TESTING MILK AND CREAM. 171 



accurately. For this purpose the Station is having a special 

 weighing scale made with which one can weigh nearly as rapidly 

 as he can measure with a pipette. When completed it will be on 

 sale by dealers in testing apparatus. 



PRECAUTIONS. 



That good results and clear separations can be obtained by 

 the previously described modifications the writer and others 

 connected with the College have fully demonstrated. It is 

 necessary, however, that certain details be strictly observed to 

 attain success and to make those points more prominent they 

 are repeated as precautions. 



1st. The acid must be of the proper strength; — 1.82 specific 

 gravity at 60 degrees Fahrenheit is more universally successful 

 than a stronger acid, though 1.825 may be used in some cases. 

 With very rich milk 20 to 21 c. c. of acid of 1.82 specific gravity 

 works much better than a smaller quantity of strong acid, prob- 

 ably because there is less water in rich milk to properly dilute 

 the acid than in poor milk. Rather thin milk will give good results 

 with acid of quite varying strength. If the acid is too strong 

 the fat will be blackened or black particles will appear in the 

 lower part of the fat column. If the acid is not strong enough 

 the fat will appear cloudy and white particles of curd will collect 

 at the lower part of the column so that an accurate reading can- 

 not be made. 



2nd. The milk or cream should not be colder than 70° Fahrenheit 

 or warmer than 80° Fahrenheit when the acid is added. If the 

 milk or cream is too cold the curd will not all be dissolved in the 

 time allowed, and the fat will appear cloudy with white particles 

 in the lower part of the column which will interfere with the 

 reading. If the milk or cream is too warm the action of the 

 acid will be too violent, the fat will be burned and the whole 

 column appear blackened or if only slightly burned black par- 

 ticles wall appear in the lower part of the column. 



3rd. The acid and milk or cream must be thoroughly mixed 

 together and the mixture stand not less than five minutes before hot 

 zvater is added; othenuise a clear separation will not be obtained. 

 It is also best to shake the bottle again slightly, just before 



