lULINO'IiS STATE DAIRYMEN'S ASSOCIATION. 155 



become cooled, the other has been warmed, and the third 

 stood at the room temperature of 70 degrees Fahrenheit for 

 twenty minutes; add acid to the milk in each test bottle and 

 proceed with the test as usual. 



Second — Measure some of the same milk into three test 

 bottles — D, E and F. Into the milk in test bottle D pour 

 the usual amount of weak acid; then add the same amount 

 of strong acid (normal strength) to bottle E, and use still 

 stronger acid in test bottle F, and complete these tests in the 

 usual way. 



These six tests are made of one sample of milk so that 

 the original fat of this milk is doubtless of one and the same 

 color in each of the six test bottles at the beginning of the 

 experiment, but after the tests have been completed, as de- 

 scribed, the operator will notice that the fat in the necks of 

 test bottles A (cold milk) and D (weak acid) is much lighter 

 colored than that in C (warm milk) and F (strong acid), and 

 that the color of the fat in B (normal temperature) and E 

 (normal acid) is somewhere between that of the others. 



A similar chemical action can be observed when acid 

 drops on a piece of pine wood. The color changes from light 

 to dark yellow and finally is blackened or charred. Strong 

 acid blackens wood almost immediately, but sufficiently weak 

 acid only sightly color the wood so that in this way the color 

 of the wood can be changed by the strength of the acid. 



Sulphuric acid decomposes the vegetable or organic sub- 

 stances, more or less according to the intensity of its action. 

 This action is accelerated by heat and the strength of the 

 acid. The acid may be so strong and the heat so great that 

 the vegetable substance is entirely dissolved and again it 

 may be only partially decomposed by weak or cold acid. Sul- 

 phuric acid dissolves some vegetables or organic substances 

 more easily than others, as is shown by its action on the 

 milk solids when it is used in the Babcock test. The casein 

 suspended in the milk is easily dissolved, while the fat is 

 not, but both the casein and fat as well as the pine wood 

 are organic substances, and may be, with sufficient heat and 

 strength of acid, entirely dissolved or oxidized. 



This discussion of some of the properties of sulphuric 

 acid and the influence it may have on the color of the fat 



