PRACTICAL PHOTOMICROGRAPHY. 107 



Obernetter. The best color-correct plates for photo-microg- 

 raphy we have ever used were produced by Mr. Edwards for 

 copying purposes. Where sensitiveness to certain regions of 

 the red is required, the " azaline " plates of Obernetter are, 

 perhaps, the best in the market ; but " cyanin"-stained plates 

 are the best of all for reds. 



The photo-micrographer who has time and a good drying 

 cupboard may quite easily orthochromatize his own plates. 

 An emulsion should be chosen capable of giving ample 

 density, not very rapid, and not containing more than 3 

 parts of iodide to 100 of bromide. The writer has tried, per- 

 haps, every published process of any promise for " staining " 

 his plates, but finds none so simple or so effective as a process 

 lately promulgated by the talented Mr. Ives, of Philadelphia. 

 The dyes suggested by Mr. Ives are erythrosin and cyanin. 

 The latter seems to sensitize for reds more than any aniline 

 we have tried, but the operations must be carried out prac- 

 tically in total darkness. The erythrosin or cyanin may be 

 used as follows : 



Take of the dye 1 grain 



Absolute alcohol 4 ounces 



. Soak the plate in this for one minute, allow to dry in total 

 darkness. This will not take long. Then place the plate 

 face upwards in a black tray and cover the tray with another 

 tray or flat cover having a hole in the top into which is let a 

 piece of tubing. Connect the tubing with the water tap and 

 wash the plate in the covered tray for five to ten minutes. 

 In very subdued red light, or in darkness, convey the plate to 

 the drying press ; when dry it is ready for use. The drying- 

 box or press must be properly constructed for passing a con- 

 stant current of dry air ; details of such presses will be found 

 in " The Processes of Pure Photography " (Scovill & Adams 

 Company). 



A book as long as the whole of this one would be required 

 to do full justice to the processes of color-correct photography. 

 We have to allow for such wide variations of color, and there 

 are so many different methods available for meeting our various 



