150 Mr Ritchie's examination of the electric 



the ears, Sjcc." and makes it a new subgenus. I have now a 

 specimen of the V. mystacinus in spirits, with a cluster of oramge 

 Caris vesper tilionis, Latr. on each car ; but I do not mean 

 to assert, although I shrewdly suspect, that we only give dif- 

 ferent names to the same thing. Still less would it become me 

 to determine whose nomenclature is the better one, should it 

 be the case. C. Heineken, M. D. 



FuNCHAL, Madeira, 20th October 1829. 



P' S. — Since the above was written, another young Sida alba 

 (but, like the former one, with the bill and claw not serrated) 

 and a young Ajias Crecca have been taken. Several of the 

 latter I saw coming from the N. westward a few days back. 

 I had heard of it as an occasional visitor before. The 

 wind has since, and for a long time previously, been N. 

 easterly. 



Art. XVII. — An experimental examination of the electric and 

 chemical theories of galvanism. * By William Ritchie, 

 A. M. F. R. S., Rector of the Royal Academy at Tain. 



1. The continental philosophers still continue to adopt the 

 electric theory of galvanism proposed by Volta, whilst those in 

 Britain as uniformly follow some modification of the chemical 

 theory proposed by Dr Wollaston. From this diversity of 

 opinion we may safely conclude, that the experimental proofs 

 for the truth of either theory are not sufficiently powerful, to 

 command the assent of all capable of appreciating the weight 

 of such evidence. I have therefore ventured to lay before 

 the Society the following experiments and observations; as 

 they appear to me to establish the truth of some modification 

 of the chemical theory, and to demonstrate the fallacy of the 

 principles on which the electric theory rests. 



2. The fundamental principle assumed by Volta, and sup- 

 ported by his followers, is, that if dissimilar metals be brought 

 into contact they are instantly thrown into opposite electric 



• Phil. Trans, part ii. 1 829. 



