N Rays

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: On the Existence, in the Rays emitted by an Auer Burner, of Radiations which traverse metals, wood, etc. (May n, 19o3). A focus tube emits, as I have already proved (see p. 7), certain radiations susceptible of traversing metals, black paper, wood, etc. Amongst these, there are some for which the index of refraction of quartz is nearly 2. On the other hand, the index of quartz for the rays remaining from rock- salt, discovered by Professor Rubens, is 2'i8. This similarity of indices led me to think that the radiations observed in the emission of a focus tube would very likely be near neighbours of the rays discovered by Rubens, and that, consequently, they would be met with in the radiation emitted by an Auer burner, which is the source of such rays. I accordingly made the following experiment: an Auer burner is enclosed in a kind of lantern of sheet-iron, completely enclosed on all sides, with the exception of openings for the passage of air and combustiongases, which are so arranged that no light escapes; a rectangular orifice, 4 cms. wide and 6'5 cms. high, cut in the iron at the same height as the incandescent mantle, is closed by a sheet of aluminium i mm. thick. The chimney of the Auer burner is of sheet-iron, and a slit 2 mms. wide and 35 cms. high is cut in it, opposite the mantle, so that the emerging luminous pencil is directed on the aluminium sheet. Outside the lantern, and in front of this sheet, a double-convex quartz lens is placed, having 12 cms. focal length for yellow light, behind which is a spark-gap of the kind already described, giving very small sparks. The spark is produced by a small induction-coil, provided with a rotating make and break device, which works with perfect regularity. The distance / of the lens from the slit being 26'5 cms., one notes, ..