526 



Professor Lodge 



[May 28 



the cohering of oppositely charged atoms in a chemical compound. 

 When nitrogen and hydrogen are subjected to sparks they unite gra- 

 dually into ammonia. When a brush discharge passes into oxygen 

 it aggregates into ozone, as is well known from the smell near an 

 electrical machine in action. Such actions (especially the latter) do 

 seem to me of the same nature as the aggregation of charged smoke 

 particles, though far more refined. The size of a smoke particle is 

 not great, but it is enormous compared with an atom. Each granule 

 of a lycopodium cloud may be taken as containing pretty exactly one 

 trillion molecules. A smoke particle is a good deal smaller than a 

 lycopodium granule, but not incomparably smaller. It is because of 

 the minuteness and the interleaved arrangement of oppositely charged 

 atoms in a compound, that its electrical cajDacity is so enormous ; so 

 that ten billion units of each kind of electricity can be stowed away 

 among the atoms of a milligram of water, without raising the poten- 

 tial of each above a volt or two.* 



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Two bell-jars as used for smoke and fog condensation in lecture 

 experiments. The one with the point let in at top is for any dry smoke ; 

 the other is for any damp or acid smoke. Insulation is in this latter 

 case quite outside the chamber, and the rod, swathed in glass or gutta- 

 percha, enters through a wide hole in the base-board. The little 

 flask is only to catch drip. The ivory ball is to be illuminated by 

 a beam of light, and to shine through the fog as it clears. 



* In connexion with this part of the subject, see B.A. Report for 1885 

 (Aberdeen), page 744, where an electrostatic tlieory of chemistry is discussed. 



