356 



NATURE 



[January 3, 19 18 



with spectroscopy. Among others may be mentioned 

 the Cavendish Laboratory at Cambridge and several of 

 the larger university laboratories which deal with the 

 physical chemistry of solutions. 



i3ut these university laboratories are rarely able to 



concentrate on to the group of problems which they 

 are studying specialists from such different branches of 

 science as are available for similar laboratories outside 

 the universities owing to the fact that it is very diffi- 

 cult to obtain interdepartmental co-operation in re- 

 search in a university. In a specialised laboratory, 

 on the dther hand, workers in all 

 branches of science may well col- 

 laborate in the investigation _ of /^ 

 problems representing different points 

 of view of one general subject. 



In addition to the examples of in- 

 dustrial and institutional laboratories 

 mentioned above I should like to 

 illustrate the structure of a conver- 

 gent laboratory, if I may be for- 

 given for doing so, by referring to 

 the organisation of the research 

 laboratory with which I am con- 

 nected — that of the Eastman Kodak 

 Co. 



The purpose of this laboratory is 

 lhe investigation of the scientific 

 foundations of photography and its 

 applications, everything relating to 

 photography in all its branches and 

 applications being of interest. The 

 branches of science which are of 

 chief importance in photographic 

 problems are those of optics in 

 physics and of the colloidal, physical, 

 and organic branches of . chemistry, 

 and the relations of these sciences to 

 photographic problems are shown in 

 graphic form in Fig. i. 



Optics deals on its geometrical 

 side with the materials used in 

 photography — cameras, lenses, shut- 

 ters, etc. — and on its physical side with such materials 

 as colour filters and illuminants, but especially with the 

 study of the relation of the photographic image to the 

 light by means of which it was produced — & study 

 which is known by the name of sensitometry. The 



NO. 2514, VOL. 100] 



manufacture of the sensitive material itself, which on 

 modern photographic plates, films, and paper is called 

 the emulsion, is a province of colloid and physical 

 chemistry, colloid chemistry dealing with the pre- 

 cipitation and nature of the sensitive silver salts formed 

 in their gelatine layer, while physical 

 chemistry informs us as to the nature 

 of the reactions which go on, both 

 in the formation of the sensitive sub- 

 stance and in its subsequent develop- 

 ment after exposure. 



The organic chemist prepares the 

 reducing agents required for de- 

 velopment and the dyes by which 

 colour sensitiveness is given to the 

 photographic materials and by which 

 the art of colour photography can be 

 carried on, and while the physicist 

 therefore deals with sensitometry 

 and the theory of exposure, the 

 chemist must deal at the same time 

 with the theory of development and 

 with the conditions relating to the 

 development of photographic images. 

 A laboratory, therefore, for the 

 study of photogra,phic problems 

 must be arranged with a number 

 of sections, such as are shown in 

 Fig. 2. In physics we require de- 

 partments dealing with sensitometry 

 and with illumination, reflection and 

 absorption, colorimetry, spectroscopy, and geometrical 

 optics. We need a department of colloid chemistry, one 

 of physical chemistry, one of organic chemistry, one of 

 photo-chemistry to deal with the action of light upon the 

 plate, and, finally, a number of photographic depart- 

 ments dealing with photographic chemistry, with por- 



traiture, colour photography, photo-engraving, motion- 

 picture work, and X-ray work, and all these depart- 

 ments are converged together first upon the theory, 

 and then upon the practice, of photography. 



Each research specialist in the laboratory is given 



