. Radio-activity : an elementary treatise from the standpoint of the disintegration theory . uranium compound is put inside the 12 RADIO-ACTIVITY. vessel the leaves collapse within a few minutes. By making the instru-ment small the effect may be sufficiently rapid to be followed with theeye. The sensitiveness of the instrument, and the rate of collapse undergiven conditions, depends on its capacity, and this is regulated mainly bythe area of the leaves and their support which receive the charge. It may be pointed out that the electroscope would retainits charge indefinitely in vacuo, even in t
. Radio-activity : an elementary treatise from the standpoint of the disintegration theory . uranium compound is put inside the 12 RADIO-ACTIVITY. vessel the leaves collapse within a few minutes. By making the instru-ment small the effect may be sufficiently rapid to be followed with theeye. The sensitiveness of the instrument, and the rate of collapse undergiven conditions, depends on its capacity, and this is regulated mainly bythe area of the leaves and their support which receive the charge. It may be pointed out that the electroscope would retainits charge indefinitely in vacuo, even in the presence of uranium,or when acted upon by the X-rays—, the gas present playsa direct part in the transport of the electricity. The uraniumrays fail to excite fluorescence (for example, in barium platino-cyanide), but this almost certainly is because of their excessivelyJeeble character compared with the X-rays from an ordinary has also conclusively shown {Phil. Mag., 1899,v., 47, p. Ill, that the uranium rays are like X-rays, non-polarisable and Fig. 2.—Two Gold-leaf Electroscopes, Uncharged and Charged. It will be convenient at the present stage to anticipate theresults dealt v/ith in Chapter V. to the extent of givinga general account of the nature of the rays from uraniumand the other radio-active substances. These radiations havebeen analysed into three distinct types, which are differentiatedin the first instance by their power of penetrating three types have been termed respectively a, (3 andy-rays. The former are so feebly penetrating that theyare completely stopped by a single sheet of note paper orby a few centimetres of air. The yS-rays resemble ordinaryX-rays in penetrating power, and pass with ease through thinmetal foil, glass, &c., but would be nearly all stopped by RADIATION FHENOMENA. 13- a single coin. The y-rays are by far the most penetrating;kind of ray known, and pass through a pile of 12 coins with-ou
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradioac, bookyear1904
