CHAPTER II. 

 The Strength of Sulphuric Acid. 



14. Sulphuric acid should have a specific gravity 

 of 1.82—1.83 (Farrington and Well*) or not below 

 1.815 nor above 1.839. The strength of sulphuric 

 acid is shovs^n to some extent by the color of the 

 fat. When the temperature of both the milk and 

 the acid is 70° F., and the fat shows dark flakes or 

 is black, the sulphuric acid is too strong. When the 

 fat is very light colored the acid is too weak. When 

 it is found that the fat is blackened by too strong 

 acid, add less acid. If the fat is too light, add a 

 trifle more acid^ By experience the operator will 

 soon learn just how much acid to add in order to 

 get a clear, well defined reading. Very few carboys 

 of acid are exactly alike in strength ; ' therefore a 

 few tests made from any one carboy will indicate 

 the Strength of the acid and the amount necessary 

 caii easily be measured out for each milk' or cream 

 sample. 



15. Reflating the strength oi sulphuric acid. If 

 the acid is too strong it can be made of standard 

 strength by leaving the carboy open, as the acid 

 weakens by being exposed to the air. Since it takes 

 quite a time for the average creamery to use a whole 

 carboy of sulphuric acid it is not deemed advisable 

 to standardize the whole carboy at one time, but 

 rather standardize one gallon at a time. When a 

 carboy of sulphuric acid is all standardized there is 



* Farrington and MToll. Testing Millt and Its Products, 1904. 

 19 



