Chemistry and Physics. 395 



amount of ozone formed from the contraction observed, the 

 authors introduced some turpentine into the apparatus and noted 

 the absorption. It amounted to about 11 "7 per cent of the orig- 

 inal volume of the oxygen. Another cylindrical tube provided as 

 above with the cylindrical bulb and lateral reservoir containing 

 phosphoric oxide, but also containing a small bulb of pure 

 mercury, was filled with pure oxygen and electrified, and the 

 bulb broken. The surface of the mercury lost its convexity and 

 the mercury adhered strongly to the glass. In 24 hours, how- 

 ever, no signs of oxidation appeared on the mercury and after a 

 few days it returned to its original condition, no trace of ozone 

 being detectible within the apparatus. Hence the authors con- 

 clude that perfectly dry ozone is completely decomposed by mer- 

 cury without oxidation of the metal. In order to study the 

 -character of the silent discharge, two strips of tin-foil were 

 placed on the remote sides of sheets of patent plate glass, and 

 these were mounted on the jaws of a small parallel vise, so that 

 they could be moved to or from each other. At one centimeter 

 distance, the discharge consists of a few noisy sparks. As they 

 are approached the sparks diminish and the glow discharge in- 

 creases, till at a millimeter, the glow greatly predominates. If 

 now a little warm moist air be blown between the plates the glow 

 vanishes, the discharge again consisting of a few large sparks. 

 Hence it would appear that the high yield of ozone in dry oxygen 

 is due to the fact that the condition of the interior surfaces of the 

 apparatus are exceedingly favorable to the occurrence of the most 

 efficient form of electric discharge. 



In a subsequent paper, Shenstone and Cundaix described a 

 simple form of apparatus for showing as a lecture experiment, 

 Loret's proof of the composition of ozone, which consists in sub- 

 mitting a fixed quantity of oxygen to the action of the electric 

 discharge and of turpentine in succession and of observing the 

 changes of volume which occur. A somewhat wide tube has the 

 neck of a cylindrical bulb sealed into its upper end while its 

 lower has two lateral openings, one of considerable size closed by 

 a cork, the other connected to a tube passing vertically upward 

 parallel to the large tube and closed with a tap. Near the top of 

 the wide tube and on the opposite side is a re-curved tube filled 

 with sulphuric acid colored by indigo, serving as a manometer. 

 A bulb containing turpentine is introduced into the tube through 

 the lateral tubulure, the apparatus is filled with oxygen, immersed 

 in cold water, and the electric discharge passed between sulphuric 

 acid contained in the cylindrical bulb and a strip of tin-foil on the 

 outside of the main tube. The change of level in the liquid in 

 the manometer shows the contraction. By shaking the apparatus 

 the turpentine bulb is broken and the absorption of the ozone is 

 effected.— J". Chem. Soc, li, 610, 625, July, 1887. G. f. b. 



2. On the Density of Nitrogen dioxide and of Nitrogen tetr ox- 

 ide at -100°. — In the hope that at very low temperatures, the un- 

 saturated molecules NO and N0 2 dissociated at ordinary tempera- 



