ZINC SULPHIDE SCREENS. CALCIUM SULPHIDE—Phosphorescent. ZINC SULPHIDE—Phosphorescent. PITCHBLENDE—Specimens. _Write for particulars to_ JOHN J. GRIFFIN & SONS, Ltd., 20, 22, 24, 26, SARDINIA STREET, LONDON, W.C. ------------------------------------------------------------------------ RADIUM APPLICATORS Its employment in Therapeutics and for scientific research. (MacLeod) Surface, each =7s. 6d.= Throat, =£1 1s.= =BARIUM PLATINOCYANIDE SCREENS=, per sq. inch, =9d.= =CALCIUM SULPHIDE=, luminous, per lb., =8/-= =KUNZITE=, per Gm., =1/-= =POLONIUM, ON BISMUTH & COPPER DISCS=, each =25/-= =PITCHBLENDE=, specimens, each, per oz., =2/6.= =URANIUM NITRATE=, oz., =1/-.= =THORIUM HYDROXIDE=, oz., =4/-=; lb., =48/-.= =THORIUM HYDROXIDE PADS=, each =10/6.= =WILLEMITE=, Natural Specimens, =2/-= each. =WILLEMITE=, Artificial Specimens, =1/-= each. =ZINC SULPHIDE=, Active, Gm. =1/6.= =ZINC SULPHIDE SCREENS=, 10 × 10 centimetres, each =7/6.= [Illustration] =Special Quotations for Quantity.= =CHEMICALS AND APPARATUS= =for Scientific Research.= (_Write for Price List._) SPINTHARISCOPES _showing the Scintillations of Radium_, =21/-= [Illustration] =W. MARTINDALE=, Manufacturing Chemist, =10 NEW CAVENDISH STREET, W.= _Telegraphic Address: “Martindale, Chemist, London._” _Telephone: 1797 Paddington._ * * * * * RADIUM ON SALE AND LET ON HIRE.—Write for Terms. =The following can be had by return of post.= =Pitchblende=, direct from Joachimsthal, very radio-active, from =1/-= to =30/-= per piece. =Itacolomite=, or flexible sandstone, =10/-= to =25/-= per piece (very rare). =Kunzite, 1/-= per gramme. Selected, clear, =2/-= =Sparteite= (see NATURE, 31 3/04, fol. 523), =2/-= and upwards. =Chlorophane, 2/-= and upwards. =Barium Platino Cyanide in large Crystals= in course of manufacture. (ORDERS BOOKED). =Zinc Sulphide.= Phosphorescing a beautiful Green, =2/6= per tube. =Zinc Sulphide.= Phosphorescing a beautiful Yellow, =2/6= per tube. =Calcium Sulphide= Phosphorescing a beautiful Violet, =1/-= per tube. =Radio-active Residue= from which Radium is made; very scarce, =2/-= tube. =Polonium Sulphide=, in tubes of one gramme, =21/-= =Polonium= on Bismuth Rod or Disc, =25/-= =Polonium= on Copper Rod or Disc, =25/-= =Radio-active Screens= (Willemite), =6d.= per sq. inch. Plat. Bar. Cyan Screen., =9d.= sq. inch =Radio-active Screens= (Zinc Sulph.), 10 × 10 cm. =7/6.=