I Permanent Colours of Opake Bodies', 187 



affinity with the phlogifton which the fulphurhad 

 communicated, they unite with that principle, and 

 difengage it from the colouring particles; which, 

 being thus extricated, refume their original mag- 

 nitude, and colour. 



Fixed alcali, whofe affinity alfo with phlogifton 

 is very great, changes the whitened flowers to 

 purple, blue, and green, which colours alcali al- 

 ways produces in fuch flowers. 



The matter of light ads upon coloured bodies, 

 in the fame manner as the phlogiftic vapours, 

 ■whofe operations have been here explained. Thus 

 dyed filk, or other fl:ufFs, expofcd to the fun's light, 

 are deprived of their colour, in every part, which 

 lies in the diredion of the rays, whilft thofe parts 

 preferve their colour, which are defended from 

 the accefs of the rays by their folds, or by the 

 intervention of any opake body which intercepts 

 the light. 



The colours, thus impaired by the adion of 

 phlogiflon or of light, may be reftored by the 

 means already defcribed, if they are applied whilft 

 the folution of the colouring particles is recent : 

 but, afterward they are apt to fly off', and be en- 

 tirely diffipated, on account of the volatility, 

 which the inflammable principle confl:antly im- 

 parts to matter, with which it is united. 



The adion and properties of phlogifton, and of 

 ;he fun's light, are fo exadly fimilar, that the 



identity 



