96 



Metallic falts 

 difperfe much. 



Experiments of 

 diluting them 

 till no colour 

 appeared. 



METHOD OF EXAMINING DISPERSIVE POWERS. 



many oils eflbntial and expreffed, and have found the colours 

 in all thefe cafes reverfed. 



By folutions of metallic falts, a great variety of fuch appear- 

 ances may be produced. Moft of thefe compounds have a 

 highly difperfive power ; and many of them may be rendered 

 fufficiently denfe to occafion reverfion, even when applied to 

 flint-glafs. In a more dilute ftate, they may be ufed with 

 crown-glafs, or plate-glafs, to produce the fame effect. And 

 fince, when further diluted by a lefs difperfive medium, they 

 will alio prefent an appearance of colourlefs refraction, we 

 may, by examining the degree of dilution neceffary for that 

 purpofe, compare the difperfive powers of any ingredients 

 contained in them, and may gradually extend our knowledge 

 of this property to the elements of any bodies, however com- 

 pounded. 



As a fpecimen of the method, I have in this way compared a 

 few folutions of metals, and of other fubftances, that were each 

 diluted till the limit of reflection appeared void of colour, when 

 they were in contact with a rectangular piece of plate-glafs ; 

 and, in the table which follows, I have expreffed their refractive 

 powers in that flate of dilution, as nearly as the eye can difcern 

 the difappearance of colour. 



TABLE II. 



Table of their 

 tienfitics in that 

 ftate. 



Nitro-muriate of gold 



Nitro-muriate of platina 



Nitrate of iron - 



Sulphuret of potalh 



Red muriate of iron 



Nitrate of magnefia 



Nitric acid - 



Nitrate of jargon 



Balfam of Tolu - 



Acite of litharge (extract of lead) 



Nitrate of filver 



Nitrate of copper 



Oil of faffafras - 



Muriate of antimony 



Nitrate of lime - 



Nitrate of zinc 



Green muriate of iron 



Muriate of magnefia 



of lime »• . - 



of zinc - • - 



Elfence of lemon - 

 Balfam of capivi - 



In Water. 

 1,364 

 J, 370 

 1,375 

 1,375 

 1,3S5 



1,395 



1,400 



1,410 



1,415 



1,416 

 1,425 

 1,425 



In Alcohol. 

 1,390 



1,400 



1,405 

 1,410 

 1,422 



1,440 



1,430 

 1,440 



u 



