396 1-062 



395 1-090 



396 1-450 



406 1-480 



440 1*840 



92 EXPERIMENTS OF BREWSTER. 



Refractive power. Specific gravity. 



Acetic Acid 



Malic Acid 



Nitrous Acid 



Nitric Acid , 



Sulphuric Acid 



Phosphoric Acid 1-544 2-687 



Rock Salt 1-557 2-600 



Quartz 1-548 2-600 



Garnet 1-515 4-000 



CalcSpar 1-665 2-700 



Aragonite 1-693 2-900 



Sapphire, blue 1-794 4-200 



Arsenic 1-811 5-800 



Calomel 1-970 7-200 



Carbonate of Lead 2-084 6-400 



Sulphur, native 2-038 2-033 



melted 2-148 1-990 



Phosphorus 2-224 1-770 



Diamond.. 2-470 3-591 



Chromate of Lead 2-926 6-000 



Mercury 5*000* 13-500 



* The refractive power of mercury was determined by M. 

 Arago from its power of reflecting light, in accordance with the 

 hypothesis of Newton that both are owing to the same cause, 

 and that the one is a measure of the other. Should this hypo- 

 thesis be well founded, we have an easy method of ascertaining the 

 refractive power of solid and opaque bodies. That M. Arago has 

 very closely approximated the truth in regard to mercury, would 

 appear from the high refractive power of calomel, as determined 

 by Brewster. And that it is nearly the same in lead as in mer- 

 cury, would appear from the high refractive power of its com- 

 pounds, as in the carbonate and chromate of lead ; while it 

 is well known that gold, platinum, silver, iron, tin, zinc, and 

 other dense metals, reflect a much larger proportion of light, 

 (when smoothly polished,) than the same surface of rocks, gems, 

 glass, or the lighter metals ; and the latter more than water, alco- 

 hol, sether, or the oils. It would, therefore, appear that the 

 denser metals contain from two to four times more caloric around 

 their particles than an equal bulk of water, but very much less 



