WEIGHTING OF LEATHER. 11 



hensible form of weighting. It is needless and wastes valuable mate- 

 rials which can be employed in the production of more leather, and it 

 often leads to bleaching or addition of glucose or Epsom salts to con- 

 ceal the injury which frequently results from the presence of excessive 

 quantities of uncombined tanning materials. The elimination of this 

 waste would not only conserve our fast-diminishing native tanning 

 materials, but reduce the quantity imported, and thus help maintain 

 the balance of trade in favor of this country. It is an astonishing 

 fact that practically all the leathers analyzed contain as much uncom- 

 bined tannin as good quality oak or hemlock bark and many contain 

 much more. Inspection of the tables shows that approximately one- 

 third of the tannin in these leathers is uncombined, the quantity 

 varying from 9 to 17 per cent. This is sufficient to tan one-third 

 as much sole leather as is now made. Fully half of this wasted tannin 

 can and should be saved. It is worth approximately $1,000,000 

 and would tan approximately 100,000,000 pounds of leather. This 

 tanning material is now practically a total loss. 



For the past 15 or 20 years energetic efforts have been made to 

 prepare from the waste liquors produced by making paper from wood 

 by the sulphite process products that will tan hides. The woods 

 from which paper pulp is made, with but few exceptions, do not con- 

 tain more than from 2 to 4 per cent of tannin. If this is all removed 

 by the sulphite liquors which are subsequently concentrated to 50 

 per cent solids, the concentrated material offered for tanning purposes 

 can contain at most but 4 or 5 per cent of tannin. Up to the present 

 efforts to make leather with waste sulphite liquors have been crowned, 

 at most, with but indifferent success, and in no case do the makers of 

 these products from sulphite liquors advocate that they be used alone 

 in tanning, but always in mixture with materials of known tanning 

 value. These materials are now receiving careful attention from 

 several sources for determining finally whether they have a proper 

 place in the making of leather. Until such tune as it shall have been 

 shown that these products will make serviceable leather or that they 

 contribute to the desirable qualities of leather they should not be 

 used in commercial tanning. 



DETECTION OF WEIGHTING. 



Although it is not practicable for the ordinary individual to deter- 

 mine whether the leather in shoes has been weighted or loaded, the 

 shoe manufacturer can do so in a very simple way. Large quantities 

 of Epsom salts give leather the characteristic bitter taste of the salts, 

 while glucose in quantity gives the leather a very faint sweetish taste. 



Whether or not leather has been loaded with soluble materials can 

 be readily determined by anyone by the following simple procedure: 

 Grind a sample of the leather (a pair of soles serves well) to a 



