1893 - 94 .] S. Kimura on Electrical Proiierties of Gases. 207 
that before the sudden escape of the gas the thermo-electric current 
runs through the hotter junction from the charged iron towards the 
normal iron, but after the escape reverses its direction. I regret 
that I did not verify this by direct experiment, i.e., without the use 
of the third thin wire. 
The COg-iron (&, PI. I.) behaved like ordinary iron, but be- 
tween 140° and 150° the gas seemed suddenly to escape. From 
150° to 250° it reached a second time a stable condition. The 
cooling curve also lay above the heating curve, and cut the latter at 
the temperature where the gas escaped. 
The accompanying curves (PL I.) show the relation between the 
temperature of the hotter junction in centigrade and the electro- 
motive force between thin iron and the charged iron wires on an 
arbitrary scale of deflections. The temperature of the hotter junc- 
tions were first measured by the thermometric current, and then 
reduced to the centigrade scale. The galvanometer was gauged at 
the beginning of each experiment. In the experiment with the 
CO-iron, the cold junction was kept at 15°-8 ; and in the case of the 
C02-iron, the cold junction was kept at 20°*5. 
To sum up, iron saturated with carbonic oxide or carbonic acid 
gas behaves thermo-electrically as a metal until a certain temperature 
is reached. At this temperature the gas begins to escape till a 
certain other temperature is reached ; and from this up to higher 
temperature the metal is in a new stable condition. During cool- 
ing, however, the iron recovers a part of the gas, and remains stable 
throughout. The cooling curve intersects the heating curve at 
about the mean temperature corresponding to the escape of gas. 
In CO-iron, gas escapes at between 180° and 190° C. The 
thermo-electric current flows through the hotter junction from CO- 
iron to the normal iron at a temperature lower than the critical 
temperature just named, but above this temperature it flows in an 
opposite direction. After partial recovery of the gas on cooling, the 
current is very feeble. 
In C02-iron, the gas escapes at between 140° and 150° C. Here 
there is a suggestion that the wire on cooling recovers the gas more 
than it can sustain in that high temperature, so that the curve 
shows a swelling up at the beginning of cooling. I observed the 
same phenomenon in many other experiments on hydrogenised 
