248 REPORTS ON THE STATE OF SCIENCE. 
tubes and the quicker the flow of gases, i.e., the less the contact action of 
the heated surfaces on the mixing gases, the lower the ignition-tempera- 
ture was found to be. Experiments made between half an atmosphere 
and two atmospheres showed a lowering of the ignition temperature with 
increase of pressure.’ 
In the second method the mixed gases are fired by sudden compression 
in a cylinder, according to Nernst’s suggestion. Photographs have been 
taken on a rapidly moving film of the flames produced by adiabatic com- 
pression. The values found are lower than those given by the first 
method, as was to be expected from the high pressures at which the gases 
are fired. These experiments are being continued. 
Professor Dixon has also continued his experiments on the velocitv 
of sound in different gases heated in a long tube. 
Apart from the new investigations dealt with in the Notes, much 
preparatory work has been done by many of the members. Thus Pro- 
fessor Dalby has refitted the engine—the subject of his experiments—with 
electric ignition, and arranged the end so as to take a new optical indi- 
cator; Professor Bone has made preparations to extend his well-known 
experiments to explosions and combustions where oxygen is present in 
excess; Professor Coker has improved his apparatus for studying wall- 
temperature change; Professor Burstall, in conjunction with Professor 
Hopkinson, has made comparisons between a good mechanical indicator 
and the Hopkinson optical indicator ; Watson, Callendar, and Dalby have 
devoted much study to the improvement of the diaphragm optical indi- 
cator; and Hopkinson and Clerk have improved the operation of their 
piston optical indicators. 
In this Report the sequence of the first Report will be followed as 
far as possible, so that the effect of the year’s work will be readily 
apparent. 
Measurement of the Internal Energy or Specific Heat of Gas at High 
Temperatures. 
No new high-temperature experiments on ‘ Volumetric Heat’ have 
been published, but attention has been devoted to the lower end of the 
scale, as Regnault’s and other standard results were shown last year to 
be in need of revision. This was necessary in order to clear the ground 
for high-temperature work. 
(1) Constant Pressure Experiments up to 100° C. 
It was stated in the first Report that the results of Regnault for the 
specific heat of air at ordinary temperatures, which have hitherto been 
accepted as correct, were materially lower than those obtained by some 
more recent observers. Among these latter researches the most im- 
portant were perhaps those of Mr. Swann,’ the results of whose experi- 
ments, which had not then been published, were communicated to: the 
Committee by Professor Callendar, and gave values about 2 per cent, 
1 Dixon and Coward, ‘ The Ignition Temperature of Gases,’ Jour. Chem. Soc., 
1909. 
? “The specific heats of air and carbon dioxide at atmospheric pressure by the 
continuous electrical method at 20° C. and 100° C.,’ by W. F. G, Swann, A,B.C.S., 
B.Se., Proc. Royal §oc., Series A, vol, }xxxii. 1909, 
