528 REPORT—1904. 
confined to the layer of gas immediately in contact with the hot surface, and we 
therefore measured the rate of change in a heterogeneous system. Our results may 
be summarised as follows :— 
1. With normal electrolytic gas the velocity of steam formation is always 
directly proportional to the pressure of the ‘dry’ gas in the apparatus. In other 
words, the velocity of chemical change is in no way determined by the ‘ order’ of 
the reaction. : 
2. With excess of either hydrogen or oxygen the velocity of steam formation 
depends mainly, if not entirely, on the pressure of the hydrogen in the apparatus. 
} 3. The catalysing power of the surface is always stimulated by previous 
exposure to hydrogen at 430°. Previous exposure of the surface to oxygen at the 
same temperature has the opposite effect. 
4. The catalysing power of the surface is not affected by previous exposure to 
hydrogen at a red heat, followed by continued exhaustion at the same temperature. 
This proves that the stimulating effect of hydrogen at 43U° is not attributable to 
a chemical reduction of the catalysing material. 
5. At a red heat porous porcelain has the power of absorbing considerable 
quantities of hydrogen, of which only a part is yielded up on continuous exhaustion 
at the ordinary temperature. 
6, The results are substantially the same, whether the catalysing surface be acid 
or basic in character. 
The experiments indicate that the velocity of steam formation depends on an 
association of the hydrogen with the catalysing surface. 
4, The Decomposition and Synthesis of Ammonia. 
Sy Epvcar Puinie Perman, D.Se. 
it is well known that on heating ammonia a large proportion of it is decom- 
posed, and it has been assumed by many chemists that the mixture then comes 
into chemical equilibrium. Some experiments recently carried out by Mr. G, A.S. 
Atkinson and myself appear to disprove the existence of any equilibrium in the 
case, 
Decomposition of Ammonia by Heat. 
In a recent communication! it was shown, from observations on the rate of 
decomposition of ammonia heated in a porcelain globe, that there is no equilibrium 
until complete (or nearly complete) decomposition has taken place. 
Direct Synthesis of Ammonia by Heat. 
In order to solve the question of equilibrium it was thought better to attempt 
to reach the equilibrium point (if one exists) by synthesis. A mixture of nitrogen 
and hydrogen (1:3) was passed slowly through a red-hot glass tube into dilute 
acid; on making the solution alkaline and testing for ammonia by Nessler’s solu- 
tion no trace was found. The result was similar when the tube was packed 
with broken porcelain. If, however, the mixture was passed over red-hot iron 
(and many other metals), or over asbestos, pumice, or clay tobacco-pipe stems, 
traces of ammonia were formed. These last-named substances contain iron, and it 
is concluded that there is no combination of the nitrogen and hydrogen unless 
some catalysing agent is present. 
Decomposition and Synthesis of Ammonia by Electricity. 
On sparking a mixture of nitrogen and hydrogen traces of ammonia were 
formed, and the gases came into equilibrium in about halfan hour. Approxi- 
mately the same equilibrium point was reached on decomposing ammonia by 
sparking, but when the volume was kept constant many hours’ sparking were 
required to reach that point. 
! Proc, Roy. Soc., 1904, 74, 110. 
