Journal : Journal of cutaneous and genito-urinary diseases, vol. vi.
New York : William Wood, 1888.
Description : pages 41-43.
Subject : Cutaneous photography.
THE desirability of keeping a permanent pictorial record of important and interesting cases of cutaneous disease is fully appreciated by every working dermatologist; but thus far the difficulties in the way of giving this practical effect have been so great that comparatively few pictures have been taken except by those who have given the matter special attention.
The chief obstacle has been the difficulty of securing in the consulting-room a sufficient and a proper distribution of the light, making it necessary in most cases to take the patient to the operating rooms of the professional photographer. To this many patients object. Even when they consent, an hour's time is lost for each negative secured.
My purpose this evening is to bring to your notice a simple method, devised by myself, whereby these inconveniences may be reduced to the minimum. The method referred to relates to the illumination of the subject, and not to any special construction of the photographic apparatus.
In my own office if diffused sunlight be used on a bright day, an exposure of thirty to sixty seconds has often been necessary ; but with the new method equally good pictures may be taken in the night or in a darkened room in a fraction of a second. This is brought about by the use of an artificial light produced by the instantaneous combustion of magnesium powder. This gives a momentary flash of light of surprising brilliance and amply sufficient for the purpose.
Magnesium by itself will not ignite or burn as rapidly as when in contact with some more easily inflammable substance, and I find by experiment that ordinary photographer's pyroxylin, or gun-cotton, is admirably adapted to the purpose in view.
The magnesium and cotton are arranged for use in the following manner: A tuft of cotton weighing about seven or eight grains is spread out as a thin layer on any metallic surface, as a stone-lid or tin plate. Ten or twelve grains of magnesium powder is next sprinkled evenly over the cotton.
The patient is then brought into position and the focus obtained in the usual manner. If in the day time, daylight may be used for focussing, but if at night or in a darkened room, a candle or lamp held near the patient will answer as well.
The cotton-magnesium is now adjusted or held by the side of the camera and slightly in advance of the lens, care being taken not to bring it within the view angle of the lens. The plate holder is then affixed to the camera and the slide withdrawn. The room is then absolutely darkened, and the lens is uncapped. All being now ready, a lighted taper is applied to the cotton. This is followed by an instant flash which takes the picture. The lens is capped, the slide of the plate-holder is returned to its place, and the plate is ready for development, either by the operator if sufficiently skilled, or by a professional photographer, if desired.
Since my first publication of this instantaneous flash process, a large number of substitutes for the cotton magnesium combination have appeared. These are all in powder form and many of them contain chloride of potassium as an ingredient. Such mixtures are liable to premature and unexpected explosion and are not to be recommended when absolute safety is a desideratum.2 Care, therefore, should be taken to obtain a mixture entirely free from this objectionable substance.
When a full-length figure is to be taken, in order to show the generalization of an eruption, I am in the habit of using the photogenic mixture in a pistol cartridge, and firing it from the weapon in the usual manner.
As regards the photographic apparatus available for office photography, I would strongly recommend for general use a rectilinear lens of eight to nine inches focus and a camera taking a 5 x 7 plate. The pictures that may be taken by the method here described are fully equal to those taken by daylight in a regular gallery, but in each case the excellence of the picture will depend in great measure on the quality of the lens and the skill displayed in the development of the plate. With the exception of development, all other manipulations may be learned in ten minutes from any practical photographer. 10 West 35TH Street.
1.) Read at the meeting of the New York Dermatological Society, Dec. 30,1887.
2.) Since the above was written, an explosion, causing death, has resulted from one of these
chloral of potash mixtures.