CONDENSED MILK. 285 



The specific gravity of preserved milk, containing cane-sugar, at 15 C., 

 varies between 1-2540 and 1-4038, being on an average 1-2820. Preserved 

 milk, without the addition of sugar, which is much used in the United 

 States of America, has not been prepared in Europe since 1880. The 

 chemical composition of American thickened milk, without the addition of 

 sugar, is as follows: 



Average. Limits of Variation. 



Water, 48-595 46-40 to 53-54 per cent. 



Fat, 15-668 13-12 19-80 



Nitrogenous matter, ... 17'806 13-61 26*50 



Milk-sugar, 15-403 12-50 17-75 



Mineral matter, ... 2*528 2*00,, 2-96 



100-000 



The specific gravity of American thickened milk is, on an average, at 

 15 C., 1'136. Attempts to condense skim-milk, mares' milk, and goats' 

 milk, have also been made. 



Shortly after the method introduced by Scherff for the steri- 

 lization of milk had become known, the idea was carried into effect 

 of rendering the condensed milk capable of being kept by sterilizing 

 it, and thus dispensing with the addition of sugar, which, by 

 imparting to it a very pronounced sweet taste, rendered it disagree- 

 able to many people. For this purpose experiments were carried 

 out during the years 1881 to 1883 in different parts of Germany 

 and Switzerland. Sterilized condensed milk was best obtained by 

 purifying the fresh milk by the application of centrifugal force, 

 and then boiling it in order to coagulate the albuminous part of 

 the nitrogenous matter. This was condensed in vacuum-pans to a 

 third or fourth of its original volume, and poured into metal 

 vessels of the same shape and size as are used in the factory at 

 Cham. The vessels, after being filled and soldered, are placed for 

 a short time at a temperature of about 120 C., the keeping quality 

 of the substance being tested by submitting it for a few weeks to 

 a temperature of from 30 to 40 C., and after the lapse of this 

 time seeing whether there have not been indications of fermen- 

 tation shown by distention at the bottom or at the top of the 

 vessels. If it be neglected to heat up the milk before it is con- 

 densed, the albumin is coagulated during sterilization, and renders 

 the contents of the can lumpy. 



