116 Prof. Magnus on the Influence of the 



100 millims. In addition to the above gentlemen, Dr. Kundt, 

 whose help I have had the advantage of having in this investi- 

 gation, has convinced himself of the accuracy of these statements. 



From these experiments it follows that the radiation of trans- 

 parent aqueous vapour (that is, of aqueous vapour in the proper 

 sense of the term) is far smaller than that of carbonic acid or of 

 coal-gas, and but little more than that of dry atmospheric air. 

 Hence it follows that the absorptive power of air which contains, 

 or is saturated with, transparent vapours, differs little from that 

 of dry, and that it is only if air is misty (that is, contains con- 

 densed vapour) that it radiates and equally well absorbs heat. 



The vapours of most other liquids are oxidized when they 

 pass through the tube mixed with atmospheric air, or if, while 

 heated, they pass into the air. With especial facility are the 

 vapours of ether oxidized. When air passed through ether at 

 the ordinary temperature of the room (15° C), on emerging from 

 the heated tube the odour of aldehyde and of acetic ether could 

 be at once perceived ; at the same time the thermometer over 

 the tube rose considerably, indicating a continued oxidation out- 

 side the tube. Corresponding to this heating, the deflection of 

 the galvanometer was so great that it could be no longer ob- 

 served. 



When air passed through absolute alcohol at 15° C, the de- 

 flection of the galvanometer amounted to about 30 millims. 

 only. Heated to its boiling-point, the deflection rose to 80 to 

 100 millims. Here also there was an oxidation, but, as com- 

 pared with that of ether, it was but small. The thermometer 

 also was unchanged, whether the air emerged from the tube free 

 from vapour or saturated with aqueous vapour. 



As regards temperature, the behaviour was the same in the 

 case of the following liquids. 



When air passed through amylic alcohol, it produced a scarcely 

 perceptible deflection of the galvanometer. As this alcohol only 

 boils at 130° to 132° C, but little vapour is formed on passing 

 air through it. If, while the air passed, it was heated almost to 

 its boiling-point, a deflection of 60 to 80 millims. ensued. 



Methylic alcohol, which boils at 65°, produced a deflection of 

 60 millims. when used at 15° C.j if used at its boiling-point, 

 the oxidation was so considerable that no observation could be 

 made. 



When the air passed through cold acetic ether, the deflection 

 amounted to 30 to 50 millims. If heated to its boiling-point, it 

 was 200 to 220 millims. 



Through boracic ether at 15° a deflection of 30 millims. was 

 obtained; heated to its boiling-point it was 100 to 110 millims. 



It appeared superfluous to investigate a greater number of 



