DETECTION OF LIME USED IN DAIRY PRODUCTS. 19 
because of an increase in the salt- free asli without a corresponding 
increase in the calcium oxid in the butter. In the ashing process the 
magnesium chlorid is decomposed with loss of chlorin and the salt- 
free ash is increased by the equivalent magnesium oxid. This point 
is well illustrated in Table 14. But it would be only in the case of 
a butter salted with large quantities of salt of exceptionally high 
magnesium chlorid content that a serious lowering of the calcium 
oxid determination would result in a butter made from neutralized 
cream being classed as made from unneutralized cream. 
SODIUM SULPHATE. 
The use of salt contaminated with compounds other than calcium 
chlorid or calcium sulphate causes a lowering of the percentage of 
calcium oxid in the salt-free ash. Sodium sulphate, for example, in- 
creases the salt- free ash without increasing the calcium oxid. If it 
were known that the salt used contained sodium sulphate its effect 
could be calculated as easily as that of calcium sulphate. Fortu- 
nately, the amount of impurities other than calcium salts in American 
dairy salt is small and their effect is almost negligible. 
INTERPRETATION OF RESULTS. 
The figure 25 as the maximum percentage of calcium oxid in the 
salt-free ash of unneutralized butter is considered a good working 
standard. It allows considerable latitude for the effect of calcium 
impurities in the salt. If the CaO figure of any particular butter is 
below 25, the butter may immediately be classed as made from un- 
limed cream. 
If the brand of salt used in the manufacture of any given sample 
of butter could be ascertained the interpretation of results of analy- 
sis would be greatly simplified. Analyses of the most widely used 
brands of American dairy salt would be useful in connection with 
this work. 
Butters with a percentage of calcium oxid in the salt-free ash of 
between 25 and 28 should be classed as suspicious. After correction 
has been made for calcium sulphate, determined from the sulphate 
present, if the percentage of calcium oxid in the salt-free ash is 
still above 25, the butter was made from a limed cream. If the CaO 
figure drops from above 25 to below 25, the apparently high percent- 
age was caused by the calcium sulphate in the salt used, and the butter 
must be considered as made from unlimed cream. A butter which 
contains more than 28 per cent of calcium oxid in the salt-free ash, 
especially when the percentage of salt or sulphate is low, can be 
identified as made from a neutralized cream. A sulphate determina- 
tion should be made on all butters which show a CaO figure above 
