474 Scientific Intelligence. 



atomic mass of hydrogen 1*0085 (O = 16) ; or calling the atomic 

 mass of hydrogen 1, the value 15*866, practically 15*87 as the 

 atomic mass of oxygen. The atomic mass of hydrogen has been 

 found by Stas to be 1*0075, by Cooke and Richards 1*0083, by 

 Noyes 1*0072, by Lord Rayleigh 1*0069 and by Keiser 1*0032. — 

 Chem. News, lxvii, 54, 68, 77, 90, 104, 115,126, 139, 151, 164, 

 1893. G. F. B. 



2. On the Constitution of Hydrogen peroxide and of Ozone. — 

 In 1886, Teaube expressed the opinion that hydrogen peroxide 

 contains its oxygen atoms doubly united, so that this substance 

 is a compound of an oxygen molecule with two hydrogen atoms, 

 H 2 . O = O. In support of this view he now brings forward cer- 

 tain significant facts. In the first place, no instance is known of 

 the formation of hydrogen peroxide by the oxidation of water, 

 the author's experiments showing that it is produced syntheti- 

 cally only by the action of molecular oxygen upon hydrogen. 

 Thus it is formed at the kathode of the voltameter, where the 

 evolved hydrogen meets gaseous oxygen. It is produced in 

 processes of slow combustion, as in the case of zinc for example, 

 where the hydrogen set free from the water comes in contact 

 with ( oxygen gas. It is also generated by the combustion of 

 hydrogen and also by the action of hydrogen palladium upon 

 oxygen. In the second place, hydrogen peroxide exerts an oxi- 

 dizing action only upon strongly reducing substances, being then 

 rearranged into two hydroxy! groups which unite directly ; 

 Zn + H 2 2 = Zn(OH) 2 . That these hydroxyl groups do not pre- 

 exist in the peroxide appears to the author to follow from the 

 complete indifference which this substance shows compared with 

 other oxidizing agents. Thus Schonbein found that it does not 

 react at once upon either phosphorus or phosphorus acid. 

 Welzien states that the titer of a peroxide solution did not 

 change after standing over phosphorus for two months ; and 

 Schonbein observed that this substance could even be distilled 

 with ether without decomposition. In alcohol, according to 

 Lustig, the peroxide remains unaltered even in presence of sul- 

 phuric acid. In very dilute solution, it liberates iodine from 

 potassium iodide only very slowly and potassium oxalate may be 

 boiled with it without being oxidized. In further proof that 

 hydrogen peroxide does not consist of two hydroxyl groups, the 

 author notes the fact that, were this the case it should be ob- 

 tained by the electrolysis of barium hydroxide; whereas no trace 

 of it is produced in this process, only ordinary oxygen appearing 

 at the anode. Ozone resembles hydrogen peroxide in many re- 

 spects. If the constitution of the latter is H-O-O-H, that of the 



latter must be JZ. , its three atoms having the same chemical 



value. But if hydrogen peroxide is H 2 .0 = and ozone 

 O . O = O the doubly united atoms will react differently from the 

 third atom. This latter case appears to be the fact. Thus when 

 ozone acts on sulphurous oxide S0 2 -f-0 3 = S0 3 + 5 . Moreover 



