hy transmissioti through Fluids. 427 



must be had to its effects upon the yellow ray, which may be 

 easily ascertained by observing the appearance of O previous 

 to the introduction of the circularly polarizing medium. 



The following general conclusions will be easily understood 

 from the Tables. 



That, whether the rotation be right- or /^//-handed, the 

 urder of succession of colours is the same in X as it is in O, 

 the one lagging as it were 90^ behind the other. 



If the analyser be revolved so as to obtain what may be 

 termed a descending succession of colours, viz. red, orange, 

 yellow, green, blue, &c., the direction in which it is revolved 

 coyTesponds to that of rotation. 



If the analyser be revolved to the right-hand, when exa- 

 mining a substance possessed of /^-handed rotation, the 

 order will be in what may be termed an ascending scale, viz. 

 blue, green, yellow, orange, red. 



If in examining a substance possessed of n^/;/-handed rota- 

 tion the analyser be turned to the left^ the order will also be 

 in an ascending scale, viz. blue, green, yellow, orange, red, &c. 



That, *isohether the rotation be right or left^ provided the 

 amount is alike, X and O will exhibit the same tints at a si- 

 milar number of degrees of rotation marked in the right- or 

 left-handed circles of graduation respectively. 



Hence, at the points of greatest obscuration, there is no dif- 

 ference in the appearances exhibited, whether the rotation be 

 right- or /^if-handed. 



That X assumes the tint of O, and O that of X at an exact 

 interval of 90°. 



That with a double refracting analyser each particular tint 



