200 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



changed it a point of the greatest importance in connection 

 with the construction of ships and boilers, since if, as is prob- 

 able, the saturation of iron with hydrogen takes place when- 

 ever oxidation goes on in water, then the iron of boilers and 

 ships may at times be changed in character and rendered 

 brittle, in the same manner as Mr. Johnson's wire. 12 A, 

 1874, IX., 396. 



MANUFACTURE OF OXYGEN GAS. 



In the manufacture of oxygen gas from chlorate of potash, 

 J. Lowe recommends the use of freshly ignited ferric oxide 

 (the variety once known as caput mortuwn) instead of the 

 black oxide of manganese. It should be very intimately 

 mixed with the chlorate. There is said to be greater speed 

 attained in the operation, while the danger of an explosion 

 becomes less. 18 (7, March 18, 1874. 



IS HYDROGEN A METAL? 



The discussion concerning the presumable metallic nature 

 of hydrogen, which is periodically renewed, has received 

 fresh impulse from some discoveries recently made by MM. 

 Troost and Hautefeuille, who announce that hydrogen forms 

 a definite chemical compound with two equivalents of either 

 sodium or potassium. Potassium, when heated to 200, will 

 combine with hydrogen, but at 900 the compound is entirely 

 destroyed. The newly discovered compounds present all the 

 characteristics of amalgams the metallic lustre and physical 

 appearance of a metal. The authors therefore urge that 

 these hydrides of sodium and potassium are true alloys, and 

 consider their existence as a new proof that hydrogen is a 

 metal. Another discovery of similar tenor, by the same in- 

 vestigators, is the fact that palladium forms with hydrogen 

 a definite compound, with the formula Pd 2 H; that this com- 

 bination can dissolve hydrogen gas like platinum, and in 

 variable quantity, according to its physical condition. This 

 property of the palladium alloy, according to the authors, 

 explains the want of uniformity of the numerical results ob- 

 tained by Graham, the originator of this method of inquiry, 

 according as he employed the palladium as wire or in the 

 form of sponge. 



