Experimental Science: Elementary, Practical and Experimental Physics, Volume 1 (Google eBook)

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Munn, 1902 - Physics
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Page 373 - ... 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 I have thus confirmed many observations originally made by eye observation with the fluorescent screen.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...
Page 372 - If the hand be held before the fluorescent screen, the shadow shows the bones darkly, with only faint outlines of the surrounding tissues. Water and several other fluids are very transparent. Hydrogen is not markedly more permeable than air. Plates of copper, silver, lead, gold, and platinum also allow the rays to pass, but only when the metal is thin. Platinum .2 mm.
Page 375 - ... 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. It is, however, well to detail an observation which at first sight seemed to lead to an opposite conclusion. I exposed a plate ,...
Page 372 - 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 aluminium foil were so arranged as to produce the same weakening of the effect.
Page 374 - X rays are capable of transformation. It is also certain that all the X rays falling on a body do not leave it as such. The retina of the eye is quite insensitive to these rays; the eye placed close to the apparatus sees nothing.
Page 371 - 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 neighborhood of the tube, whether the painted side or the other be turned towards the tube.
Page 375 - Xrays; 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.
Page 373 - 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.
Page 376 - 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...
Page 372 - If a square rod of wood 20 mm. in the side be painted on one face with white lead, it casts little shadow when it is so turned that the painted face is parallel to the X-rays, 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...

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