USEFUL TO THE MICROSCOPIST 



1109 



Substance 



Monobromonaphthalene 

 Pipeline and Balsam 

 Naphthyl-phenyl-ketone 

 Bromide of Antimony . 

 Pipeline 



Methylene di-iodide 

 Sulphur in methyle 

 Zircon 



Carbonate of Lead 

 BorateofLead . 

 Phosphorus in meth 

 Sulphur (melted) . 

 Phosphorus 

 Diamond (sp. gr. 3-4) 

 Chromate of Lead 

 Eealgar (artificial) 



Glass 



Substance Refractive Index ^ 



Crown n D 1-51 to 1-56 59-0 to 46-0 



Plate /j. D 1-516 



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



Light Flint A* 1'574 41-0 



Dense Flint . A* D 1'622 36-5 



Extra Dense Fluid . A* D 1'650 34-2 



Double Extra Dense Flint A* D 1'710 30-0 



Boro-silicate Crown A 4 1'51 64-0 



Phosphate Crown A* D 1*51 to 1-56 70'0 to 67'0 



Barium Silicate Crown A* 1'54 1-60 59-0 55-0 



Boro-silicate Flint A* D 1*55 1-57 49-0 47'0 



Borate Flint . A* D 1'55 1-68 55-0 33-0 



Barium Phosphate Crown A* D 1'58 65-2 



Very heavy Silicate Flint A* D 1-963 19'7 

 Glass of Antimony . . A* D 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. 



