CHAXCES OX KEEPING. 



355 



The change is not very rapid, and in the course of several 

 weeks the changes are often not very pronounced. 



Bell has recorded the following figures for the changes in the 

 insoluble fatty acids ; the butter in this case was kept for the 

 times indicated : — 



No. of weeks kept, . 

 Before keeping, per cent., 

 After 



12 7 7 6 8 6 



87-30 87-80 85-50 87-40 87-72 87-65 

 88-97 90-00 85-72 87-97 88-40 88-00 



Meth has made analyses showing the change in the insoluble 

 fatty acids produced when butter fat is kept. In each case about 

 a year had elapsed between the two analyses. 



Per lent. 

 Original insoluble fatty acids, . 87-43 

 Insoluble fatty acids, after kee[iing, 85-07 



The same observer has also examined old butter fat and old 

 butter (kept for about ten years) which had not been previously 

 analysed. 



The old butter fat was divided into two portions — one, com- 

 pletely bleached, contained 8.3 '52 per cent, of insoluble fatty 

 acids ; and the other, which still retained a trace of its natural 

 colour, yielded 83 '90 per cent. 



The results with the old Inittcr were as follows : — 



Lower portion, . . , 89-28 per cent, insoluble fatlv acids. 



„ washed, . 89-33 



Upper portion, . . . 90-94 „ „ „ 



Allen and Moor have examined two samples of butter which 

 had been kept for five and a half years. The following table 

 gives tlirir results : — 



TABLE LXXXIII. 



' This figure was determined I)y the author on a duplicate sample. 



