No. 63 180. 



Opto-electricity. Radioactivity. 



1027 



63 170. 1 : 3. 



63 180. 1 : 2. 



63.168. Spinthariscope, Figure 



The apparatus consists of a small brass tube on the back end of which is a small light screen 

 of zinc sulphide. In front of this screen a metal pointer is fitted which can be moved up and down 

 over the screen externally by the finger. At the lower side (i. e., the side opposite the luminous 

 screen) the indicator contains a little radium bromide. The radium-bromide permanently radiates 

 and the rays encounter the zinc sulphide screen, which lights up like a billowy, sparkling sea of light 

 when the screen is looked at through the magnifier placed on the front of the apparatus. 



The observation must be made in a perfectly dark room and the eye must rest for some time 

 (5 to 10 minutes) so as to become rid of other impressions and thus observe the phenomenon tho- 

 roughly well. 



63.169. Spinthariscope without Magnifier, for use under the microscope 



63.170. Case containing Collection of Radioactive Preparations, Figure 



The case contains: 1 spinthariscope (No. 1); 1 piece uranium pitch blende (No. 2); 1 piece wille- 

 mite (No. 3); 1 piece Kunzite (No. 4); 1 piece calc-spar (No. 5); 1 radium cell (No. 6); 1 cube 

 fluorspar, 13 mm side (No. 7); 1 barium platino-cyanide screen (No. 8) and one zinc-sulphide screen 

 (No. 9). 



The various apparatus and preparations contained in the collection are also sold singly at the 

 prices named below. 



The radium cell included in the collection is unfilled. If it is desired that it should be supplied 

 filled with radium-bromide the quantity and quality of the material desired should be specially in- 

 dicated. Prices quoted on application. 



63.171. Uranium Pitchblende for comparative experiments on radium, in pieces of 50 300 grammes. Per 100 g 



63,17'2. Uranium metal, quite pure, for use as unit of radiation Per gramme 



03,17.'!. Willemite, phosphorescent, in pieces of approx 30 g 



63.174. Kunzite, fluorescent, in pieces of 6 8 grammes 



63.175. Calc-spar, approx. 40x15x6 mm 



63.176. Fluorspar Cube, approx. 13 mm side 



63.177. Barium platinocyanide Screen, 65 x45 mm 



63.178. Zinc-sulphide Screen, 65x45 mm 



63.179. Mixture of Radium and Zinc-sulphide, in small sealed glass tube, phosphorescing in the dark . . . 



63.180. Apparatus for Studying Induced Radioactivity, Figure (cf. Besson, Le radium et 

 la radioactivite, Paris, 1904, Fig. 21) 



The apparatus consists of a small cylinder and a glass flask connected by a double-bent tube; 

 the tube is provided with a stopcock. The cylinder receives the concentrated solution of a radium 

 salt and the glass flask the material which it is desired to render active, or the preparation which 

 it is desired to render phosphorescent. The communication is effected by opening the stopcock and 

 interrupted again by closing it. Both the cylinder and the glass flask are provided with tube and stopper 

 in order that the materials can be changed. 



i s. d. 

 1. 8.0 



0.12.0 

 5. 0.0 



0. 6. 



0. 3. 



0. 8. 



0. 10. 



0. 6. 



0. 12. 



0. 8. 



0. 6. 



1. 0. 



0. 8.0 



Cl. 1967, 3126. 



65* 



