The Emission and Transmission of Rontgen Rays . the goldleaf of a Wilson tilted electroscope E (fig. 2) was shielded by earthed tubes. The outsideof the ionisation chamber was raised by means of a battery of small accumulators, withthe negative pole earthed, to a potential (200 volts) sufficient to give a saturationcurrent for any type of Rontgen ray. A lead enclosure shielded the electroscope, andanother surrounded the discharge tube. Measurements. The very great range in sensitiveness that a tilted electroscope provides was a greatconvenience in the present work, owing to the large variation
The Emission and Transmission of Rontgen Rays . the goldleaf of a Wilson tilted electroscope E (fig. 2) was shielded by earthed tubes. The outsideof the ionisation chamber was raised by means of a battery of small accumulators, withthe negative pole earthed, to a potential (200 volts) sufficient to give a saturationcurrent for any type of Rontgen ray. A lead enclosure shielded the electroscope, andanother surrounded the discharge tube. Measurements. The very great range in sensitiveness that a tilted electroscope provides was a greatconvenience in the present work, owing to the large variations in intensity of the raysdealt with. A potential divider, P, giving a control of a fraction of a volt, was usedto furnish a fine adjustment oil the potential of the charged plate of the electroscope,which ordinarily was raised to something in the neighbourhood of 200 volts* 128 MR. G. W. C. KAYE ON THE A calcium-chloride solution key, K? which was operated from a distance, made orbroke the earth connection to the gold-leaf system. ?TO EARTH. A ft- MO EARTH Fig. 2. The gold leaf of the electroscope was viewed through a low-power microscope, havinga scale in the eye-piece. Its time of travel over a definite range was taken with astop-watch, and was usually from 20 to 60 seconds. When things were working well,ail accuracy of 1 per cent, could be obtained. In a comparison of the radiations froma pair of metals, they were used alternately until the readings were concordant. Before the mercury-break was employed, a standard bulb with a platinum anticathodewas joined in series with the experimental one. It was provided with an ionisationchamber and electroscope, and thus served as a check on the constancy of the currentpassing through the two bulbs. But if the mercury-break was working well, the useof this standard bulb was not found to be necessary. Results. The results for the aluminium, copper, and platinum screens will be discussed fully,and may be regarded as typical of the rest
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectproceed, bookyear1909
