364 Sir W. Snow Harris on the Laws and Operation [June 16, 



reduced in the course of the circulation, oxidizing a portion of the sub- 

 stances derived from the food or of the tissues. The purplish colour now 

 assumed by the solution illustrates the tinge of venous blood, and a fresh 

 shake represents a fresh passage through the lungs. 



XIX. " Further Inquiries concerning the Laws and Operation of Elec- 

 trical Force." By Sir W. Snow Harris, F.R.S., &c. Received 

 June 8, 1864. 



(Abstract.) 



1. The author first endeavours to definitely express what is meant by 

 quantity/ of electricity^ electrical charge^ and intensity. 



By quantity of electricity he understands the, actual amount of the un- 

 known agency constituting electrical force, as represented by some arbi- 

 trary quantitative * electrical ' measure. By electrical charge he under- 

 stands the quantity which can be sustained upon a given surface under a 

 given electrometer indication. Electrical intensity^ on the contrary, is 

 * the electrometer indication ' answering to a given quantity upon a given 

 surface. 



2. The experiments of Le Monnier in 1746, of Cavendish in 1770, and 

 the papers of Volta in 1779, are quoted as showing that bodies do not take 

 up electricity in proportion to their surfaces. According to Volta, any 

 plane surface extended in length sustains a greater charge, — a result which 

 this distinguished philosopher attributes to the circumstance that the elec- 

 trical particles are further apart upon the elongated surface, and conse- 

 quently further without each other's influence. 



3. The author here endeavours to show that, in extending a surface in 

 length, we expose it to a larger amount of inductive action from surround- 

 ing matter, by which, on the principles of the condenser, the intensity of 

 the accumulation is diminished, and the charge consequently increased ; so 

 that not only are we to take into account the influence of the particles on 

 each other, but likewise their operation upon surrounding matter. 



4. No very satisfactory experiments seem to have been instituted showing 

 the relation of quantity to surface. The quantity upon a given surface has 

 been often vaguely estimated without any regard to a constant electro- 

 meter indication or intensity. The author thinks we can scarcely infer from 

 the beautiful experiment of Coulomb, in consequence of this omission, that 

 the capacity of a circular plate of twice the diameter of a given sphere is twice 

 the capacity of the sphere, and endeavours to show, in a future part of the 

 paper (Experiment 16), that the charge of the sphere and plate are to each 

 other not really as 1*2, but as 1:^2, that is, as the square roots of 

 the exposed surfaces ; so that we cannot accumulate twice the quantity of 

 electricity upon the plate under the same electrometer indication. 



5. On a further investigation of the laws of electrical charge, the quan- 

 tity which any plane rectangular surface can receive under a given intensity 



