92 THE ROYAL SOCIETY OF CANADA 



The results were similar to those of the regular and vacuum series 

 up to a temperature of about 450°C. Above this temperature a 

 secondary action appears to influence the results, this being very 

 marked above 600°C. This disturbing influence is no doubt the 

 chemical reaction, well known in connection with gas producers, 

 between steam and carbonaceous matter, whereby carbon dioxide, 

 carbon monoxide, and hydrogen are produced, and the yield and 

 calorific value of the residue decreased. It is quite obvious that the 

 results actually obtained in this series were dependent on the quantity 

 of steam passed through and the duration of the heating. That fairly 

 smooth curves were obtained was due merely to the fact that the quantity 

 of steam and the time of heating were approximately the same in 

 each case. If these had been sufficiently increased, at any rate at 

 the higher temperatures, the coal would have been burned to ash. 



The calorific values shown in the curves were not determined 

 immediately after the experiment. The results to be obtained are so 

 dependent on the quantity of steam passed through, that it was not 

 thought necessary to repeat this series according to the later stand- 

 ardized method. The yield curve is probably correct as it stands, but 

 the calorific value curve, and the results deduced therefrom, are 

 probably uniformly two or three per cent too low. 



Pressure Series: — Eight completed tests were run in this series 

 over a temperature range of from 335°C. to 685°C. The special 

 retort described above was employed, and the general procedure was 

 modified in that the retort was closed so that the volatile products 

 could not escape. When the charge was first heated the pressure 

 rose rapidly to above 120 lbs. per square inch, but the relief valve 

 being opened as required the pressure was reduced and maintained 

 as close to that figure as possible. At the end of the experiment 

 the retort was cooled with the valve shut. 



Trouble was experienced in this series from the water in the 

 coal. In the first place it volatilized and created a big initial pressure; 

 and then, after this had been relieved by the valve, the steam still 

 remaining in the retort gradually passed into the exit tube and con- 

 densed, causing the pressure in the system to fall below the desired 

 minimum. In the second place, the steam in the retort reacted with 

 the coal as described in the previous series, and masked the results 

 it was desired to study. Seven experiments in this series were there- 

 fore carried out using coal briquettes previously dried in carbon 

 dioxide in a toluol oven. In one experiment at 335°C. moist coal was 

 used, the steam effect at that temperature being negligible. 



