Mr. Delaval on the Caiije^ ^c, 147 



^n Experimental Inquiry into /Z;^ Cause of the 

 Permanent Colours of Opake Bodies. By 

 Edward Hussey Delaval, F. R. S. of the 

 Royal Societies o/Upsal, and Gottingen, 

 of the Institute of Bologna, and of the 

 Literary and Philosophical Society of 

 Manchester. Communicated hy Mr, Charles 

 1'aylor, Read May i^^ 17S4. 



T^HE chief defign of this inquiry is, to in- 

 -^ veftigate the nature, origin, and caufe, 

 of the permanent colours of opake bodies. 



I was led to the purfuit of it, from a perfuafion 

 of its utility, to thofe interefting and elegant 

 Arts, whofe objeft is the preparation, and ufe, 

 of colouring fubllances. 



The difcovery of this principle is the foun- 

 dation, on which alone all the parts and mate- 

 rials of the knowledge, relative to thofe Arts, 

 can be raifed and fupported. 



It lliould be the office of experimental philo- 

 fopiiy, to examine the powers and properties of 

 all the materials, requifice to technical ufes. 

 Nor fhould its views be confined to the theories, 

 which refult from thofe refearches, but direded 

 to the praftical application of them. 



L 2 III 



