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is not suitable for toilet-ware, but another new material called "two-ply Britannia " is supplied for this purpose. Alumintin is sheet aluminum faced on both sides with pure block tin. It can be soldered and electro-plated without difficulty. Its specific gravity is 3.34. Such a light material that can be worked like copper will be much appreciated. It is supplied in sheets of the
π SIMILAR VOLUMES
## March, I917.] CURRENT TOPICS. 369 hole about a quarter of an inch in diameter, we can see the subject through it from any part of the plate area. In this way we practically turn the camera into a finder of the frame type, and this is all tl~at is necessary, actual focussing being neither requir
## I2I since the contraction induced by formalin separates the gelatin from the glass. Much more quinone and sodium-quinonesulphonate can be used than formalin without decreasing the fluidity of the resulting gelatin solutions. Uranium Ore in Mexico. (L'Ind. Chimica, x,27o.)--Mr. W. Niven discov