8o DAIRY ANALYSIS 



milk-blended butter ; in the latter the " curd " will be 

 in the proportion of i part for each 10 parts of water, 

 in the former much less, 



A washed butter may be distinguished from an un- 

 washed one by containing less than i part of curd to 

 10 parts of water, usually only about 0.5 part ; un- 

 washed butter contains about i part ; a larger percen- 

 tage of curd indicates that the butter was churned from 

 very sour cream, and will not keep well, or that it has been 

 adulterated with casein. A higher percentage of casein 

 than 0.5 indicates the presence of added casein ; this 

 form of adulteration is not uncommon. Cane sugar 

 or honey is occasionally added ; the test given on 

 p. 54 applied to the aqueous portion obtained on 

 melting out will detect this. The percentage of salt 

 should not exceed 3 in a mild salt butter, but may go 

 up to 5 per cent, or more in other samples. Irish 

 pickled butters are high in water and in salt. 



The Preservatives Committee of the Local Govern- 

 ment Board recommended that no preservative except 

 boric acid be allowed in butter, and that only to 

 the extent of 0.5 per cent. ; this has not yet been 

 legalised. 



The detection of margarine is more difficult ; the 

 Butter Regulations Committee of the Board of Agricul- 

 ture has recommended a limit for the Reichert-Wollny 

 figure of 24c.c., but their recommendation has not yet 

 been adopted. 



This figure, as well as 89 as a superior limit for 

 insoluble fatty acids, 5 per cent, as the minimum for 

 soluble fatty acids, 22.0 per cent, for the potash re- 

 quired for saponification, 0.910 for the density, 42 per 

 cent, for the iodine absorption, and 48 as a maximum 

 Zeiss butyro-refractometer figure, may be taken as 

 indicating the border-line of genuine butters. Certain 

 butters, however, especially those prepared from the 

 milk of cows exposed to cold climates and near the 

 end of lactation, yield figures beyond these limits. The 

 appearance on melting, and under polarised light, may 



