22 BULLETIN 524, U. S. DEPARTMENT OF AGEICULTURE. 



is ashed the added calcium salts will cause an increase in the alka- 

 linity of the ash, and especially in the percentage of calcium oxid in 

 the salt-free ash. It should be noted, however, that the alkalinity of 

 a butter made from limed cream, or even of one washed in lime water, 

 might be less than that of a natural butter with a high whey content, 

 but an increase in the percentage of calcium oxid in the salt-free ash 

 would at once reveal the use of lime at some stage. Perhaps by de- 

 termining the ratio of alkalinity to another constituent of the butter 

 ash, for example, phosphorus pentoxid, an independent method might 

 be developed for detecting neutralization. It might be necessary to 

 distinguish between a butter made from limed cream and a butter 

 given a " lime bath." If the alkalinity were below 20, the reaction 

 of a w^ater extract acid to litmus, and the percentage of calcium oxid 

 in the salt-free ash, corrected for calcium sulphate in the salt, well 

 above 25, the use of a limed cream would be indicated. If, on' the 

 other hand, a butter had an alkalinity of over 20, if the percentage of 

 calcium oxid in the salt-free ash was over 35, if its water extract was 

 alkaline to litmus, and if it gave a peculiar foam test and liberated 

 butyric acid on the addition of dilute sulphuric acid, it would be 

 strong evidence that lime had been added to the butter and not to 

 the cream. 



SUMMARY. 



The percentsfge of calcium oxid in the ash of milk, unneutralized 

 cream, and butter made from unneutralized cream varies within 

 fairly narrow limits, with a tentative maximum set at 25. 



When lime has been added to the cream in the process of manu- 

 facture this percentage is increased above 25, the increase varying 

 with the amount of lime added and the degree of washing. 



The ejffect of calcium impurities in the salt has been studied and a 

 method developed to correct for the chief impurity, calcium sulphate. 



It has been shown that the percentage of calcium oxid in the salt- 

 free ash of butter made from unneutralized cream will not exceed the 

 tentative maximum limit of 25, unless high percentages of salt with 

 much impurity are employed. 



Finally, attention has been called to a form of sophistication of 

 butter by chemical renovation. 



