USEFUL TO THE MICROSCOPIST 11 09 



Substance Refractive Index 



Monobromonaphthalene . . . . /j. D 1-658 19'9 



Piperine and Balsam ...... /j. D 1-657 



Naphthyl-phenyl-ketone ..... /j. D 1-669 17'6 



Bromide of Antimony . . (approximately) /u D 1-680 



Piperine ...... " . n D 1-681 9'88 



Methylene di-iodide ...... n D 1-743 21-2 



Sulphur in methylene di-iodide . . . . /x D 1-778 



Zircon ..... . p. D 1-950 



Carbonate of Lead . . /u D 1-81 to 2-08 



Borate of Lead ....... /u A 1-866 



Phosphorus in methylene di-iodide (equal weights) /t D 1-944 17'1 



Sulphur (melted) . ..... '. /* E 2-148 



Phosphorus ...... . ^ D 2-224 



Diamond (sp. gr. 3-4) ...... /j. D 2-47 



Chromate of Lead ...... /u. D 2-50 to 2-97 



Realgar (artificial) ...... /* E 2-549 



Substance Refractive Index 



Crown /j. D 1-51 to 1'56 59'0 to 46-0 



Plate M D 1-516 



Extra Light Flint . . . . ^ D 1-541 49"2 



Light Flint /t D 1-574 41-0 



Dense Flint /J.D 1-622 36-5 



Extra Dense Fluid . . . . /j. D 1-650 34'2 



Double Extra Dense Flint . . . /* D 1-710 30-0 



/Boro-silicate Crown . . . /j. D 1-51 64-0 



Phosphate Crown . . . //. D 1-51 to 1-56 70-0 to 67-0 



Barium Silicate Crown . . ^ D 1-54 1-60 59'0 55-0 



Boro-silicate Flint . . . /J.D 1-55 1-57 49-0 47-0 



Borate Flint . . ./ID 1-55 1-68 55'0 ,. 33-0 



Barium Phosphate Crown . . /* D 1-58 65-2 



Wery heavy Silicate Flint . . /*. i> 1-963 19-7 

 Glass of Antimony . . . ./to 2-216 



The extraordinary dispersion of the alkaloid Piperine will be noticed. Its 

 refractive index is less than that of Chance's Double Extra Dense Flint, yet 

 Piperine has three times its dispersion. 



03 



C 

 o 



1-5 



