This was between the time of the wet plate process and the modern dry plate, when they used collodial bromide emulsion. It was a kind of a compromise between the wet plate and the dry plate. In 1871, Dr. R. L. Maddox, of Bath, England, had the idea that he would use gelatine, instead of albumen or collodion, as a vehicle to hold these silver salts upon the glass surface, and he found, among other things, something that surprised him—that when he put the silver salts in to contact with this gelatine they became wonderfully more sensitive than ever before.
The idea is this: That you make a gelatine mixture of a certain strength—the proportions required a certain amount of soft gelatine and a certain amount of hard gelatine. Into that gelatine you pour, with constant stirring; you pour a mixture at the same time—some particular bromide, generally bromide of potassium and nitrate of silver—in a very thin stream and keep it thoroughly stirred up. If you go too fast, you will not get the right result; but the result is, when you get through and do it right, you get a beautiful milky fluid, and that fluid contains bromide of silver in a wonderful state of suspension—very thin—and it remains suspended in this fluid. Now let that set—this cream or “emulsion,” as they call it—and you have as a result iodide of silver and iodide of potassium. You let the emulsion set and it produces a jelly, that jelly is then cut up into shreds, rubbed through a sieve or something of that kind to make it thoroughly divided, and washed thoroughly with water. Having done that it can be melted, and if you melt it and heat it to a certain temperature, there does not seem to be any limit to the sensitiveness of the material. If you use it cold it requires a second or two to produce a picture. If you cook it, however, you will find that it will become more and more sensitive to light, until it is actually possible to take a picture of a projectile traveling four hundred metres per second. I have such a picture. The only trouble is that some of the plates made are so sensitive to light that we cannot get a light non-active enough to develop them. Having these bromide plates then in the camera—this sensitive material coated on these glass plates in the camera—you have got to be very careful that the light does not get to them. The consequence is that the plate holders are made with extreme care.
The result of this gelatine-bromide of silver process is this: that we can have plates in packages. We can put these emulsion plates and carry them off where we please, and, what is still more important, we can put the emulsion upon very thin material, and I have here (exhibiting them) thin sheets of celluloid upon which this emulsion has been spread and pictures taken. That is not all, either; they can make it still thinner (producing small camera) they can put it on a roll and in this camera is one of those rolls, and in that box I can take a hundred pictures without reloading the instrument. The way it is done, I, when I want to produce a new surface, simply wind the old one off with this winding machine. There is an opening at the front of the camera. Press just below this, so, and you have the picture. Now just wind the film off and you are ready for the next picture. Now pull it again, and this is so easy that some manufacturers say: “You simply push the button and we do the rest for you.” That is nonsense, they don’t do the “rest” for you. A friend of mine took one of these to Europe, and with it a dozen rolls of film, all of which he used. When he returned he sent them to the manufacturers and I think he got about twelve pictures back. Not every time you press the button is a good picture produced. You have to know a little bit about the science and use a little judgment.
Such is the state of photography to-day that this material can be spread upon any kind of transparent surface. In the case of plate, they are put in holders like this, generally only two on each side, and slipped into this frame in a dark room, in which no light can be used except one emitted through a deep red chimney. (The professor here exhibited such a chimney.) Then, the material that is used for developing these pictures is somewhat different from the old method. We use organic compounds, alkaline solutions, and organic matters capable of taking up oxygen. These organic materials, in conjunction with some alkali, are capable of taking up oxygen. They produce a disoxygenizing action. After dipping, that gives you the negative.
The prints are made in a variety of ways. The facility with which these apparati can be used has led to an enormous variety. You can have an apparatus something like that, or something like this, which is smaller.
In the United States there are to-day probably about ten thousand professional photographers and thirty or forty thousand amateurs, who usually do nothing but spoil plates. To give you an idea of some of the work done, not altogether by professionals, I have picked out from the number of pictures I have a few samples of the work. Here is a picture of a cattle ranch in Colorado. I have one a little larger of a horse race, but this is about as large as they can be made. That will give you an idea of the instantaneous effect. The distance between the foot and the top of the mountains is about twelve miles, so that you can get an idea of the capacity of the camera, of the sensitiveness of these compounds. Here is a Mexican picture which shows the great beauties of the Mexican flora—the cacti. Here is a study “King Lear” made by Buffler, the photographer. That is about as large as you can get. It is a pretty large plate to handle. Then there is another study “The Five O’clock Tea” some ladies at tea, by the same man as “King 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 if 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 interesting—“In Camp.” The shadows in that picture are on the white paper underneath.
Here are a couple of pictures of silver, two Bavarian pictures. This one, of a little girl, is by Einlander of Cologne, instantaneously taken without a head-rest, which is a very difficult piece of work. This is the same idea, instantaneously taken. Here are two pictures very interesting, which were in the exhibition 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 chlorides 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.