220 Dr Brewster on the rejlection and decomposition of 



Image at the Surface of Prism A. 



Oil of Sweet Fennel-seeds. — Two or- 

 ders ; pink good. 



Wood Oil. — Three good orders of co- 

 lours. First pink and blue fine. First 

 limit of pink and blue ends at QB° 



Oil of Amber. — Two excellent orders of 

 colours. First limit of pink and blue 

 at Q5°. Improved by heat. 



Oil of Rhodium. — Two and a-half good 

 periods. First limit at Q5°. Heat in- 

 jures them. 



Treacle, — At temp. 50° three orders, 

 which are not good, especially the 

 pink of first and blue of second order. 

 Heat brings out three splendid orders 

 with periods, as in castor oil. * 



Balsam of Sulphur. — Three fine orders. 

 First limit of pink and blue at about 

 67°. 



Honey. — Two pretty good orders. First 

 limit at about Q5°. 



Oil of Angelica. — Two and a-half or- 

 ders. First pink and first blue fine ; 

 second red good. 



Oil of Nutmeg. — Three not very bright 

 orders. First limit at 73°. 



Oil of Marjoram. — At a low tempera- 

 ture the orders are scarcely percep- 

 tible, the second limit only being vi- 

 sible. Heat brings out the second li- 

 mit at a less incidence, and creates 

 the first Hmit at 79°. 



Castor Oil. — See page ^12. 



Oil of Hyssop. — Colours very faint. 

 Heat brings out three good orders. 

 First limit at 77°. 



Image at the 

 Surface of Prism B. 

 Bluish gray. 



Bluish 



gray, 



weak- 



mci- 



er at great 

 dences. 

 Pale blue, very faint 

 at great incidences. 



Yellowish white. 



Yellowish white. 



Faint gray, getting 

 fainter and bluer 

 at great incidences. 



Slightly yellowish 

 white. 



Whitish yellow. 



Whitish yellow. 



Whitish yellow. 



Whitish yellow. 



* The treacle used in this experiment is much inferior in refractive 

 power to the prism A. 



