1 52 APPENDICES 





Refractive index 



Refractive index 



Oil of cloves 



• 1-530 



Dense flint . . . . 



. 1-650 



Canada balsam . 



. 1-540 



Extra dense flint 



. 1-710 



Styrax .... 



. 1-582 



Jena Glass 



Oil of cassia 



. about 1-626 





Monobromide of naphthaline 



• 1-657 



Boro-silicate crown 



I T 



Piperine .... 



. I -684 



Phosphate crown 



1-51-1-56 



Quinidine . 



. 1-700 



Barum silicate crown . 



I '54- 1 -60 



Phosphorus 



. 2-224 



Boro-silicate flint 



• 1-55 



Eealgar (artificial) 



• 2-549 



Borate flint . . . . 



1-55-1-68 



Diamond .... 



• 2-47 



Barium phosphate crown 



I-57-I-59 



Crown glass 



• 1-51 to 1-53 



Very heavy silicate flint 



1-96 



Plate glass .... 



• 1-516 



Glass of antimony 



. 2-2l6 



Flint 



. 1-54 to 1-62 



(Carpenter 



abridged). 



APPENDIX IX 



TWENTY-FIVE COMMON FAULTS IN PHOTO-MICROGRAPHS: THEIR 



CAUSE AND MEANS OF CURE 



I. A shaded effect over one side of the print i. This is mostly due to the light being un- 



which is not observable on the other. equally spread over the surface. In other 



words, if in a loiv power photograph to the 

 lime not being central. Tn a medium or high 

 power one partly from that source, and also 

 because the auxiliary condenser is not central. 

 Perhaps, too, the substage condenser is out of 

 centering. 



2. This may arise from several causes — ove7-- 

 exposure with ?m6^^r-development ; or not 

 enough bromide in developer. Fogging of the 

 plate before or during development, which may 

 give rise to the idea during development that 

 that process has been carried far enough, and 

 yet in reality is not of sufficieyit duration. 



Light entering the camera during exposure, 

 or whilst the slide is being drawn. See that 

 the exposing shutter acts properly, and that 

 the dark room is sound. Too much soda in 

 the developer will cause much the same effect, 



2. A flat and dull appearance over the whole 

 picture. 



