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Correct color-tone photography with ordinary gelatine bromide plates
Aug., i886.]
Color-Tone tVkotograjO/ty.
12 3
c O R R E C T C O L O R - T O N E P H O T O G R A P H Y WITH O R D I NARY GELATINE BROMIDE PLATES. BY FRED. E. IVES.
[pafler read at meeting of FRANKLIN INSTITUTE, June I6t]l. l)resenled for ~SublicaNon June z8lh.]
Rev[sgd and
Chlorophyl-stained collodion bromide emulsion plates have been made four or five times more sensitive to spectrum red than to blue. It has been estimated that ordinary gelatine bromide plates are Ioo times more sensitive to blue than to red. T h e relative red sensitiveness of the chlorophyl-stained collodion plates is, therefore, probably 400 or 500 times greater than that of ordinary gelatine bromide plates. But the most rapid ordinary gelatine bromide plates are IOO times more sensitive to ordinary diffused daylight than the collodion emulsion plates, and it would, therefore, appear that the absolute red sensitiveness of the very rapid gelatine plate should be one-fifth as great as that of the v e r y slow chlorophyl plate. By recent experiment in photographing the lime-light spectrum, I have found this estimate to be very nearly correct for some makes of extra rapid gelatine bromide plates. What, then, is to prevent us from making correct color-tone photographs with very rapid ordinary gelatine dry plates ? T h e difficulties, although a p p a r e n t l y great, are not insurmountable, as I shall show; but the exposures are necessarily so long that the method is not available in many cases where the regular isochromatic processes can b e s u c c e s s f u l l y employed. I have calculated that, in order to secure correct color-tone without a color-screen, it would be necessary to have plates about ten times as sensitive to spectrum red as to blue; if this estimate is correct, the ordi nary rapid gelatine dry plate is relatively I,OOO times too sensitive. to blue, and in order to secure correct color-tone with such a plate it would be necessary to cut off T-f 9 9SlY 9 of the blue light, and green and yellow in due proportion. It is very easy to cut o f f a large portion, or all, of the blue light, but it required a great deal of patient experiment to p r o d u c e a color-screen that cut off just enough of the blue, and also of the green and yellow. I accom-
12 4
/yes.
[ J. F. '
plished this by a mixture of aniline color solutions in the plate. glass tank which I recommended for color-screen purpo;es, in 1879 . My first trial exposures were made 0n the lime-light spectrum. I c o m m e n c e d by adding aniline yellow to water in the tank, a little at a time, until so little blue light was transmitted that it produced very much less action than the red ; I then added aniline red until the green acted but little more than the blue, and aniline violet to slightly reduce the action of the yellow. A n exposure made in the camera, using this color-screen and a IV[.A. Seed plate, proved that m y Calculations were very nearly correct. I was only obliged to add a little more yellow and red to the color solution to secure correct color-tone in all the colors of a bright chromo, which I use as a test object. VVith exposures five times longer, I have secured results apparently equal to those obtained with m y chlorophyl-eosine plates and yellow screen. The result which I obtained cannot be even approximated by means of a screen of any sir~gle-color solution that has been tried, and I believe this to be the first specification of the production Of a color-screen actually capable of securing correct color-tone with ordinary plates. RELATION OF VAPOR TENSION TO INTERNAL FRICTION.--The phen o m e n o n of diffusion a n d the displacements of m i n u t e particles which are introduced into liquids show that liquids are formed of molecules, which are endowed with a perceptible m o v e m e n t of translation. Vaporization is, therefore, easily explained by a t t r i b u t i n g to some of the molecules a v i s viva sufficient to project t h e m b e y o n d the s p h e r e of activity of the superficial molecules. If we adopt this explanation, the v a p o r tension must be intimately c o n n e c t e d with the molecular velocities, which are themselves a function of the coefficient of internal friction. P. De H e e n h a s found an empirical formula, which represents very closely this theoretical ratio in ali' the bodies upon which h e has experimented. Designating b y ~ the v a p o r tension t a k e n at the absolute temperature T, a n d b y / t h e coefficient of friction at the s a m e temperature, we h a v e T / l o g . fi = const.--.BuL de l'Acad, de .Be/ft., No. 8,
~885. GEOLOGICAL THERNO-CHEMISTRY.--In order to determine the influence 0f t h e r m o - c h e m i s t r y in the production of metallic ores, Dieulafait assumes t h a t if we study each m e t a l a n d find which of its natural c o m b i n a t i o n s develops the greatest heat, t h a t combination will be found to represent the principal ore of the m e t a l u n d e r consideration. H e has tested his theory b y the four most frequent ores of m a n g a n e s e , a n d finds it to b e satisfactorily confirmed.
--Comfites Rendus, Oct. 5, zg82.
Color-Tone tVkotograjO/ty.
12 3
c O R R E C T C O L O R - T O N E P H O T O G R A P H Y WITH O R D I NARY GELATINE BROMIDE PLATES. BY FRED. E. IVES.
[pafler read at meeting of FRANKLIN INSTITUTE, June I6t]l. l)resenled for ~SublicaNon June z8lh.]
Rev[sgd and
Chlorophyl-stained collodion bromide emulsion plates have been made four or five times more sensitive to spectrum red than to blue. It has been estimated that ordinary gelatine bromide plates are Ioo times more sensitive to blue than to red. T h e relative red sensitiveness of the chlorophyl-stained collodion plates is, therefore, probably 400 or 500 times greater than that of ordinary gelatine bromide plates. But the most rapid ordinary gelatine bromide plates are IOO times more sensitive to ordinary diffused daylight than the collodion emulsion plates, and it would, therefore, appear that the absolute red sensitiveness of the very rapid gelatine plate should be one-fifth as great as that of the v e r y slow chlorophyl plate. By recent experiment in photographing the lime-light spectrum, I have found this estimate to be very nearly correct for some makes of extra rapid gelatine bromide plates. What, then, is to prevent us from making correct color-tone photographs with very rapid ordinary gelatine dry plates ? T h e difficulties, although a p p a r e n t l y great, are not insurmountable, as I shall show; but the exposures are necessarily so long that the method is not available in many cases where the regular isochromatic processes can b e s u c c e s s f u l l y employed. I have calculated that, in order to secure correct color-tone without a color-screen, it would be necessary to have plates about ten times as sensitive to spectrum red as to blue; if this estimate is correct, the ordi nary rapid gelatine dry plate is relatively I,OOO times too sensitive. to blue, and in order to secure correct color-tone with such a plate it would be necessary to cut off T-f 9 9SlY 9 of the blue light, and green and yellow in due proportion. It is very easy to cut o f f a large portion, or all, of the blue light, but it required a great deal of patient experiment to p r o d u c e a color-screen that cut off just enough of the blue, and also of the green and yellow. I accom-
12 4
/yes.
[ J. F. '
plished this by a mixture of aniline color solutions in the plate. glass tank which I recommended for color-screen purpo;es, in 1879 . My first trial exposures were made 0n the lime-light spectrum. I c o m m e n c e d by adding aniline yellow to water in the tank, a little at a time, until so little blue light was transmitted that it produced very much less action than the red ; I then added aniline red until the green acted but little more than the blue, and aniline violet to slightly reduce the action of the yellow. A n exposure made in the camera, using this color-screen and a IV[.A. Seed plate, proved that m y Calculations were very nearly correct. I was only obliged to add a little more yellow and red to the color solution to secure correct color-tone in all the colors of a bright chromo, which I use as a test object. VVith exposures five times longer, I have secured results apparently equal to those obtained with m y chlorophyl-eosine plates and yellow screen. The result which I obtained cannot be even approximated by means of a screen of any sir~gle-color solution that has been tried, and I believe this to be the first specification of the production Of a color-screen actually capable of securing correct color-tone with ordinary plates. RELATION OF VAPOR TENSION TO INTERNAL FRICTION.--The phen o m e n o n of diffusion a n d the displacements of m i n u t e particles which are introduced into liquids show that liquids are formed of molecules, which are endowed with a perceptible m o v e m e n t of translation. Vaporization is, therefore, easily explained by a t t r i b u t i n g to some of the molecules a v i s viva sufficient to project t h e m b e y o n d the s p h e r e of activity of the superficial molecules. If we adopt this explanation, the v a p o r tension must be intimately c o n n e c t e d with the molecular velocities, which are themselves a function of the coefficient of internal friction. P. De H e e n h a s found an empirical formula, which represents very closely this theoretical ratio in ali' the bodies upon which h e has experimented. Designating b y ~ the v a p o r tension t a k e n at the absolute temperature T, a n d b y / t h e coefficient of friction at the s a m e temperature, we h a v e T / l o g . fi = const.--.BuL de l'Acad, de .Be/ft., No. 8,
~885. GEOLOGICAL THERNO-CHEMISTRY.--In order to determine the influence 0f t h e r m o - c h e m i s t r y in the production of metallic ores, Dieulafait assumes t h a t if we study each m e t a l a n d find which of its natural c o m b i n a t i o n s develops the greatest heat, t h a t combination will be found to represent the principal ore of the m e t a l u n d e r consideration. H e has tested his theory b y the four most frequent ores of m a n g a n e s e , a n d finds it to b e satisfactorily confirmed.
--Comfites Rendus, Oct. 5, zg82.