. The Becquerel rays and the properties of radium . rties of uranium were discovered. We nowcome to the more sensational developments whichhave attracted so much attention of late. It is found that all the compounds of uranium emitBecquerel rays. They are all able to affect a photo-graphic plate which has been wrapped in black paper,and they can all dischai-ge a gold-leaf was a natural and obvious experiment to comparethe various compounds of uranium amongst them- c 34 THE BECQUEREL RAYS selves, in order to see which was the most experiment is not difficult. It is me
. The Becquerel rays and the properties of radium . rties of uranium were discovered. We nowcome to the more sensational developments whichhave attracted so much attention of late. It is found that all the compounds of uranium emitBecquerel rays. They are all able to affect a photo-graphic plate which has been wrapped in black paper,and they can all dischai-ge a gold-leaf was a natural and obvious experiment to comparethe various compounds of uranium amongst them- c 34 THE BECQUEREL RAYS selves, in order to see which was the most experiment is not difficult. It is merely neces-sary to place equal quantities of the various com-pounds successively on the plate of the gold-leafelectroscope, and to compare the times which theleaves take to collapse in each case. For this kind of work a special form of electroscopehas been devised, which is very convenient. The leafof the electroscope can be observed by means of amicroscope with a scale in the eye-piece, which isfocussed on it. Thus the rate at which the leaf goes. Fio, 11.—Electroscope designed by M. Curie for measurementsin radio-activity, Tlic instrument is enclosed in u brass case,ab c. Tlio front wall is of clear glass, tlie back one of obscuredglass, to provide a dillused light, A metal strip, d, hangs by aninsulating support, /, from the roof To this strip the gold leaf,e, is attached. A metal plate, h, is connected to d by a bratisrod, whiclt passes, witliout touching, through a hole in the second metal plate, g, is in metallic communication with thecase. On this the radio-active substance is spread, and causes uleak of electricity from the electrified i)late, h. The loaf thusgradually collapses. Tho rate of motion is read by means of amicroscope with scale in the eyepiece, focussed on the leaf. Forcharging the instrument, a knob (not shown) is provided, whichjirojects outside the case, carried by the rod, fc. This knob,also the plates h, g, are provided with metal covers to sc
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradioac, bookyear1904
