530 Mr. J. S. G. Thomas on 



value of the ratio at higher values of the rate of heat- supply 

 in the cases of coal-gas and hydrogen than is the case with 

 air, is to he attributed to the relative effects in their cases of 

 the loss proportional to 6b being somewhat greater compared 

 with their respective losses /(#&) than is the case with air. 

 This is explainable in terms of the relative diathermancies, 

 conductivities, specific heats, and densities of the respective 

 gases, but it is unnecessary to pursue the point further 

 here. 



The results obtained for the calibration for a bare hot-wire 

 anemometer in the cases of dry air (three results), air saturated 

 with water vapour at atmospheric temperature (two results), 

 carbon dioxide, and oxygen are shown in Plate XIII. fig. 17. the 

 bridge-current being 1*3 amp. in each case. In Plate XIII. 

 fig. 18 the results are given for the calibration of a glass- 

 coated anemometer wire in streams of dry air, coal-gas, and 

 hydrogen. The curves obtained with nitrogen using a 

 bare wire anemometer were practically the same as those 

 for air and are omitted from the diagrams for the sake of 

 clearness. The curve obtained for the calibration of bare wire 

 anemometer No. 2 in air using same current 1*3 amp. is 

 added to fig. 18, for sake of comparison. The various 

 gases passing through the flow-tube were sampled and their 

 compositions ascertained with the following results : — 



per cent. 



Sample of C0 2 C0 2 97'0 



O 05 



N (cliff.) 2-5 



Sample of N 2 CO., 



O, 02 



]N T 2 99-8 



Sample of 2 C0 2 



2 96-0 

 N 2 ' 4-0 



Sample of H 2 .. H 2 99"8 



Sample of Coal-gas C0 2 2'0 



2 02 



Cnllm 8-2 



CO 76 



CH 4 30-5 



H 2 480 



N 2 (cliff.) 8-5 



