Chemistry and Physics. 171 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Formation of Ozone. — When an electric discharge was 

 passed in a tube of fused quartz evacuated to a few millimeters 

 of mercuric pressure, it was noticed by E. Goldstein that an 

 intense odor of ozone was produced in the vicinity of the quartz 

 tube. Potassium iodide and starch paper were quickly made blue 

 by the product. The odor disappeared instantly when the dis- 

 charge was interrupted. The phenomenon appeared when the 

 gas pressure in the tube was varied rather widely ; it was most 

 intense when the light from the tube was brightest. Narrow 

 tubes were found to be preferable to wide ones for the purpose. 

 No odor of ozone was perceptible when glass tubes were used in 

 place of those of quartz. The author believes that the phenom- 

 enon is due to the action of ultra-violet rays of very small wave- 

 length, which pass through the quartz glass and convert the 

 oxygen of the air into ozone. 



When a U-shaped quartz tube, through which the discharge 

 was passing, was dipped into liquid air, noticeable ozonization 

 did not appear to take place. It is possible that the ozone in the 

 air surrounding a quartz discharge-tube might have been con- 

 densed by cooling, but it seemed preferable to make the experi- 

 ment with oxygen inside of a tube where the production of ozone 

 would probably be greater. Experiments showed that it was 

 possible to convert oxygen entirely into ozone within a Geissler's 

 tube, which, in this case, was made entirely of glass, by cooling 

 a portion of the tube with liquid air and admitting oxygen 

 from time to time in proper quantities. The cooled part of the 

 tube quickly became coated with a blue layer of liquid ozone. 

 When the tube was removed from the liquid air the blue liquid 

 ran down the walls of the tube and collected at the bottom as a 

 blackish-blue liquid. When a part of the tube was kept cool with 

 liquid air the pressure within the tube fell to about yV mm and this 

 pressure remained constant as long as liquid ozone was present, 

 even when the tube was pumped out as far as possible. This 

 indicated that all of the oxygen was converted into ozone and it 

 showed the tension of ozone at the temperature of liquid air. 

 No spontaneous explosions of the liquid ozone took place during 

 these experiments, such as were observed by Ladenburg when 

 ozone was condensed under atmospheric pressure. — Perichte, 

 xxxvi, 3042. H. l. w. 



2. A Peculiar Property of Some Hydrated Salts. — A. de 

 Schulten observes that, as a general rule, where salts form 

 several hydrates, the hydrate richest in water gives the lower 

 hydrates by successive increases in temperature. For instance, 

 MgS0 4 *12H 2 0, at a few degrees above freezing is changed to 

 MgS0 4 -7H 2 0, while at 52° MgS0 4 -6H 2 is formed, and at 132° 



