722 



PHOTOGRAPHY, RECENT PROGRESS IN. 



indoors or out, where the subject presents vio- 

 lent contrasts of light and shade. 



The successful use of " orthochromatic " plates 

 has greatly increased the interest in the study of 

 approximated color values in the photographic 

 image. The orthochromatic plate is designed to 

 overcome wholly or in part the difficulty brought 

 about by the varying degrees of actinism in col- 

 ors that the camera is called upon to interpret. 

 That blue, which is intensely actinic, and yellow 

 and red, which are relatively non-actinic, should 

 be rendered by the negative in exaggerated con-" 

 trast has been a serious drawback in the photo- 

 graphic image. A plate having an increased 

 sensitiveness to yellow and red and a decreased 

 sensitiveness to blue makes it possible to trans- 

 late nature more fairly. In the copying of paint- 

 ings the ordinary plate gives the blue sky as 

 white, and objects in the rich red and orange 

 tones lose most of their modeling. A plate giv- 

 ing better gradations of color is proving of great 

 usefulness, especially as the photographic nega- 

 tive is the basis of so large a number of repro- 

 ductive processes. For portraiture these plates 

 have been serviceable by reason of the fact that 

 they do not exaggerate freckles or other facial 

 blemishes, and give better tone values to brown 

 and reddish hair as well as to the eyes. Schu- 

 mann gives the following formula for preparing 

 orthochromatic dry plates with a cyanine bath : 

 Soak the plate in 200 c. c. of water and 2 to 4 

 c. c. of stronger ammonia for two or three min- 

 utes ; then immerse in distilled water, 200 c. c. ; 

 alcohol, 10 c. c. ; stronger ammonia (0 - 9), 4 c. c. 

 alcohol solution of cyanine (1 in 500), 10 c. c. 



Ives's chlorophyll and eosin process for or- 

 thochromatic dry plates is this : Use any good 

 bromide collodion emulsion that contains no free 

 nitrate of silver. Plow plate as usual, and as 

 soon as the emulsion film sets flow several times 

 with strong alcoholic solution of chlorophyll 

 from blue myrtle or plantain leaves ; then im- 

 merse in water strongly tinted with blue shade 

 eosin, and keep in motion until smooth. This 

 sensitizes for all colors. A. very light yellow 

 screen .is sufficient to secure correct rendering of 

 color values. 



Photography in Color. No movements or 

 speculations in photography have excited greater 

 interest than those related to the search for the 

 photograph in color. At frequent intervals dur- 

 ing a long period the announcement has been 

 made that this philosopher's stone of the photo- 

 graphic science was at last found. The repeated 

 disappointments have evoked a natural skepti- 

 cism in many quarters, but each new announce- 

 ment excites fresh hope that the dream is to be 

 realized. All the early workers sought to catch 

 the colors of nature. Sir John Herschel claimed 

 to have seized a faint colored image of the solar 

 spectrum. Becquerel, who introduced chloro- 

 phyll in 1874, produced on metal plates faint 

 images of certain colors. But even these soon 

 faded. Niepce de St. Victor's colored prints 

 quickly faded in daylight. In general the experi- 

 ments, early and late, have moved upon two 

 lines, one looking to a single positive image in 

 color, the other seeking to produce a positive im- 

 age in color by the agency of one or more nega- 

 tives. Collen sought to superpose red, yellow, 

 and blue prints taken from negatives made by 



yellow and blue, red and blue, and yellow and 

 red light. Duhauron, who asked for a patent as 

 early as 1868, sought to improve on Collen's plan 

 by the use of color screens to filter the color 

 rays. But the inventor in despair admitted that 

 " the production of good results will ... in- 

 volve the manufacture of compounds that have 

 not yet been created." Poiree suggested a dif- 

 ferent negative for each spectrum color, and Dr. 

 Vogel, in 1885, a modification that was extreme- 

 ly complicated. Dr. Stolze, denying the theory 

 that all colors are based on three primary or 

 principal colors, argued that if three suitable 

 selective color screens were used in connection 

 with color sensitive plates three negatives of the 

 spectrum might be obtained, from which prints 

 in cyan blue, carmine, and yellow, if superposed, 

 would reproduce the color effect of the spec- 

 trum. In 1888 Frederick E. Ives, of Philadel- 

 phia, taking up Stolze's comparatively indefinite 

 theory, demonstrated a procedure based upon 

 the assumption that, although there are more 

 than three or five or seven primary spectrum 

 colors, all of them can be counterfeited to the 

 eye by three type colors and mixtures of these 

 three type colors. Mr. Ives proved his process 

 by photographing the spectrum itself, employing 

 compound color screens carefully adjusted to 

 secure definite intensity curves in the spectrum 

 negatives, so that they would make color prints 

 that counterfeited the color effect of the spec- 

 trum when superposed. Shortly afterward Mr. 

 Ives set forth a new principle, that of making 

 sets of negatives by the action of light rays in 

 proportion as they excite primary-color sensa- 

 tions, and images or prints from such negatives 

 with colors that represent primary-color sensa- 

 tions. Mr. Ives's proposition included the state- 

 ment that while the spectrum is not made up of 

 three kinds of color rays and mixtures of these, 

 the eye is only capable of three primary-color 

 sensations. Ives claimed to produce the colors 

 of nature in permanent prints from three 

 negatives, or by composite heliochromy. By the 

 use of a combination lantern the colors could be 

 associated in a screen picture of remarkable 

 fidelity to nature. In a statement to the Frank- 

 lin Institute in June, 1891, Mr. Ives showed that 

 by an improvement on his heliochromatic cam- 

 era the three negatives could be made from one 

 point of view by simultaneous exposure and on 

 a single sensitive plate. The color prints were 

 made " by a single exposure in transparent gela- 

 tin, and separated only when ready to dip into 

 the dye solutions representing the respective col- 

 or sensations." The recent studies of Carey Lea, 

 of Philadelphia, have been regarded by many as 

 indicating a solution of the problem. Mr. Lea 

 has sought to apply the protochlorides of silver 

 in the form of an emulsion, and the products of 

 his experiments have excited much admiration. 

 In 1890 Franz Verescz exhibited at Vienna cer- 

 tain glass diapositives and paper prints. The 

 pictures on glass were described as showing " a 

 beautiful ruby-red ground color, with a picture 

 in bright pigments ranging from a deep hue of 

 red to light orange, and from violet to blue. 

 The same colors prevail on the paper positive." 

 But Verescz is said to have been unable to pro- 

 duce green. The pictures " bore the test of light 

 less intense than the direct rays of the sun." 



