206 Proceedings of the British Association for [Sept. 



use of this salt is not applicable to the alcoholic prussic 

 acid. 



25. Mr. Johnston made some observations on the iodides 

 of gold, which he had analyzed. Their composition is similar 

 to the chlorides. Previous errors, he found, were to be 

 ascribed to the precipitation of an excess of gold, when 

 ammonia was employed in the analysis. 



There are three compounds, viz. (1.) Au I ; (2.) Au 3 I ; 

 (3.) Au 3 I 4- K I, the atom of gold being 25. 



26. Dr. William Barker made some observations on the 

 passage of electricity along a platinum wire. Black spots 

 were observed at regular distances, the rest of the wire 

 being luminous. 



27. Mr. Scanlan exhibited a beautiful specimen of hema- 

 tine crystallized in the centre of a mass of logwood. 



Mathematics and Physics. — Monday, \Oth August. Dr. 

 Robinson, President; Mr. Baily, Sir T. Brisbane, 

 Vice-Presidents ; Prof. Wheatstone, Prof. Hamilton, 

 Secretaries ; Prof. Mosely, Mr. Whewell, Prof. Lloyd, 

 Dr. Drummond, Dr. Knight, Mr. Murphy, Mr. G. 

 Rennie, Prof. Stevelly, Mr. Cooper, Mr. Wharton, 

 Dr. Lloyd, Mr. Maccullagh, Mr. Sadlier, Mr. Fox, 

 Mr. Snow Harris, Prof. Powell, Dr. Dalton, Lord 

 Adare, LoRDOxMANTOWN,Capt. Sabine, Prof. Babbage, 

 Dr. Lardner, Col. Colby, Sir J. Franklin, Capt. James 

 Ross. 



1 . Mr. Whewell read his report on the state of our know- 

 ledge respecting the application of mathematical and dyna- 

 mical principles, to magnetism, electricity, heat, &;c. 



He observed that Newton's anticipation that all physical 

 forces are to be explained by some application of the princi- 

 ples of dynamics, is verified by the subsequent progress of 

 science, and that the only legitimate theories of heat, elec- 

 tricity, magnetism, &c., are such as are founded on nume- 

 rical results, reduced to laws. This has been, in a great 

 measure, accomplished ; and, therefore, mechanical reason- 

 ing is applicable. 



He then compared the two theories of electricity, notic- 

 ing the application of the higher analysis by Poisson, Mr. 

 Snow Harris's valuable numerical results, Barlow's Laws of 



