CATALOGUE. PlirsiCAL OPTICS. 



259 



Plate glass, English. W. 

 Glass of St. Gobln. r.1.543. 1.49 



Crown glass. W. 



Crown glass, r. 1.532. 1-48 



Solution of sul ammoniac, r.1.382. 1.34 

 Ilwby, spinelle. W, 



Saturated solution of salt. r. 1.375. 1.22 

 Water. VV. - - 1.00 



Sulfuric acid. W. 

 Alcohol. W. 

 Sulfate of barytes. W. 

 Selenite. W. 

 Rock crystal. W. 



Rock crystal. r.l.5fiO. (^1.21 



1.5'75. ^ 1.24 



Sulfate of potash. W. 

 White sapphire. W. 

 Fluor spar. W. 



It is obvious, that many of the results of these obsenra- 

 tions cannot be reconciled; and it is probable, that the num- 

 bers are frequently inaccurate. 



Wollaston's Table of the Refractive Powers 

 of solutions equal in Dispersive Powers to 

 Plate Glass. 



In water. In alcohol. 

 Nitroniuriate of gold. 1.364 1.390 

 Nitromuriate of platina. 

 Nitrate of iron. 



Sulfuret of potash. 

 Red muriate of iron. 

 Nitrate of magnesia. 

 Nitric acid. 

 Nitrate of jargon. 

 Balsam of Tolu 

 Acetite of litharge. 

 Nitrate of silver. 

 Nitrate of cop'per. 

 Oil of sassafras 

 Muriate of antimony 

 Nitrate of lime 

 Nitrate of zinc 



1.370 

 1.375 



1.375 

 1.385 



1.395 



1.400 



1.410 



1.400 



1.405 

 1.410 



1.422 



In water, |nalcohol. 

 Green muriate of iron 1.415 

 Muriate of magnesia 1.416 

 Essence of lemojx - 1 .430 



Muriate of lime 1 .425 1 .440 



Muriate of zinc 1.425 



Balsam of capivi - 1.440 



Hence it seems to follow, that the dispersion of the nitric 

 acid is a fourth more than that of plate glass : a dispropor- 

 tion much greater than appears in the numbers of CaTaUo'a 

 table. 



With crown glass the nitric acid was diluted to l.3?5, 

 and the muriatic from 1.39 to i.sga. 



Ordinary Atmospheric Refraction, Cekstia 

 or Terrestrial. 



See Meteorology, to which this subject partlj 

 belongs. 



Refractio solis inoccidui. See Irregular 

 Refraction. 



Cassini on refraction. Bologn. 1672. 

 Ace. Ph. tr. 1672. VII. 500. 



Cassini on refractions. A. P. I. 103. 1700. 

 39. H. 112. 1714. 33. H. 61. 1742. 203. 

 H. 72. 1743. 249. H. 140. 



Cassini on tlie dip. A. P. VIII. 71. 1707. 

 195. H. 89. 



Lahireon the atmospheric refraction at Tou- 

 lon. A. P. VII. i. 174. 



fLahire on the path of light in the atmo- 

 sphere. A. P. 1702. 32. 182. H. 54. 



Laval on refractions. A. P. 1708. H. 105.. 

 1710. H. 109. 



Delisle on the refraction of the air. A. P. 

 1719. 330. H. 71. 



Halley on atmospherical refraction, -with 

 Newton's table. Ph. tr. 1721. XXXI. 

 169. 



Taylor Methodus incrementorum. 



Bouguer on refraction in the torrid zone. 

 A. P. 1739. 407. H. 45. 1749. 75. H. 152. 



Mairan on the refraction of the air. A. P. 

 1740. 32. H. 89. 





