in Fluids, 397 



specting radiant Heat, — which would take up more time 

 than I am at present able to bestow on it. Perhaps I 

 may find leisure and courage at some future period to 

 attempt that most difficult investigation. My reader 

 will doubtless have observed that I have hitherto taken 

 pains to avoid it. 



I cannot take my leave of the experiment I have been 

 describing without giving my reader a faithful account 

 of everything I can recollect respecting it, and particu- 

 larly of one accidental circumstance, which it is possible 

 may have had some share in producing the interesting 

 appearances which so powerfully attracted my attention. 



The saline liquor and the pulverized amber were 

 mixed in a bottle, and were not put into the flat box till 

 after it had been fixed in the sash or frame of the win- 

 dow, but when I came to pour this mixture into the box 

 I found that I had not provided enough of it. To sup- 

 ply this defect, without the trouble of emptying the box, 

 I added, at several different times, pure water, and a 

 strong solution of potash, in such proportions as I knew 

 to be proper to produce the specific gravity required, 

 and then endeavoured to mix the whole as intimately as 

 possible by agitating the liquor for some considerable 

 time by means of a long and strong quill, the end of 

 which I thrust down into the box through the hole by 

 which the liquor was introduced. 



Whether those different portions of liquor were in fact 

 intimately mingled by these means I cannot positively 

 determine. They certainly had every appearance of being 

 so ; for the amber was evidently well mixed, and very 

 equally distributed in every part of the Fluid. But 

 even should we grant that the liquid remained divided in 

 different strata^ arranged according to the specific gravities 



