THE SOLUTIOX OF ANALYTICAL PROBLEMS. 249 



This milk was unusually ricli ; it is probable that it contained 

 an excess of cream. It was tte other portion of the milk (which 

 naturally was deficient in cream) that was poor. 



Pkoblem V. — To determine reason of unusual taste and 

 smell. 



Example a. — The smell was faint and like stale fish, and the 

 taste soapy and unpleasant. 



The following were the analytical figures : — 



Specific gravity. 

 Total solids. 

 Fat, . 

 Ash, . 

 Solids not fat, 



1-0364 

 11-56 per cent. 

 2-39 „ 

 105 

 9-17 



The milk was alkaline and the ash titrated with phenol- 

 phthalein ; had an alkalinity equal to 0-33 per cent, of NaoCO,. 



It was concluded that an addition of 0*3 per cent, of sodium 

 carbonate had been added. 



Example h. — The milk smelt of vinegar and curdled on 

 warming. 



The analytical figures were : — 



Specific gravity, . . 1-0329 



Total solids, . . 12-45 per cent. 



Fat, . . ... 3-50 



Ash, 0-74 



Solids not fat, ...... S-9o ,, 



Acidity, .50° 



The milk was curdled by phosphoric acid ; 60 c.c. of the whey 

 were distilled : — 



X 



The first 10 c.c. took . 1-3 c.c. alkali. 



,, second ,, . . 1-S „ ,, 



„ third „ . . 1-9 „ 



It was evident that the milk contained an acid somewhat less 

 volatile than water ; this corresponds with acetic acid, and the 

 whey distilled as a solution containing O'll per cent, of acetic 

 acid, which is equivalent to 2 per cent, of vinegar. 



Example c. — The milk had a faint burnt taste. 



It contained 0"42 per cent, soluble albumin. 



On centrifuging, a deposit was obtained which appeared to 

 consist of proteid matter ; it was much browned. It was there- 

 fore concluded that the milk had been placed in a vessel, in 

 which burnt milk had previously been kept. 



