6 ROYAL SOCIETY OF CANADA 



tube and condenser are used as in the preceding extraction. On freeing- 

 the tube from excess of alcohol, drying and weighing it, the amount of 

 substance extracted by alcohol is ascertained. These substances consist 

 of some of the products of the alteration of the casein, and seemingly 

 of those which give to the cheese its characteristic flavour. 



IV. Aqueous Extract. — This is obtained by taking the tube which 

 has been exhausted by alcohol, and treating it in exactly the same man- 

 ner with distilled water, or by allowing hot water to percolate through' 

 it. In this case a further quantity of soluble substance is removed,, 

 which is also derived from the alteration of the casein. Its amount i& 

 ascertained by weighing the dried tube and noting its loss in weight. 



V. Casein. — The residue of insoluble matter remaining in the fibre 

 after the removal of the water soluble constituents consists, without 

 doubt, mainly of casein which has escaped alteration. 



The following table T, contains a record of the results obtained in: 

 the above described series of determinations on samples of cheese pur- 

 chased in the Canadian market. It will be observed that these analyses 

 have been made in duplicate : — 



