. The Alumni journal. College of Pharmacy of the City of New York; Pharmacology. PUBLISHED BY THE ALUMNI ASSOCIATION OF THE COLLEGE OF PHARMACY OF THE CITY OF NEW YORK. Vol. II. New York, February, 1895. No. 2. "THE RISE AND PROGRESS OF ; By Prof. ARTHUR H. ELLIOTT, , F. C. S. LIBRA NEW Yi BOTANI GAROI '"THE topic of my lecture this evening * is one of my old hobbies, so that if I am a little prolix sometimes you must pardon me. It is something in which I have been more or less interested for the last twenty-five years, and, like most of our hobbies, we sometime
. The Alumni journal. College of Pharmacy of the City of New York; Pharmacology. PUBLISHED BY THE ALUMNI ASSOCIATION OF THE COLLEGE OF PHARMACY OF THE CITY OF NEW YORK. Vol. II. New York, February, 1895. No. 2. "THE RISE AND PROGRESS OF ; By Prof. ARTHUR H. ELLIOTT, , F. C. S. LIBRA NEW Yi BOTANI GAROI '"THE topic of my lecture this evening * is one of my old hobbies, so that if I am a little prolix sometimes you must pardon me. It is something in which I have been more or less interested for the last twenty-five years, and, like most of our hobbies, we sometimes drive them to death, to the discomfort of other people. The fundamental ideas upon which photography is based are very old— older than the Christian era, certainly. They depend upon two facts : First— that light, in passing through a small opening, produces an inverted image in a dark chamber. Imagine, for instance, that you are in a dark chamber, outside of which is an object ; that there is in the chamber a small hole a sixteenth or an eighth of in diameter, and that you have in this dark chamber a piece of paper. Upon that paper you will get a picture of the object opposite the hole. That was known a long time ago. The other fact is that certain salts of sil- ver, notably the chloride, iodide and bro- mide of silver, are sensitive to light and become blackened by light, was known to the Egyptians. The action of light upon colored bodies must have been known to the very earliest observers among men. The bronzing of the hu- man skin under the tropical sun must have been noted by every one ; and it is on record, in the most ancient annals of the human race, that men—the fair men from the North — when they went to the tropics, returned with tanned skins. Ptolemy, over two thousand years ago, noted that beeswax was bleached in sun- light, and the old Greeks noted that the gems which we call opal and amethyst lost their colors when exposed to sun- shine. These ar
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