126 ELEMENTARY PHOTOMICROGRAPHY. 



absorbing surplus dye, softening edges, or grading 

 from dark to light tones. Get intensity by repeated 

 washes of diluted colour rather than with full 

 strength, and do not clog details. If slide be too 

 crude or over coloured, soaking in water will 

 remove the excess. 



Compound colours may be obtained by super- 

 posed washes of the component primaries, as, for 

 example, green will be shown by a wash of blue 

 over yellow ; but often the blended tints may be 

 secured by directly mixing the requisite colours. 

 A little practice will enable anyone with a 

 knowledge of water-colour painting to produce 

 creditable results. 



TONING BATHS FOR LANTERN SLIDES. 

 Although a series of good black or rich brown 

 slides would satisfy most tastes, it is occasionally 

 necessary to emphasise some particular point in 

 an object by a suggestion of its natural hue ; and 

 for this purpose various toning baths may be used 

 by which almost any desired colour may be got. 

 A few coloured slides, moreover, judiciously inter- 

 spersed, will be a distinct relief and pleasure to 

 most audiences, especially when the colour helps 

 to convey a more faithful conception of the object 

 than could be done in black and white, and they 

 will prevent the monotony usually attendant on 

 a continuous display of uniform tones. 



