lo July, 1911-] The Bahcock Tester on the Farm. 



437 



compass ; place one point on the zero and see how far the other point 

 reaches. This will show how many spaces the fat tills, and the reading 

 gives the correct percentage of fat in the milk. 



Calculating the result. — The weight of the milk given by the cow, 

 nniltiplied by the test and divided by one hundred, gives the amount of 

 butter fat in pounds. To convert this approximately into commercial 

 butter, one-sixth is added to the fat result. 



Example.- — 35 lbs. of milk at 4.2 test = 35 x _)..> ^ ico = 1.47 lb. 

 butter fat + \ = 1.7 15 lbs. (practically if lbs.) commercial butter. 



Sulphuric acid. — The sulphuric acid should be a definite strength, i.e., 

 1.827 specific gravity. It is usually supplied by the agents at the correct 

 strength. Care must be taken in handling it as it is very corrosive. The 

 appearance of the fat, when the test is completed, will indicate if the acid 

 IS the correct strength or not. Instead of being a clear amber coloured 

 column it may have black or white specks mixed through it. Black specks 

 may be caused by the temperature of the milk or the 

 acid being too high when mixed, or too much acid being 

 used, or the acid being too strong. 



6 



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8. RE.\bi.\G .\IIi.K TE.ST. 9. RF-.^DING CRE.\M TE.ST 1 O. CRE.AM SAMl'LKR. 



It will he easy to discover in this way if the acid is too strong. If so, 

 use one or two c.c. less; if the fat comes out clearly, it will be correct. 

 On the other hand there may In- white specks of undissolved curd in the 

 fat column. This may be due to temperature of milk or acid btMng toe 

 low when mixed, too little acid being used, or not shaking sufficientlv to 

 dissolve all the casein when mixing ; this is particularly .so if too much 

 formalin has been used in the sample, or the acid is too weak. If not muci» 

 too weak, one or two c.c. more acid may bring the test out clearly, when tb'r 

 results should lie correct. If ihe stopper is left out of the bottle the acid 

 will ab.sorb moisture from the air and so become weaker. The acid should 

 be water white, but sometimes, through dust getting in or through othei 

 reasons, it turns d irk ; if vou get a clear reading nf the fat the acid will 

 be all right. Do not dilute by adding water. 



