* The Stanley dry plate has all these qualities in the highest perfection.
A carefully kept note-book is a most important aid to the worker in photo-micrography, and it should contain all his failures and successes alike. Notes should be made of the specimen objective, magnification, exposure, plate and developer, which, carefully studied, will almost certainly enable him to secure a success with each exposure.
It is well to make the negative as far as possible of a suitable size for producing the positive by contact printing, which is convenient and satisfactory, though there can be no doubt that reproduction in the camera affords better results. Slow gelatino bromide plates, such as Carbutt makes for this purpose, produce very satisfactory work, but the chlorides are so far superior that there can be little doubt of their being exclusively employed for positives in future. There is a richness of tone, combined with great transparency in the shadows and clear glass in the high lights, quite unattainable with bromide emulsions, and rivaling the best wet work.
These may be photographed by the light from a lamp quite as well as transparent ones, through which the light is thrown, a matter of which I have thus far spoken, only. A strong illumination must be obtained by the employment of a suitable bull's-eye condenser or a silvered reflector. The most satisfactory method, however, is by sunlight, allowing its direct rays to fall upon the object without the intervention of any condenser whatever. Very short exposures suffice with such illumination, varied only by the reflecting capacities of the object itself. A successfully exposed plate of this class of objects will give a print of the subject, standing out most brilliantly upon a black ground.
To secure the best results, most objects should be specially mounted for photographing. Some are best in a resinous medium, such as Canada Balsam, but most tissues are obscured or entirely obliterated in this medium. So far as possible all preparations should be mounted in a fluid of some description that will distinctly render visible many tissues and markings which would be lost in balsam. This subject, however, is one of so great extent that it would require a special paper, and I merely refer to it now because of its importance, hoping at some future time to enlarge more fully upon it.
You will notice that my remarks have been confined to work that may be done with objectives of low or moderately high powers, in no case exceeding one thousand diameters, having preferred to speak only of that which I have demonstrated by actual work as being practical. From recent experiments I am fully convinced that the lamp light, such as I have described, is capable of producing satisfaction, work with very much higher powers, and shall hope, at no distant day, to" show prints made from magnification of not less than two thousand diameters, that will be satisfactory in all respects.
W. H. Wamsley.