4o 



THE ALUMNI JOURNAL, 



Lear." Here is another study, "A Game 

 of Sixty six." Those are all silver 

 prints, made with chloride of silver, 

 using glass negatives and producing the 

 positives by having the chloride of silver 

 in albumen. The best vehicle to-day for 

 making positive prints is albumen with 

 chloride of silver. 



It is found that it you take a mixture 

 of gelatine and bichromate of potassium, 

 and put into the mixture some pigment 

 and expose it under a negative where the 

 light acts, the gelatine is made insoluble 

 and holds the pigment, and where the 

 light does not act the gelatine is still 

 soluble and can be washed away. Here 

 is such a picture and it is very interest- 

 ing — " Iu Camp." The shadows in that 

 picture are on the white paper under- 

 neath. 



Here are a couple of pictures of silver, 

 two Bavarian pictures. This one, of a 

 little girl, is by Kinlander of Cologne, 

 instantaneously taken without a head- 

 rest, which is a very difficult piece of 

 work. This is the same idea, instan- 

 taneously taken. Here are two pictures 

 very interesting, which were in the ex- 

 hibition at Chicago. They are pictures 

 in platinum, showing that we are not 

 confined to simply silver salts. We have 

 here in this last picture one of the chlo- 

 rides of platinum, the platine chloride. 

 It cannot be spoiled in any way. The 

 picture is good as long as the paper is 

 good. 



Here is an example of a yacht picture. 

 It is the English yacht Iris. It is a fine 

 picture. The yacht is travelling very fast 

 Here is a picture on the East River, 

 made by Dr. Habershaw, showing the 

 work of amateurs in this line. 



I could tell you a good deal more 

 about this subject, but there is only one 

 other thing I would now like to mention. 

 Some of you, I suppose, have heard a 

 great deal about taking photographs in 

 colors. We are very near it. They 

 have produced in France, Germany and 

 England pictures of the spectrum in the 

 silver salts ; that is to say, with the col- 

 ors of the spectrum. They are very 

 weak and have to be looked at in a cer- 

 tain light. They are the result of inter- 

 ference of the thin films. We are doing 

 something more important. We are learn- 



ing to make the whole spectrum. For ex- 

 ample, we can to-day get just as good an 

 impression upon silver salts with a red 

 light as Scheele did with a violete light 

 in 1774. That leads to what is called 

 ortho-chromatic photography, that is 

 photography that will give us every 

 color in the spectrum. It has been 

 found possible to make pictures in certain 

 colors. A long time ago, the spectrum 

 was separated into three colors, red, yel- 

 low and blue of certain kinds. 



Now, if you take a picture in a red 

 light of a certain character, and another 

 of the same subject in a yeilow light of a 

 certain character, and another in a blue 

 light of a certain character, you have 

 three negatives. You can make three 

 negatives, one of the red light, one of 

 the yellow light anH one of the blue light. 

 Now, by taking pigments and printing in 

 a press like a lithographic press, you can 

 make a red positive from the red nega- 

 tive, and a blue positive from the blue 

 negative and a yellow positive from the 

 yellow negative, and in that way you may 

 get three impressions, which is the result 

 in the same colors. You must not stop 

 there, however. There is a certain amount 

 of shadow, and the result of it is that they 

 have to what they call "over-lay," taking 

 the three colors separately and superim- 

 posing them in printing. Remember, the 

 red parts of the picture are taken with 

 the red light. That is, suppose you put 

 a red piece of glass in front of your 

 camera, then only the red parts of the 

 picture pass through to the sensitive 

 plate. Then repeat the operation with 

 the blue glass and the yellow glass, and 

 the result will be as above. 



Now I hope I have not bored you by 

 any profuse details. I did not intend to. 

 I only tried to interest you in one of the 

 most important inventions of the Nine- 

 teenth Century. The steam engine, the 

 telegraph, the telephone and the photo- 

 graph are four of the grand inventions 

 which the century has produced, and I 

 think every intelligent person should 

 learn something about them. I am afraid 

 that I have had too little time to do the 

 subject justice. You can understand 

 how much more there is behind this 

 superficial view. I only have to thank 

 you for your very kind attention. 



