MAGIC WOOD, a wood used in cups which were sent to Spain in the 16th century as presents to princes, and were highly valued first as curiosities and later as a means of health. The "magic° consisted in the fact that water put into the cup speedily turned a rich blue. Although it has been a subject of in quiry ever since it is not until lately that the wood has been identified botanically, and the cause of its effect on water is still unknown. The identification was made by William E. Saf ford, of the United States Department of Agri culture, who described the result of his investi gation in The American Museum Journal (New York, Vol. XVIII, p. 48, 1918) with a colored illustration. He has discovered that two sepa rate kinds of wood are involved in the history of this matter. The description of the early writers mostly refer to a shrub of Mexico called sweet-wood (Eysenhardtia polystacha); but the cups were made of wood of the gigan tic narra tree (Pterocarpus indicus) of the Philippines. Although very different botani cally, both produce effects on water virtually indistinguishable; and as in early times most of the communication between Spain and the Philippines was by way of Mexico, the double confusion as to origin easily arose. When water was poured into the narra cups, or chips of the Mexican sweet-wood were infused in a glass, the water became fluorescent in beautiful colors. In the early accounts of the cups (Pterocar pus) it was said that the water at once turned blue, which deepened if left to stand for some time. When this water was poured into a
flask and held to the light it appeared perfectly clear, gut if you move this glass phial toward a more shady place the liquid will assume a most delightful greenness, and if to a still more shady place, a reddish color. . . . In the dark, however, or in an opaque vase, it will once more assume its blue color.) As was cus tomary in those days this changeably tinted water was regarded as having medicinal value, especially in any disorder of the kidneys, and was carried to Europe in great quantities and thus used under the name lignum nephriticum. Mr. Safford got similar colors from the Mexi can shrub. A few small chips in ordinary tap water tinged it a golden yellow, which soon deepened to orange. When the glass was held against a dark background the liquid glowed with a beautiful peacock fluorescence very much like that seen in quinine. Placed partly in a sunbeam, half of the liquid appeared yellow and the other half blue; rand when the sun light was focussed upon it by the lens of a com mon reading-glass the vial seemed to be filled with radiant gold penetrated by a shaft of pure cobalt?) The most ingenious investigation has failed thus far to reveal the cause of this flu orescence.