DETERMINING GREASE AND DIRT IX WOOL. 
after washing with gasoline and the weight of the same conditioned 
wool after washing with soap and water. 
BASIS OF THE INDEX FIGURES. 
A difference in dirt content of raw wool would cause a difference 
in the percentage weight of grease and clean wool in samples that 
FlG 4_De-rea^ed wool airing after three treatments of gasoline. The two large cans in the mr.L-round 
are shown°collecting the gasoline returned from the gasoline still In the rear. Air pipe, A. connects lowei 
and upper parts of blower dryer used for drying wool after washing. 
are similar except that one is of lower dirt content than the other. 
Likewise, a difference in grease content would cause a realignment 
of percentage figures. In order, therefore, to obtain a fair and 
constant basis for indices of grease and dirt, the actual weighl oi 
each of these materials removed is considered in its relation to the 
