10' JuLT, 1918.] The Bdhcoch Tester on the Farm. 



405 



Sulphuric acid. — The sulplmric acid should be of a definite strength. 

 i.e., 1.827 specific gravity, and it is usually supplied by the agents at this 

 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 of the correct strength. 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 by the use of too much acid, or an acid of too 

 high a strength. 



It will be 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, the 

 result will be correct. On the other hand there may be white specks 

 of undissolved curd in the fat column. This may be due to temperature 



5.— Milk Test Bottle. 



6. — Cream Test Bottle. 



7.— Skim Milk Bottle. 



of the milk or the acid being too low when mixed, too little acid being 

 used, or to the sample not having been shaken sufficiently at time of 

 mixing to dissolve all the casein. The specks will be parti- 

 cularly noticeable- if too much formalin has been used in the 

 sample, or if the acid is too weak. If not much too weak, 

 one or two c.c. more acid may bring the test out clearly, when 

 the results should be correct. If the stopper is left out of the bottle 

 the acid will absorb moisture from the air and so become weaker. The 

 acid should be water white, but sometimes, through dust getting in or 

 through other reasons, it turns dark; if a clear reading of the fat is 

 obtained, it is evident that the acid is of the right strength. Do not 

 dilute by adding water. Very serious accidents have frequently occurred 

 by this being done. 



Specimen forms for keeping a record of both individual cows and 

 that of the whole herd are shown on jjages 408-9. 



