54 Mr Townsend, The formation of clouds with ozone. 



and 2 centimetres in diameter, tapering to finer tubing provided 

 with stop-cocks. Inside the tube were two sets of finer tubes (three 



ficl 



of one set and two of the other are shown in the diagram), having 

 wires down their centres to which connection was made by platinum 

 ends sealed in the glass. The platinum ends belonging to one set 

 were twisted together and joined to the terminal^, sealed in the 

 large tube, and those of the other set were similarly joined to the 

 terminal B. The smaller tubes were so arranged that those of 

 one set were in contact as much as possible with those belonging 

 to the other set. When A and B were connected to the secondary 

 of a Ruhmkorff coil and a stream of oxygen passed through the 

 ozonisers a large quantity of ozone was procured. 



Before sending the silent discharge through the oxygen it is 

 necessary to expel the air from the ozoniser by passing a stream 

 of oxygen through it for about an hour. This precaution is neces- 

 sary since ozone prepared from atmospheric oxygen forms a cloud 

 in presence of moisture, which effect has been attributed to the 

 formation of oxides of nitrogen by the discharge. 



3. Having expelled the air from the ozoniser a quantity of 

 oxygen containing ozone was prepared and introduced into the 

 flask F, figure II., by means of the tube A, and no cloud was 



SS 



FlG.II 



observe d over the surface of the water in F. It is desirable to 

 interpose a U-tube of calcium chloride between the tube A. and 

 the ozoniser to prevent any moisture diffusing back into the 

 ozoniser. 



