Chemistry and Physics. 77 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Hydrides of the Alkaline Metals. — Having previously- 

 prepared and described the colorless, crystalline hydrides of 

 potassium and sodium, KH and Natl, Moissan, in continuing 

 this line of work, has found that hydrides of caesium and rubi- 

 dium exist, CsH, and RbH, and that these have entirely similar 

 chemical and physical properties. The author gives some general 

 reactions of these interesting compounds. They are all powerful 

 redueing-agents, and decompose water in the cold with the evol- 

 ution of hydrogen : 



RH + H 2 = ROH + H 2 . 

 They decompose also the hydrogen acids : 

 RH + HC1 = RC1 + H 2 

 RH + HCOOH=HCOOR + H 2 . 

 They react with gaseous ammonia : 



RH + NH S =NH 2 R + H 5 . 

 When heated very gently in the presence of carbon dioxide they 

 yield alkaline formates : 



RH + C0 2 =HC00R 

 and upon slightly raising the temperature they give mixtures of 

 formate and oxalate : 



2KH + 2C0 2 =K 2 C 2 4 + H, 

 Further, an alkaline hydride when heated in an atmosphere of 

 carbon monoxide gives a slight deposit of carbon, and is par- 

 tially transformed into formate : 



2CO + KH = HCOC>K + C. 

 Sulphur dioxide reacts at ordinary temperatures, under certain 

 conditions of pressure, with the production of hydrosulphites : 



2RrI + 2S0 2 =R 2 S 2 4 + H 2 . 

 Certain organic compounds containing halogens react with the 

 alkaline hydrides at temperatures above 150° : 



RH + C 2 H 5 I = C 2 H e + RI; 



RH -f CH 3 C1 = CH 4 + RC1. 

 In contact with cyanogen gas in the cold they give cyanides and 

 hydrocyanic acid : 



RH + C 2 N 2 = RCN + HCN. 

 With acetylene at ordinary temperatures the following reaction 

 takes place : 



2RH + 2C 2 H 2 =:C 2 R 2 .C 2 H 2 + 2H„ 

 and, when gently heated, the double compound gives off acety- 

 lene and leaves a carbide, C,R 2 . 



The author has shown, further, that the alkaline and alkaline 

 earth hydrides do not conduct electricity and cannot be classed 

 with the alloys. Consequently, in its combinations hydrogen 

 ought not to be considered as a metal. — Ann. Chim. Phys., VIII, 

 vi, 289. h. l. w. 



