49 



against the light while it is allowed to run in a broad sheet back 

 into the box. 



Any imperfections, as the existence of more or less granules, of 

 which good milk should contain but few, can thus be observed. 



A good normal condensed milk should be of the consistency of 

 honey ; it should possess an agreeable flavor, and must be easily dis- 

 integrated, without the separation of a flocculent residue, by mixing 

 it with from four to five parts of water. Only products prepared 

 by deficient processes show abnormalities. 



The microscope reveals the presence of butter globules, crystals 

 of sugar, and groups of normal milk salt crystals. 



Crystals of a moss-like structure are found in milk only when 

 the process of condensation has been carelessly performed. 



The microscopical observation is greatly facilitated if the con- 

 densed milk is brought upon the slide with a drop of oil, which 

 will not aiiect the sugar crystals and salts. Oane sugar appears in 

 large monoclinic prisms ; milk sugar in four-sided tri-metric prisms ; 

 calcium lactate forms tufts of fine needles. 



The specific gravity is determined in a flask of known weight 

 and contents, in the manner described above. 



Chemical Examination. 



For the determination of the solids and ash, two to three 

 grms. of condensed milk are accurately weighed in a covered 

 platinum crucible, coagulated by means of absolute alcohol, and 

 treated as described on page 23. 



Care must be taken that the sample is perfectly free from solder. 

 Its presence would not only produce inaccurate results, but would 

 destroy the platinum crucible when the solids are incinerated. 



The albuminates and the fat are determined in two to three 

 grms. accurately weighed in a covered beaker ; 100 to 150 grms. 

 of water are then added, the whole mixed thoroughly and precipi- 

 tated with copper solution, as usual. From 1.5 to 2 c.c. of copper 

 solution, and 0.Y5 to 1 c.c. alkali solution are required. The 

 remaining part of the process of manipulation is the same as 

 previously described (see page 24). 



The determination of the cane sugar and milk sugar is made in 

 such a manner that the latter is directly determined by means of 



