While the sodium vapor investigation was in progress I was at work on several other problems, one having to do with the remarkable optical properties of a chemical with a terrifically long name, nitrosodimethylaniline, which was one of the substances we had been required to make in Professor Remsen’s course in organic chemistry ten years before. It had struck me at the time that the bright green flakes with a metallic luster looked interesting, and I had preserved the material in a bottle. In the course of my lectures at Madison I had come to the subject of anomalous dispersion, shown by substances having strong absorption. A prism made of such a substance produces a spectrum in which the colors are not arranged in the same order as they are in the rainbow or in a spectrum formed by a glass prism, the deviation being greatest, but in opposite directions, for the colors close to and on either side of the absorption band. This phenomenon had previously been demonstrated and studied by solutions of aniline dyes contained in a hollow prism of glass. It had occurred to me that if I could fuse the pure dye and press it between two pieces of plate glass inclined at a small angle to each other, a much greater effect would be produced. I tried it with some crystals of cyanine, the dye used for sensitizing photographic plates for infrared rays. They melted easily and made beautiful prisms, which gave the effect in a greatly enhanced degree. Trials then made with about fifty other dyes showed that all were useless; they decomposed and swelled up into a spongy black mass without fusing, and I have never been able to find anything else that answered the purpose. Even cyanine made by other chemical plants would not melt. My sample was what horticulturists would term a “sport”, I suppose. Ehrlich had 605 failures before the successful 606th. I had one success followed by fifty failures! In looking over my preparations made years before in Remsen’s course I ran across the nitrosodimethylaniline green flakes. These green flakes melted at low temperature and gave beautiful prisms, which transmitted the red, orange, yellow, and green rays in normal order but gave a spectrum fifteen times as long as the spectrum produced by a glass prism of equal angle. Moreover, in solution, the substance absorbed the violet rays powerfully but transmitted the ultraviolet, and by combining it with dense cobalt-blue glass I obtained something that had been searched for in vain — a ray filter that would be opaque to visible light but transparent to the ultraviolet. With this filter I made my first landscape and lunar photographs in ultraviolet light, and at the autumn meeting of the National Academy in Baltimore in 1902 I gave an experimental demonstration of what could be done with what is now called black light.
The meeting was held in the lecture room of the physical laboratory, and after the exhibition of various photographs made exclusively by ultraviolet light, the room was completely darkened and the invisible rays from an arc lamp in a light-tight iron box were passed out through a single window made of the filter combination opaque to visible light. A white porcelain plate held in front of this window was invisible. The rays were brought to a focus by a large condensing lens on a pile of crystals of uranium nitrate, which immediately glowed with a brilliant yellow-green light, of sufficient intensity to read by. Newspaper accounts of the meeting record that this experiment “was received by a burst of applause, a reception rarely accorded at dignified Academy meetings”.
Wood never denied himself the chance to make grandstand demonstrations such as this, but he didn’t let them interfere with his laboratory research. During 1902 alone ten scientific papers of his appeared in the Philosophical Magazine; and a German physicist wrote to an American friend at this time, “Wood — he produces like a rabbit”.
In the summer of 1902 the Woods all went to San Francisco to visit Gertrude’s parents, who had sold the house in Ross Valley and reopened their house at 1312 Taylor Street. A new addition to the family was expected about the middle of July, and Gertrude insisted that this was the obvious time for Robert to visit the Hawaiian Islands, where he had always wanted to go because of his father’s early life there. Wood’s protests against the infamy of a husband deserting his wife at such a time were pronounced “rubbish” by Gertrude, who finally persuaded him to abandon her. She would be perfectly all right with her mother, nurse, and the doctor to take care of her. In those days you always had your babies at home. Maternity hospitals were an unknown luxury.
Wood says:
So presently I found myself on a steamer heading out through the Golden Gate. The Islands in those days were quite free from the commercialization which they have undergone in the past quarter of a century. You could see real hula dances, while now I’m told they have an expurgated edition sponsored by the Eastman Kodak Company held every day for the benefit of tourists, in front of the beach hotels. I had one or two friends who lived in Honolulu and in a few days a lot more friends, for I was invited to a mou-mou party over a week end. The mou-mou was a native negligee, a single garment, or rather a long burlap gunny sack with three holes at one end, two for the arms and one for the head. On arriving at the large country house set back from the beach, I was informed that we were to shed our clothes and put on mou-mous, with nothing underneath. In this garment, which came down to your knees, you played a game of tennis or sat around tables with iced drinks, and then all went down to the beach for a swim, and then back under the trees, where the gunny sacks dried out in a few minutes, then another drink and another swim, then dinner all in mou-mous around a long table, with champagne, then another swim by moonlight, “and so to bed”, all of the men in one big room and the women in another in a distant part of the house, and the “roll” called before the lights went out to make sure that all were “present or accounted for” and that no one was A.W.O.L.
The tame spiders were terrifying, and were in practically every country house or bungalow on the Islands. They are non- poisonous and are never molested, as they destroy millions of mosquitoes and other insect pests. The body is the size of a small hen’s egg, and the hairy legs spread out over an area the size of a large saucer. I had not been told about them when I visited Gertrude’s cousin on the island of Hilo, and on going to bed, just as I was stooping over to blow out the candle, I was startled by the sudden impact on the top of my head of something that felt like a frog, which bounced off onto the floor and scuttled under the bed. Looking over the ceiling I discovered three more of the creatures lurking in the dark corners. This was dive bombing on a larger scale than in the hotel in Omsk, and I shouted for my host, as I did not feel secure even under the mosquito net which covered the bed. He explained that they were pet spiders and lived on mosquitoes, and would eat out of your hand. Not out of mine, however!