Permanent Colours of Opake Bodies, 165 



to this inconvenience, may be conflantly kept in 

 the vials. 



The uncovered fide of the vial fliould not be 

 placed oppofice to the window, through which 

 the light is admitted j becaufe in that fituatioa 

 the light would be refle6led from the farther fide 

 of the vial, and would be tranfmitted through 

 the coloured liquor; and it is obfervable that 

 fmooth black furfaces refledt light very power- 

 fully. Now as it is a principal objecft in the 

 experiment that no light be tranfmitted through 

 the liquors, this will be accomplifhed by placing 

 the uncovered fide of the vial in fuch a dire6tion, 

 that it may form a right angle with the window. 



I have examined a great variety of Tranfparent 

 Coloured Liquors, in vials, prepared and difpofed 

 as I have here defcribed, and have conftantly 

 found that in every inftance, that part of the 

 liquor, which was contained in the neck of the 

 vials, exhibited its colour diftinftly and vividly; 

 but, that portion, which was in the body of the 

 vials, and which was viewed through the un- 

 covered fide, exhibited no colour ^ but was black. 



From amongfl: numerous fimilar obfervations, 

 I have felefted thofe which are fet down in the 

 following table: I have not attempted therein 

 to produce any regular or fyftematical collefVion 

 of coloured liquors, but only to exhibit fuch 

 fpecimens as may ferve to fliew the aclion of 



M J vegetable. 



