CHANGE OF COLOUR IN CLOTHES. 385 



colouring matter is visible. Feats of this kind are too 

 common and too generally known to require to be noticed 

 in a work like this. The art of producing such changes 

 was known to some of the early impostors, who endea- 

 voured to obtain a miraculous sanction to their particular 

 dogmas. Marcos, the head of one of the sects that wished 

 to engraft paganism upon Christianity, is said to have 

 filled three transparent glasses with white wine, and while 

 ho prayed, the wine in one of the glasses became red like 

 blood, that in another became purple, and that in the third 

 sky-blue. Such transformations present no difficulty to 

 the chemist. There are several fluids, such as some of the 

 coloured juices of plants, which change their colour 

 rapidly and without any additional ingredient ; and in 

 other cases, there would be no difficulty in making addi- 

 tions to fluids, which should produce a change of colour at 

 any required instant. 



A very remarkable experiment of an analogous nature 

 has been publicly exhibited in modern times. Professor 

 Beyruss, who lived at the court of the Duke of Brunswick, 

 one day pronounced to his highness that the dress which 

 he wore should during dinner become red ; and the change 

 actually took place to the astonishment of the prince and 

 the rest of his guests. M. Vogel, who has recorded this 

 curious fact, has not divulged the secret of the German 

 chemist ; but he observes, that, if we pour lime-water into 

 the juice of beet-root, we shall obtain a colourless liquid ; 

 and that a piece of white cloth dipped in this liquid and 

 dried rapidly will in a few hours become red by the mere 

 contact of air. M. Vogel is also of opinion that this 

 singular effect would be accelerated in an apartment where 

 champagne or other fluids charged with carbonic acid are 

 poured out in abundance. 



Among the wonders of chemistry we must number the 

 remarkable effects produced upon the human frame by the 



