592 



Frofessor H. E. Boscoe 



[May 27, 



steaming at high pressure. For this reason, only such steam colours 

 can be associated with proi)iolic acid as may be fixed by short steaming 

 at low pressure. 



No. II. — On Prepared Cloth (for Full Shades). 

 Dissolve 2 lb. of xanthate of soda in 1 gallon of cold water. 



Pad 



the goods with the above ; dry, print with standard, and after printing 

 follow the above treatment. The pieces may also be first printed 

 with xanthate and then covered with standard. Alumina and iron 

 mordants for madder colours may be likewise printed on cloth thus 

 prepared, or printed with xanthate of soda. 



The potential importance, from a purely commercial point of view, 

 of the manufacture, may be judged of by reference to the following 

 statistics, showing that the annual value of the world's growth of 

 indigo is no less than four millions sterling. 



How far the artificial will drive out the natural colouring matter 

 from the market cannot, as has been said, be foreseen. It is interest- 

 ing, as the only instance of the kind on record, to cast a glance at 

 the history of the production of the first of the artificial vegetable 

 colouring matters, alizarin. In this case the increase in the 

 quantity produced since its discovery in 1869 has been enormous, 

 such indeed that the artificial colour has now entirely superseded the 

 natural one, to the almost complete annihilation of the growth of 

 madder-root. It appears that whilst for the ten years immediately 

 preceding 1869 the average value of the annual imports of madder-root 

 was over one million sterling, the imports of the same material during 

 last year (1880) amounted only to 24,000/. The whole difference being 

 made up by the introduction of artificial alizarin. In 1868, no less 

 a quantity than 60,000 tons of madder-root were sent into the market, 

 this containing 600,000 kilos, of pure natural alizarin. But in ten 

 years later a quantity of artificial alizarin more than equal to the above 



