65 



microscope as strongly refractive fat globules of varying size, 

 which, on account of the protection afforded by the flour, do not 

 easily unite, even after dilution with water. 



To better distinguish them, a small quantity of the flour is 

 brought on the slide, and then a solution of iodine in water (1 : 50) 

 is added. Starch and dextrine are both distinctly colored, while 

 the fat globules assume but a very slight yellowish tint on their 

 extreme edge, and are easily recognized by their strong refractive 

 powers. It occasionally happens that even starch granules ai'e not 

 colored by iodine, and may then be taken for fat globules. Addi- 

 tion of potash will swell these and dissolve them gradually, while 

 the fat globules remain unaltered behind. 



Eliza McDonogh, in her dissertation' on milk-food, considered 

 herself justified to conclude from the absence of sugar crystals in 

 these foods, that no condensed milk had been used in their prepar- 

 ation, since this always shows sugar crystals. Miss McDonogh and 

 Prof. Wyss would not have come to this conclusion if they had 

 considered the method of manufacturing these foods, which totally 

 differs from that of condensed milk. They even neglected to test 

 these foods qualitatively for fat, and failed, on their microscopical 

 examination, to recognize the butter globules. Their views are, 

 therefore, without value. Owing to the process of manufacture, 

 the butter globules are very finely divided and may, therefore, be 

 easily taken for starch. 



Beside the amylum and fat globules, the microscope Avill also re- 

 veal other normal constituents, the vegetable albumen and cellulose 

 fragments. 



Abnormal Constituents. 



As abnormal constituents, fungi and the meal-mite may be 

 found, which have their origin in the use of inferior flour. 



Chemical Analysis. 



The reaction of milk-food, after boiling with water, is acid. 

 This is caused by the presence of large quantities of phosphates, 

 and also by the presence of acids of the fatty series. 



Determination of Water. 



3 to 4 grms. of milk-food are taken from the center of a box 



