4S0 



Examination of flour ^ mcal^ etc. — For tests of tliosc mntoiials a tube 

 of a1)oiit 15 c. ('. capacity is used, similar in sliajx' to those used for test- 

 inj"- uiilk, but reversed, tlie ueck beiu<>' closed at the outer end and 

 paduated to tiftietlis of a cubic centimeter. Wlien 1 <iram eacli of dif- 

 ferent kiuds of meal was placed in the tubes nearly filled with water, 

 shaken until tlu' luin]is were all broken, and then whirled in the centri- 

 fu<it' at the rate of L',0()0 to 2,."»00 revolutions per minute for exactly o 

 minutes, the space occupied by the meal in the neck (bottom) of the tube 

 was found to dei)end upon the fineness and specific }>Tavity of the par- 

 ticles, being- larger the lighter and larger the particles of meal. Thus 

 in a test of a number of different kinds of meal and starch the space 

 occupied by 1 gram of material after whirling 5 minutes ranged from 

 ]li.() (rice starch) to oO tenths of a cubic centimeter. Alcohol and ether 

 Avere tried in place of water, but the latter was found more satisfactory. 

 It is claimed that adulterations of bran, flour, and the like may be 

 detected by this means and quantitatively' estimated, at least ap])roxi- 

 mately, and the results of numerous tests in this directicm are reported. 

 The microscope is recommended as a A'^aluable supplement in recogni- 

 zing the character of the adulterants. 



Butter anaJiiais. — The tul)e described above is also used for testing 

 butter. To save time the sample of butter is measured instead of 

 weighed. For this i)urpose a thin piece of glass tubing, fitting into the 

 opening of the test tube and of such length as to contain 10 c. c, is used. 

 Tills measuring cylinder is ti^lled by pressing it into the butter, and the 

 butter is removed from the ends by passing a glass plate over them. 

 The cylinder is then wiped and placed in the wide iiart of the test tube 

 which has been heating in the water bath. The butter is quickly melted 

 and runs down into the tube. The measuring cylinder is then removed 

 and the tube is whirled in the centrifuge running at about 2,()()0 revolu- 

 tions per minute for 2 to 3 minutes. At the end of this operation two 

 layers are usually i^lainly perceptible in the aqueous portion, which is 

 shariily divided from the layer of liquid fat above it. The lower aqueous 

 layer is nearly clear and contains crystals of salt, mineral .substances, 

 etc.; the upper layer consists priiici])ally of casein suspended in water. 

 The relation of these two aqueous layers to each other is said to be very 

 Aariable. Their sum represents the buttermilk content of the samijle. 

 Ten minutes is said to be sufficient for the test. 



As the butter fat so separated is in a nearly pure condition, it maybe 

 saponified to get the fatty acids and the index of refraction taken. For 

 the saponification a tube is used, which is similar to the one used in most 

 of the rapid milk tests, except that the neck widens above the graduated 

 part into a bulb of about a third the capacity of that below. The nar- 

 row pai't between the two bulbs of 1.1 to 1.5 c. c. capacity is graduated 

 to fiftieths of a cubic centimeter. One c. c. of the butter Jiit is measured 

 out into the tube by means of a pipette at a temperature of 100° C, 

 butter fat, pipette, and tube being previously heated together in a 



