. The evolution of forces . bo 5 ^ •2 ° PHOSPHORESCENCE PRODUCED BY LIGHT 229 of the luminous rays falling on the plate. In study-ing the action of light on phosphorescent bodies,these latter ought to be spread on glass or card-board screens. The process of making phosphorescentscreens, which I finally adopted after trying several,is the following:—The sulphide is ground in an agatemortar and passed through a sieve of the very finestsilk. It is then thoroughly mixed in the same mortarwith a varnish known to colour merchants as bronzingvarnish; the proportion of the powder added to thevarnish m
. The evolution of forces . bo 5 ^ •2 ° PHOSPHORESCENCE PRODUCED BY LIGHT 229 of the luminous rays falling on the plate. In study-ing the action of light on phosphorescent bodies,these latter ought to be spread on glass or card-board screens. The process of making phosphorescentscreens, which I finally adopted after trying several,is the following:—The sulphide is ground in an agatemortar and passed through a sieve of the very finestsilk. It is then thoroughly mixed in the same mortarwith a varnish known to colour merchants as bronzingvarnish; the proportion of the powder added to thevarnish may vary according to the quality of thelatter, but must not be less than 30 per cent. Whenthe mixture is perfectly homogeneous, it is poured,without beinof allowed to settle and in the samemanner as collodion, on to a piece of cardboard laidflat. Care must be previously taken to gum on theedges of the card a small mount half a millimetrethick, and two or three millimetres wide. If the mixture is poured on to a strip of
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Keywords: ., bookcentury1900, bookdecade1900, bookid, booksubjectradioactivity
