10 LEATHER INVESTIGATIONS: SOLE LEATHERS. 



temporary advantage, because the slowly soluble tannins make the 

 leather more water resistant and impede the removal of combined 

 tannin from the leather. 



QUANTITY OF ADDED WEIGHTING MATERIALS. 



The amounts of materials found in the loaded leathers examined 

 are summarized as follows: Ash, from 0.2 to 2.7 per cent; ether 

 extract, from 0.4 to 5.6 per cent; Epsom salts, from 0.2 to 7.5 per 

 cent; glucose, from 0.2 to 12.4 per cent; water-soluble materials, from 

 13.4 to 34.3 per cent; water-soluble tannin, from 6.1 to 17.8 per cent. 



If it is feasible to secure the lower figures, as it appears to be in a 

 number of tanneries, the higher figures must represent very excessive 

 quantities. A comparison of these, together with those in the table 

 on pages 16 to 20, with the figures given for normal leathers shows that 

 the percentages of ash, Epsom salts, glucose, and water-soluble mate- 

 rials are, as a rule, above the permissible quantities, while the amounts 

 of fats and oils and actual leather substance are lower than they 

 should be. These figures show a serious moral, economic, and busi- 

 ness condition. Approximately 63 per cent of the leathers examined 

 are weighted with glucose, Epsom salts, or both. This loading varies 

 from 1 to 7.5, with an average of 3, per cent of Epsom salts, and up to 

 10.4, with an average of 5.5, per cent of glucose, and amounts to a 

 total maximum loading, when both are present, of 16 per cent and an 

 average of 8 per cent. 



WASTE OF MATERIALS IN WEIGHTING SOLE LEATHER. 



The tanners whose leathers have been examined produce a large 

 percentage of the sole leather made in this country. It seems prob- 

 able, therefore, that these samples are fairly representative of Amer- 

 ican sole leather, and if this be true fully 60 per cent of the sole 

 leather is loaded with Epsom salts or glucose or both, and practically 

 all of it contains more uncombined tanning materials than it should. 

 , If 60 per cent of the sole leather contains an average of 8 per cent 

 of Epsom salts and glucose, at least 150,000,000 pounds have been 

 weighted annually with no improvement in its wearing value. The 

 people have paid for not less than 12,000,000 pounds of Epsom salts 

 and glucose, plus a profit to the tanner for working them into the 

 leather, and have obtained nothing of value thereby. The average 

 amount of water-soluble material in these sole leathers is 23 per 

 cent. Subtracting from this the average percentage of glucose and 

 Epsom salts found gives the percentage of what for brevity may be 

 called " uncombined tanning'' materials, meaning the materials 

 derived from the tanning liquors in which the leather was tanned. 



The almost universal practice of weighting or loading with excessive 

 quantities of uncombined tanning materials is perhaps the most repre- 



