270 Of the Propagation of Heat 



of the liquid, or changing any of its properties, by which 

 the manner of its receiving and transporting Heat could 

 be sensibly affected. 



This contrivance was put in execution in the following 

 manner, with complete success. Having provided my- 

 self with a number of glass globes of various sizes, with 

 long cylindrical necks, I chose one which was about two 

 inches in diameter, with a cylindrical neck \ of an inch 

 in diameter and twelve inches long ; and putting into it 

 about half a teaspoonful of yellow amber, in the form 

 of a coarse powder (the pieces, which were irregular in 

 their forms, and transparent, being about the size of 

 mustard-seeds), I poured upon it a certain quantity of 

 distilled water, which was at the temperature of the air in 

 my room (about 60^ F.). 



Finding, as I expected, that the amber remained at the 

 bottom of the globe, I now added to the water as much 

 of a saturated solution of pure vegetable alkali as was 

 sufficient to increase the specific gravity of the water (or 

 rather of the diluted saline solution), till the pieces of 

 amber began to float, and remained apparently motionless 

 in any part of the liquid where they happened to rest. 



As the glass body was not yet as full as I wished, I con- 

 tinued to add more of the alkaline solution and of water, 

 in due proportions, till the globe was full, and also till 

 its cylindrical tube was filled to within about three inches 

 of its end, and then closed it well with a clean cork. 



Havin.g shaken the contents of this glass body well 

 together, I placed it, with its cylindrical tube in a vertical 

 position, on a wooden stand, and left it to repose in quiet, 

 in order to see how long the solid particles of amber 

 (which appeared to be very equally dispersed about in 

 the whole mass of the liquid) would remain suspended. 



