and Laboratory Methods. 1947 



r NEWS AND NOTES. J 



Richard Leach Maddox.* — Richard Leach Maddox was born at Bath in 

 1816, and died at Southampton May 11, 1902. He was a physician and prac- 

 ticed in many cities of England and southern Europe, but devoted much time to 

 microscopy, photo-micrography and photography. 



It is to his experiments in photography that science is most indebted to him, 

 for he was the first to publish a formula by which an emulsion of gelatine and a 

 bromide were used in making dry plates. He gave three reasons for undertak- 

 ing these experiments : " Firstly, the cost of collodion, with the troublesome 

 manufacture of the cotton ; secondly, health more or less affected by its constant 

 use when working, as I was, in my camera, a dressing room, often at a very high 

 temperature in the summer months ; and thirdly, dissatisfaction with the dry 

 methods for the photo-micrographic work upon which I was much engaged." 



In his original experiments with gelatin, Dr. Maddox pursued the following 

 method : " Thirty grams of Nelson's gelatin were washed in cold water, then 

 left to swell for several hours, when all the water was poured off and the gelatin 

 set in a wide-mouthed bottle, with tHe addition of four drachms of pure water 

 and two small drops of aqua regia, and then placed in a basin of hot water for 

 solution. Eight grains of bromide of cadmium dissolved in half a drachm of 

 pure water were now added, and the solution stirred gently. Fifteen grains of 

 nitrate of silver were next dissolved in half a drachm of water in a test tube, and 

 the whole taken into the dark room, when the latter was added to the former 

 slowly, stirring the mixture the whole time. This gave a fine milky emulsion, 

 and was left for a little while to settle. A few plates of glass well cleaned were 

 next levelled on a metal plate put over a small lamp ; they were, when fully 

 warmed, coated with the emulsion spread to the edges by a glass rod, then 

 returned to their places and left to dry. When dry, the plates had a thin, opal- 

 escent appearance, and the deposit of bromide seemed to be very evenly spread 

 in the substance of the substratum. These plates were printed in succession 

 from different negatives, one of which had been taken years since on albumen 

 "with ox-gall and diluted phosphoric acid, sensitised in an acid nitrate bath, and 

 developed with pyrogallic acid, furnishing a beautiful warm brown tint. The 

 exposure varied from the first plate thirty seconds to a minute and a half, as the 

 light was very poor. No vestige of an outline appeared on removal from the 

 printing frame. The plates were dipped in water to wet the surface, and over 

 them was poured a plain solution of pyrogallic acid, four grains to the ounce of 

 water. Soon a faint but clear image was seen, which gradually intensified up to 

 a certain point, then browned all over ; hence the development of the others was 

 stopped at an early stage, the plate washed, and the development continued in 

 fresh pyro, with one drop of a ten-grain solution of nitrate of silver, then re- 



* British Journal of Photography, 49 : 2195. 



