



milk is that with water. Now, some few persons who 

 have not reflected closely upon the matter, may be 

 disposed to make light of the adulteration of milk with 

 water, and to speak in rather facetious terms of the 

 cow with the iron tail ; but it is surely no light matter 

 to rob an important article of daily consumption, like 

 milk, of a large portion of its nutritious constituents. 

 But the adulteration with water is not the only adul- 

 teration to which milk is liable ; the large addition of 

 water frequently made to it so alters its appearance as 

 to cause it to assume the sky-blue colour so familiar to 

 us in our school-boy days, and so reduces its flavour 

 that it becomes necessary to have recourse to other 

 adulterating ingredients namely, treacle, to sweeten it, 

 salt, to bring out the flavour, and annatto, to colour it. 

 Further, there is no question but that chalk, cerebral 

 matter , and starch have been, and are occasionally, 

 though rarely, employed in the adulteration of milk. 

 With regard to the use of chalk, a manufacturer of pre- 

 served milk recently informed us that it sometimes 

 happened to him to find carbonate of lime or chalk at 

 the bottom of the evaporating dishes or pans on the 

 evaporation of large quantities ot London milk." 



These remarks will be sufficient to show you the 

 use of the microscope in the detection of adulteration 

 in food. Dr. Hassall's book will supply you with 

 abundance of information on the subject, should your 

 microscopic predilections point that way. 



It is very curious to see the formation of crystals 

 taking place under the microscope. If you evaporate 

 a solution ot common salt on a glass slide, and allow 

 it to cool, and then cover it with a bit of thin glass, 

 you will see some beautitul cubes of chloride of sodium. 

 In the same simple way you may obtain crystals of 

 several salts for examination. On the other side are 

 represented forms of the crystals of ammonio-phosphate 



