834 Reflections on the Inadequacy of the principal Hypotheses 



a still greater number of crystallized bodies. I have sought for 

 them in vain in the diamond^ native orpiment, Iceland spar, 

 fluor spar, muriate of soda, carbonate of lead, carbonate of ba- 

 rytes, the sclerotic coat of the eye, the crystalline lens, and a 

 great variety of other bodies, and in some of these with so much 

 care, that they could scarcely have escaped my notice, if they 

 did exist. It therefore still remains to be determined, what 

 kind of crystallization is necessary' to their production, and what 

 relation exists between the magnitude of the rings and the re- 

 fracti\e power of the body which produces them. In some of 

 the experiments already described, the diameters of the rings 

 seem to vary as (m— 1)^; but the anomalies exhibited by amber 

 and nitrate of potash completely prove that this is not the law 

 Wy which their magnitude is regailated. 



I have the honour to be, dear sir. 



Your most obedient humble servant, 

 David Brewster, 

 To Sir Humphry Davy^ LL.D., &c. ^c. 



IN. Reflections on the Inadequacy of the principal Hypotheses 

 to account for the Phcenomena of Electricity. 



[Abridged tVom a Meinoii- read to the Kirwitniaii Society April 1st,, 

 lotli ; May 13th, and June 17tli, 181!.'.] 



By M. Donovan, Esq. Sec* 



A. HE discoveries of late years, made in chemistry by the agency 

 of electricity have given increased interest to electrical investi- 

 gations. It has been supposed that Galvanic phsenomena are 

 produced by electricity; and in order to explain them,. recours* 

 has been had to the hypotheses of Franklin and others. Since 

 then this agent is considered to have so great a share in the 

 operations of nature, it is of some importance that the explana- 

 tions given of its effects should stand the test of reasoning and 

 ©f experiment. It were indeed to be lamented, that the in- 

 teresting series of pliainomena called electro-chemical should 

 depend for explanation on principles not foundetl in fact. Yet 

 such I apprehend is the case. I have occasionally indulged my- 

 self in reflections on the theories of electricity, and I conceived 

 that there is not one of them capable of sustaining even a super- 

 ficial examination. As my objections are for the most part dif- 

 ferent from those which have hitherto been stated by various in- 

 quirers, I thought that to make them known might, perhaps, 

 have some useful tendency. 



* Communicated in its present form by the Author. 



Amidst 



