. The Becquerel rays and the properties of radium . can be spread out flat. A new mantle must be used,which lias not been fired, for after that it becomes too brittleto be touched. Spread out the mantle on the film side of aphotographic plate, and lay another glass plate on the top, soas to keep it flat. Leave the whole in a light tight box in adrawer or cupboard for at least a week. After that time haselapsed, take the plate out and develop it. A very clear picture of the mantle will be obtained, showingthe network black on a light ground. A print from this will,of course, more clearly repres
. The Becquerel rays and the properties of radium . can be spread out flat. A new mantle must be used,which lias not been fired, for after that it becomes too brittleto be touched. Spread out the mantle on the film side of aphotographic plate, and lay another glass plate on the top, soas to keep it flat. Leave the whole in a light tight box in adrawer or cupboard for at least a week. After that time haselapsed, take the plate out and develop it. A very clear picture of the mantle will be obtained, showingthe network black on a light ground. A print from this will,of course, more clearly represent the appearance of the mantleitself, for the network will then be white on a dark ground. Experiment 3 Photographic action of Pitchblende Obtain from a mineral dealer a piece of pitchblende, select-ing for preference a piece which contains other minerals, suchas quartz, felspar, and pyrites, embedded in it. Have onesurface of the piece cut flat and polished. This can be doneby an amateur, but practically it will save time aud money to PLATE liioro(;RArii of a Incandesckni Gas Man-ii,k,TAKKN HV Mr. Ricjiakij Kkrr. THK MANTLE WAS ) VT AND ON A :. INK l-:xr(>sUKIC ) r-()K HIGllT JJAVS, IIIK IMnHIUM CONTAINED IN THF-: MAKKS IT KAOIO-ACIIVK, AND EKAHLKS IT TO ACT ON [HI-: ILATE. ri-ATIC IT.
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectradioac, bookyear1904
