422 Scientific Intelligence. 



graphic axes being similar with respect to all. Moreover the pro- 

 gression according to the atomic weight of the alkali metal is 

 perceptible with regard to the minutest details of the physical 

 phenomena presented by the crystal and is entirely independent 

 of the temperature. It may therefore be finally stated that the 

 whole of the crystallographical properties of the strictly isomor- 

 phous, rhombic, normal sulphates of potassium, rubidium and 

 ccesium, are functions of the atomic loeight of the metal which 

 they contain." — J. Ghem. Soc, lxv, 628-717, July, 1894. 



G. P. B. 



3. On the Influence of Moisture on Chemical Change. — It is 

 well known that certain chemical reactions can take place only in 

 presence of the vapor of water. Baker has extended the number 

 of these reactions and has investigated the conditions under which 

 they take place. His first experiment was made with lime and 

 sulphur trioxide. The lime was prepared by the ignition of pre- 

 cipitated chalk mixed with sugar. While still warm it was 

 placed in a small bulb blown on a tube, at the other end of which 

 some phosphorus pentoxide was placed. The ends of the tube 

 were sealed ; and alter three days, the bulb, which had been heated 

 at intervals to drive any moisture into the pentoxide, was sealed 

 off and introduced into one end of a carefully dried glass tube, 

 some phosphorus pentoxide being placed in the other. This tube 

 after exhaustion was sealed and allowed to stand for two days. 

 One end of it was then connected with a tube containing sulphur 

 trioxide, by means of a joint made of previously ignited asbestos, 

 the point of the sealed end was broken and the trioxide was dis- 

 tilled into the tube. After a week, this portion of the tube con- 

 taining the pentoxide was sealed off and the bulb containing the 

 lime was broken. Not a sign of combination appeared, though 

 on breaking the tube and allowing a little moist air to enter, com- 

 bination at once took place and the mass became vividly incandes- 

 cent. On repeating the experiment with black copper oxide in 

 place of lime, the sulphur trioxide crystallized on the black pow- 

 der, apparently without converting any of it into the white anhy- 

 drous copper sulphate. The action of lime upon ammonium 

 chloride was next examined. This was of interest because water 

 is a product of the reaction. No ammonia gas was evolved on 

 mixing them when the materials were perfectly dried. A mix- 

 ture of dry hydrogen and dry chlorine did not explode when 

 exposed to sunlight ; and more than a quarter of the mixture 

 remained uncombined after exposure to diffused sunlight for two 

 days and to direct sunlight for two days. Nitrogen dioxide and 

 oxygen, when pure and dry, do not react on each other. Care- 

 fully dried hydrogen chloride and ammonia gases do not combine 

 on being mixed. And conversely perfectly dry ammonium chlo- 

 ride does not undergo dissociation when heated to 350°. As to 

 the explanation of these results, the author is inclined to the phy- 

 sical view of the matter suggested by Vernon Harcourt rather 

 than to the chemical one proposed by Dixon. Indeed he has long 



