phosphoresced by giving spots here and there, but they did not phosphoresce at a greater distance, and the light was probably not due to the X-rays. Edison attributed the result directly to the “electrical discharge.” The list is as follows: ammonium sulphur cyanide, calcic formate, and nitrate, ferric citrate, argentic nitrate, calcic and iron citrate, soda, lime, “zinc, cyanide” (perhaps this means cyanide of zinc), zinc hypermanganate, and zinc valeriate. The salts of the following metals did not fluoresce under the influence of the X-rays. Aluminum, antimony, arsenic, boron, beryllium, bismuth, barium, chromium, cobalt, copper, gold, iridium, magnesium, manganese, nickel, tin, and titanium. [Illustration: ROENTGEN RAYS AT THE UNIVERSITY OF MINNESOTA. 1. Watch and chain. 2. College badges in mahogany box. 3. Copper coin. 4. Weights in heavy velvet-lined mahogany box; blank space contains aluminum. 5. Coins in inner pocket of heavy seal purse. 6 and 7. Colored glass. 8. Key 9. Lead-pencil. _West. Elect._, Mar. ’96. ] Edison stated that the following substances were among those which fluoresced more or less under the action of the X-rays. Mercurous chloride, mercury diphenyl, cadmic iodide, calcic sulphide, potassic bromide, plumbic tetrametaphosphate, potassic iodide, plumbic bromide, plumbic sulphate, fluorite, powdered lead glass, pectolite, sodic cressotinate, ammonic salicylate, and salicylic acid. Compared with the above, the following fluoresced less. Powdered German glass, baric, calcic and sodic fluorides, sodic, mercuric, cadmic, argentic and plumbic chlorides, plumbic iodide, sodic bromide, cadmic and “cadmium, lithia bromide, mercury, cadmium sulphate,” uranic sulphate, phosphate, nitrate, and acetate, molybdic acid, dry potassic silicate, sodic bromide, wulfenite, orthoclase, andalucite, herdinite, pyromorphite, apatite, calcite, danburnite, calcic carbonate, strontic acetate, sodic tartrate, baric sulphobenzoic, calcic iodide, and natural and artificial ammonium benzoic. Not one of all the 1800 crystals and precipitates fluoresced through a thick cardboard under the influence of the arc light, 16 inch spark in air, a vacuum tube so highly exhausted that a 10 inch spark left it dark, nor the direct rays of the sun at noon time. As calcic tungstate was phosphorescent by friction, he theorized that the X-ray is a wave due to concussion. Flame sensitive to X-rays. Edison stated that his assistants submitted the sensitive flame and the phonographic listening tube to the action of the X-rays, and found that they were responsive thereto.