198 DR. BREWSTER ON REFLECTED LIGHT. 



Image at the 

 Names of Oils. Image at the Surface of Prism A. Surface of Prism B. 



{At a low temperature the orders are scarcely perceptible, "j 

 the second limit only being visible. Heat brings out I ,,t, v- i, n 

 the second limit at a less incidence, and creates the first ^Whitish yellow, 

 limit at 79°. J 



Castor Oil See page 193. 



^•1 oTT f Colours very faint. Heat brings out three good orders. 1 ,^r,.., „ 



Oil of Hyssop.... I First limit at 77°. | Whuish yellow. 



„., ^T^ , f Colours rather better than the preceding. Heat brings 1 ,j(t,;,; , „,,, 



Oil of Fenugreek . . | ^^^ ^j^^^^ g„„j ^^^^^^ ^-^^^ fj,^i^ ^^ fgo. j Whitish yellow. 



Oil of Caraway-seeds Two orders, not good. Whitish yellow. 



Oil of Thyme .... Slight tinges of colour. Heat brings out two good orders. Yellowish white. 

 Oil of Turpentine . Two tolerably good orders. First limit at 74°. Whitish yellow. 



_, . ^., ("Two tolerably good orders. First red bad, second red"! y n • i, y,-f 



Linseed Oil j Two extremely faint orders. Three good orders brought j yellowish white. 



„ . „., f Three very good orders. First red and first blue excel-! -jr „ . , , ^ 



T'-a"»Oil ( lent. pLt limit at 73°. Heat spoils the first order, j Yellowish white. 



r Almost no colours, both images being yellowish, and that"j 

 OilofSavine ....< of B brightest. Heat brings out three orders. First > Yellowish white. 

 L limit at 80°, which a greater heat brings to 75°. J 



r Almost no colours. A sort of bluish gray when cold."! 

 Oil of Pennyroyal .< Heat brings out two good orders when temp, only 90°, >Yellowish white. 

 L but greater heat injures them. J 



Oil of Almonds .. Three tolerable orders. First red bad, second red good. Yellowish white. 



("Gives three and a quarter orders when cold. First limit at 



I about 80° 



1 



Oil of Mace < When the film of the oil begins to crystallize, it displays V- Pretty bright. 



I red, blue, and greenish tints, at the same incidence, in I 

 L different places. J 



r\-\ ec • .. f Very faint colours. Heat brings out three good orders. 1 Yellowish at great 



Oil of Spearmint.. I first limit at about 77°. / incidences. 



Oil of Lemons .... /^hfe fine orders. First Umit at 74°. Heat destroys the! yellowish white. 

 1^ first order. J 



Oil of Dill Seed . . 1^^'° P""-- «>-ders of colours. First limit at 73°. Heatl y^u^^j^ij ^^ite. 

 L improves them. J 



OU of Peppermint . { ^^st order'^^''' ^'"' ""'* ^^°' "'^* '^''*™^' *^'} ^eUowish white. 

 Oil of Rapeseed • • {^7 "[fjjj ^^'""^ °'"^^'^- ^'"' ^™'' ** ^^° "'^^" improved! gj^j^j^ ^^^ 

 Naphtha from Persia Three very good orders. White. 



