OIL TANNAGES 183 



liquored with cod oil and soft soap, machine sammed, either 

 by a wringer or a centrifuge, and then dried out. 



Much chamois leather is also made in France by closely 

 similar methods. The skins are usually oiled on tables and 

 folded up before stocking. Other marine oils (seal, whale, 

 etc.) replace cod oil. Generally speaking the oxidation is 

 more moderate, and the grease from the hydraulic press 

 (moellori) is mixed with other fish oils to form commercial 

 degras. An inferior quality of degras is obtained by subse- 

 quent treatment with soda. 



The crust chamois obtained as above has only to be 

 thoroughly staked to soften, " grounded " and " fluffed " 

 to raise the nap, and then trimmed, and the ordinary wash- 

 leather is obtained. 



If intended for glove leathers superior skins are selected. 

 These are fluffed carefully upon emery wheels, using first 

 a coarse surface and eventually a fine surface so that a fine 

 velvet effect is attained. The skins are next bleached. 



In the " sun bleach " or " grass bleach " the goods are 

 soaked in a i| per cent, soft soap solution and exposed to 

 sunlight after being wrung. They are bleached in about 

 3 days in summer, but nearly a fortnight may be necessary 

 in winter. 



In the permanganate bleach, which is less tedious, the 

 skins are first degreased by soaking in a warm f per cent, 

 solution of soda crystals and then drumming for 30 minutes 

 in water at 95 F. They are then paddled in a J per cent, 

 solution of commercial permanganate for an hour at the same 

 temperature, rinsed through water, and the brown manganese 

 dioxide is then removed by paddling or drumming the goods 

 in a 3 per cent, solution of sodium bisulphite to which 

 hydrochloric acid is added as required. The goods are 

 well washed in warm water, and are then " tucked," i.e. 

 placed in a vat of boiling water containing a little soft soap, 

 just for a few seconds. The goods shrink and curl up, and 

 they are then dried out at I2O-I40 F. to fix the tuck. 

 They are then staked, fluffed, and dyed. 



In dyeing with coal tar colours the alizarin colours may 



