PURPLE DYE. 167 



ed its first freshness and beauty. The reason assigned for this 

 is, that the purple wool was combed with honey and the white 

 with white oil.* 



The wool thus dyed was so costly that, in the time of Au- 

 gustus, each pound of it sold for 1000 Roman denarii, (about 

 L. 36 Sterling). 



The art of dyeing this colour came at last to be practised on- 

 ly by a few individuals, maintained by the emperors for that pur- 

 pose. It was interrupted about the beginning of the twelfth 

 century, and all knowledge of it was lost. But in the year 1683, 

 Mr Cole of Bristol, being told that a person at a sea-port in Ire- 

 land gained a living by marking linen with a red coloured dye 

 stuff, was induced to make inquiry into his mode of proceed- 

 ing. He found that the individual in question made use of a 

 white liquor in the head of the Buccinum lapillus of LinnaBus ; 

 a shell very common on our coasts. 



Mr Cole procured this liquor from the fish, and stained linen 

 with it. When exposed to the light of the sun the stain be- 

 came first green, then blue, and finally a purple red.f 



These experiments of Cole were afterwards repeated success- 

 fully by M. Jussieu, M. Reaumur, and M. Duhamel. They ob- 

 served the same succession of colours. And they mention also 

 a fetid smell like a mixture of garlic and assafoetida, given out 

 while it was changing its colours. This smell had been also no- 

 ticed by Cole. As no experiments on this curious liquid have 

 been made by modern chemists, we are still ignorant of its nature 

 and properties. I have mentioned it here merely to draw the 

 attention of such chemists as, living upon the sea-coast, may have 

 it in their power to procure the shell fish that yield it. 



CLASS V. 



OF ANIMAL AMIDES. 



THE substances included under this name constitute a very 

 important portion of the materials of which animal bodies are 

 composed. They are still so imperfectly known that we do not 



* Langhorne's Plutarch, ix, 373. f Phil. Trans, xv. 1278. 



