讀者評論 - 撰寫評論
其他版本 - 查看全部
acid albumen aluminium amateur photographer ammonia apparatus artistic bath bichromate block blue bromide of silver Bulletin Camera Club carbon carbon printing cathode rays chloride chrome alum Class coated collodion collotype color Company copper Crookes tube degrees desired dissolved dried dry plates effect emulsion enamel Engraving etching exhibition experiments exposed exposure film fluorescence formula Geissler tube gelatine give glass grains H. T. ANTHONY half-tone hand hypo illustrations inches lantern lens light lines metal method minutes negative nitrate nitric acid obtained ordinary orthochromatic orthochromatic plates ounces paper photo-engraving picture plate-holder potash potassium potassium bromide powder practical printing produced Prof quantity removed Rontgen salt screen sensitive shadows shellac side silver bromide silver nitrate slides soda solution stereoscopic sulphite surface thick thin tion tone transfer transparent W. K. Burton washed X rays yellow zinc
第 72 頁 - X-rays; in effect, both an ebonite and a glass lens of large size prove to be without action. The shadow photograph of a round rod is darker in the middle than at the edge; the image of a cylinder filled with a body more transparent than its walls exhibits the middle brighter than the edge. 8. The preceding experiments, and others which I pass over, point to the rays being incapable of regular reflection.
第 72 頁 - ... this connection is the fact that photographic dry plates are sensitive to the x-rays. It is thus possible to exhibit the phenomena so as to exclude the danger of error. I have thus confirmed many observations originally made by eye observation with the fluorescent screen. Here the power of the x-rays to pass through wood or cardboard becomes useful. The photographic plate can be exposed to the action without removal of the shutter of the dark slide or other protecting case, so that the experiment...
第 72 頁 - Investigations with water and carbon bisulphide in mica prisms of 30 degrees showed no deviation either on the photographic or the fluorescent plate. For comparison, light rays were allowed to fall on the prism as the apparatus was set up for the experiment. They were deviated 10 mm. and 20 mm. respectively in the case of the two prisms. With prisms of ebonite and aluminum I have obtained images on the photographic plate which point to a possible deviation.
第 71 頁 - ... but a strong shadow if the rays have to pass through the painted side. The salts of the metals, either solid or in solution, behave generally as the metals themselves. (3) The preceding experiments lead to the conclusion that the density of the bodies is the property whose variation mainly affects their permeability. At least no other property seems so marked in this connection. But that the density alone does not determine the transparency is shown by an experiment wherein plates of similar...
第 71 頁 - No. 4). 4. Increasing thickness increases the hindrance offered to the rays by all bodies. A picture has been impressed on a photographic plate of a number of superposed layers of tinfoil, like steps, presenting thus a regularly increasing thickness. This is to be submitted to photometric processes when a suitable instrument is available. 5. Pieces of platinum, lead, zinc, and aluminum loil were so arranged as to produce the same weakening of the effect.
第 71 頁 - From these values it is clear that in no case can we obtain the transparency of a body from the product of its density and thickness. The transparency increases much more rapidly than the product decreases. (6) The fluorescence of barium platinocyanide is not the only noticeable action of the x-rays. It is to be observed that other bodies exhibit fluorescence, eg calcium sulphide, uranium glass, Iceland spar, rock-salt, &c.
第 70 頁 - ON A NEW KIND OF RAYS} (i) A DISCHARGE from a large induction coil is passed •**• through a Hittorfs vacuum tube, or through a well-exhausted Crookes' or Lenard's tube. The tube is surrounded by a fairly close-fitting shield of black paper ; it is then possible to see, in a completely darkened room, that paper covered on one side with barium platinocyanide lights up with brilliant fluorescence when brought into the neighbourhood of the tube, whether the painted side or the other be turned towards...
第 75 頁 - X rays even in very strong magnetic fields. The deviation of cathode rays by the magnet is one of their peculiar characteristics ; it has been observed by Hertz and Lenard that several kinds of cathode rays exist, which differ by their power of exciting...
第 75 頁 - X rays, so that, for example, Iceland spar might exhibit different phenomena according to the relation of the surface of the plate to the axis of the crystal. Experiments with quartz and Iceland spar on this point lead to a negative result. (10) It is known that Lenard, in his investigations on cathode rays, has shown that they belong to the ether and can pass through all bodies. Concerning the X rays the same may be said.
第 71 頁 - X rays (as I will call the rays, for the sake of brevity) to pass, but greatly reduced the fluorescence. Glass plates of similar thickness behave similarly ; lead glass is, however, much more opaque than glass free from lead. Ebonite several centimeters thick is transparent. If the hand be held before the fluorescent screen, the shadow shows the bones darkly, with only faint outlines of the surrounding tissues.