SECTION II. GENERAL METHODS OF 

 CHROME LEATHER MANUFACTURE 



IT has been previously pointed out that the chrome 

 tannage is an " empty " one ; the primary principle in 

 the wet work of goods for chrome leather is to avoid 

 anything which will make this feature more obvious. In 

 the vegetable tannages relatively larger amounts of the 

 tanning agents are used, and these fill the interfibrillar 

 spaces ; indeed, as we have seen (Part I., Sections III., V. 

 and VI.), effort is made to increase these spaces and to 

 fill them to their maximum capacity, thus yielding a 

 leather of which 50 per cent, is the tanning agent. In 

 chrome tanning, however, the tanning agent may only 

 be approximately 5 per cent, of the finished leather, so 

 that any trouble taken to split the hide fibres or to dissolve 

 hide substance is usually not only superfluous, but also 

 calculated to enhance the " emptiness." The governing 

 principle of all the preparatory processes for chrome 

 tannage is therefore the conservation of hide substance, 

 and this principle determines the modifications of the 

 processes of soaking, liming, and deliming, which are in 

 vogue. Now, in most of these processes there is usually 

 some loss of hide substance, and it is the particular problem 

 of chrome tanning to reduce this loss to a minimum in each 

 stage. Whether the loss of hide substance be due to 

 alkaline or fermentive hydrolysis, or to solation of the hide 

 gel, the effect i* ii HI cased by swelling, and in the wet- 

 work for chrome, therefore, any variations in the degree 

 of swelling are objectionable. The preparatory processes 

 should be carried out with as little change as possible in 



