94 An Inquiry concerning the 



The contents of the phial B, which were at first of a 

 light straw colour, first changed to a light green and 

 then to a greenish blue. The phial having been suf- 

 fered to stand quiet several days, in an uninhabited 

 room, in a retired part of the house, the solution be- 

 came nearly colourless, and the sediment was found 

 to be of a dirty olive colour. 



The colour of the contents of the phials C and D 

 was changed nearly in the same manner; and having 

 been suffered to stand quiet two or three days to settle, 

 the solution was found to be quite colourless, and the 

 sediment to be deeply coloured. There was, however, a 

 very remarkable difference in the hues of the contents 

 of the two phials ; that of the phial C being of a light 

 greenish blue, while that in the phial D was indigo, 

 and of so deep a tint that it might easily have been 

 taken for black. 



These appearances were certainly very striking, and 

 well calculated to excite curiosity. I wish that what I 

 have done may induce others to pursue these interest- 

 ing investigations. 



