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TUESDAY, DECEMBER 7th. 



W. Webstee, Jun., Esq., F.C.S., gave a Lecture on " Dyeing." 

 The art of dyeing has been practised in the East Indies, Persia, 

 Egypt, and Syria, for centuries. In the Pentateuch, frequent 

 mention is made of cloths dyed blue, purple, and scarlet, and of 

 rams' skins dyed red. The vestments of the High Priests were 

 purple. The Tyrians were the only people of antiquity who made 

 dyed goods their staple of commerce. An inhabitant of Tyre 

 discovered the pm-ple dye 1500 B.C., and, it is believed, extracted it 

 from a shell-fish. The colouring matter when taken from the animal, 

 by exposure to the air and light, became successively citron-yellow, 

 green, azure, red, and, in the course of forty-eight hours, brilliant 

 pm-ple. It is unknown how the colour was obtained, and no attempts 

 to manufacture the dye now-a-days have been successful :— it is a 



lost art. 



Objects which appear coloured have no colour in themselves. 

 The appearance of colom- is due to the reflection of certain of the 

 constituents of white light, and annihilation or absorption of the 

 rest. The Lecturer exposed ribbons, which by white light appeared 

 of various hues, to the yellow light of buraing sodium, and it was seen 

 that the yellows were very distinct, while the other tints looked black, 

 owing to the absence of those rays which are necessary for the 

 production of their special colours. 



The processes of dyeing consist in staining textile fabrics so that 

 the colour impai-ted to them is rendered insoluble in water. Cotton, 

 wool, and silk are the chief substances which are operated upon by 

 the dyer, and they require some little preparation before they can 

 take the colour to be imparted to them. Cotton goods are 

 prepared by boiling them in water for two or three hours, 

 while woollen materials are steeped in soap lye or alkaline solutions 

 to remove all oily and greasy matter. Silk is also boiled in a strong 

 soap solution to remove the gummy substances found upon the 

 surface of its fibres. 



Few colours have any dii-ect affinity for cotton or other goods ; 

 if they had. dyeing would be a very simple affair: for it would 



