. Radio-active substances . the Rontgen raysthemselves. For the rest, the Becquerel rays might be classified ascathode rays propagated in the air. It is now known thatthese different analogies are all legitimate. Measurement of the Intensity of Radiation,The method employed consists in measuring the con-ductivity acquired by air under the action of radio-activebodies ; this method possesses the advantage of being rapidand of furnishingfigures which arecomparable. The ap-paratus employed byme for the purposeconsists essentially ofa plate condenser,A B (Fig. i). Theactive body, finelypowered, is
. Radio-active substances . the Rontgen raysthemselves. For the rest, the Becquerel rays might be classified ascathode rays propagated in the air. It is now known thatthese different analogies are all legitimate. Measurement of the Intensity of Radiation,The method employed consists in measuring the con-ductivity acquired by air under the action of radio-activebodies ; this method possesses the advantage of being rapidand of furnishingfigures which arecomparable. The ap-paratus employed byme for the purposeconsists essentially ofa plate condenser,A B (Fig. i). Theactive body, finelypowered, is spreadover the plate B,making the air be-tween the plates aconductor. In orderto measure the con-ductivity, the plate B is raised to a high potential by connecting it with one pole ofa battery of small accumulators, p, of which the other pole isconnected to earth. The plate A being maintained at thepotential of the earth by the connection c D, an electric currentis set up between the two plates. The potential of plate A is. Terre Fig, 8 MDME. curies THESIS: recorded by an electrometer, E. If the earth connection bebroken at c, the plate A becomes charged, and this chargecauses a deflection of the electrometer. The velocity ofthe deflection is proportional to the intensity of the current^and serves to measure the latter. But a preferable method of measurement is that of com-pensating the charge on plate A, so as to cause no deflec-tion of the electrometer. The charges in question areextremely weak ; they may be compensated by means of aquartz electric balance, Q, one sheath of which is connectedto plate A and the other to earth. The quartz lamina issubjected to a known tension, produced by placing weightsin a plate, ^ ; the tension is produced progressively, andhas the effect of generating progressively a known quantityof electricity during the time observed. The operation canbe so regulated that, at each instant, there is compensationbetween the quantity of electricity that tr
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradioac, bookyear1904
