12 



LEATHER INVESTIGATIONS: SOLE LEATHERS. 



coarse powder in any convenient way. The leather may be rasped, 

 cut with a chisel or shears, ground in a mill, or sawed. Weigh 100 

 grams of the ground leather on a scale that will weigh accurately to 

 1 gram. Place it in a small, dry, close-textured cotton bag which 

 has been washed to remove the starch and other dressing materials 

 from the fabric and which has been given an identifying mark which 

 will not wash out in hot water. Tie securely the mouth of the bag, 

 weigh the bag and leather carefully, and record the weight. Place it 

 in running water as hot as can be readily borne by the hand, and 

 wash out the soluble materials by thorough kneading for 15 minutes. 

 Squeeze out the water and dry over the radiator or in any convenient 

 way until the leather is perfectly dry. Cool and weigh again. The 

 loss in weight represents the amount of soluble matter which has 

 been washed out. This loss in grams, as thus determined directly 

 represents also the percentage loss, and if this exceeds 15 per cent 

 the leather may safely be said to be weighted. 



The following figures show some results actually obtained by this 

 method and also the results obtained in careful analysis of the 

 leather: 



Water-solubh material in leather. 



For practical purposes the results obtained in this way are suf- 

 ficiently accurate. 



BLEACHING OF SOLE LEATHER. 



Leather which has been properly tanned with liquors made from 

 chestnut or rock oak bark has been considered for generations to be 

 the best for shoe soles. This leather has a bright light-oak color, 

 the price which it brings depending very largely on this brightness 

 and uniformity of color. As it comes from the tanning liquors 

 leather is often quite irregular in coloring, and when made from 

 nearly all other vegetable tanning materials it is darker in color than 

 that tanned with oak bark. Irregularity of color is not necessarily 

 a sign of inferiority, but, as a matter of fact, it generally indicates 

 damage done in the preparation, tanning, or finishing of the leather, 

 or stained or damaged places on the original hides. The shoe manu- 

 facturer knowing that uniform color is characteristic of hides prop- 



