WOOL 



49 



fibre or the end of the staples. This prevents the dye from 

 gaining free access to the medulla, the consequence being that 

 you cannot obtain from pulled wools the full rich colours 

 which shorn wools give. Wool will resist most acids but will 

 dissolve if subjected to strong alkalies such as caustic soda. 

 You can completely dissolve wool by boiling it in a 10 per 

 cent, solution of caustic soda. Silk is another animal fibre 

 which will dissolve in strong alkali solution. Cotton and all 

 material made of vegetable fibre will resist the action of 



12 34 



[Photo by An tli or. 



1. Cloth made up of wool and cotton. 



2. Same cloth with wool removed by immersing in caustic solution. 



3. Wool cloth with white cotton yarn running through it. 



. 4. Wool removed as before, showing quantity of cotton left. 



alkalies. Cloth can be tested to see whether it is all wool, 

 or a mixture of both wool and cotton, or any other vegetable 

 fibre, by immersing it in a strong solution of caustic soda 

 for a couple of minutes a dessert-spoonful in a breakfastcup 

 of very hot water. This caustic solution will completely 

 dissolve all the wool, and if the piece of cloth tested is made 

 of pure wool without any cotton or other vegetable fibres 

 mixed through it, it should dissolve completely, just a very 

 small and slimy solution being left in the bottom of the cup. 



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