No. 4. 



Frye's Lactometer. 



121 



of his dairy, and to select such breeds of 

 cows, and ^ive them such food as will yield 

 a rich supply of milk. To heads of families 

 and venders of milk in cities, it will prove 

 equally advantag-eous in detecting frauds 

 practised by milk-men, in feeding their cows 

 on dops, and in adulterating- their milk with 

 water or otherwise. And above all, to mo- 

 thers and nurses it will be invaluable in af- 

 fording them the means of testing the purity 

 of the milk on which they feed their chil- 

 dren. Medical writers afford innumerable 

 proofs of ill health, disease, and even death 

 itself in children and adults, where impure 

 milk has been taken as food. 



According to Berzelius the obvious com- 

 ponents of milk are cream, curd, and whey. 

 One thousand parts of cream of cow's milk, 

 of a specific gravity of 1.024, contains of 



Butter, 45 



Curd, 35 



Whey, 920 



1,000 



The remaining skimmed milk has a spe- 

 cific gravity of about 1.033, and consists of 



Water, 929 



Curd with a trace of butter, 28 



Sugar of milk, 35 



Lactic acid, lactate of potash, and 



a trace of lactate of iron, 6 

 Muriate and phosphate of potash, 



and earthy phosphates, 2 



1,000 



If we e.xtract the curd, the remaining 

 substances constitute whey. The curd of 

 milk, or caseous matter, partakes in many 

 of its chemical properties, of the nature of 

 albumen ; in other respects it resembles ve- 

 getable gluten, more especially in the fer- 

 mentation which it undergoes when kept in 

 a moist state. Hence it may be considered 

 as partaking of the nature both of vegetable 

 and animal food. 



The quality of milk, and, consequently, 

 the proportions of the several constituents 

 above mentioned, vary with the breed of the 

 cow, with the food on which she is sustained, 

 with the time that has elap-ed since she 

 gave birth to her young, with her age, state 

 of health, and with the season of the year; 

 but in most cases this fluid contains the 

 same substances, though in different quanti- 

 ties. In warm weather milk contains more 

 butter; in cold, more cheese and sugar. 



The instrument in question is constructed 

 and for sale at ^\ each, including a tin case, 

 by Messrs. Frye & Shaw, 222 Water street, 



New York, and may be described and used 

 as follows : 



Lactometer. 



n 



w 



Croton water 



I milk and | water 



^ milk and | water 



% milk and \ water 



Pure Orange Co. milk 



20 



40 



60 



80 



100 



It will be understood by the annexed cut, 

 that the two extremes of the scale of the 

 instrument are based upon Croton water at 



