TRANSACTIONS OF THE ACADEMY. 161 



received from Mr. Wm. R. Fisher, of the section of chemistry, 

 which was read and ordered to be filed with the original paper. 

 Professor Ducatel, gave a lecture on the chemical phenomena 

 which occur during respiration, and offered some strictures on 

 the explanation of that function, as described in 'the treatise 

 on Vegetable and Animal Physiology, by P. MarkRoget, M.D.' 



February 11. — Dr. W. E, A. Aikin deposited in the library, 

 'Rennie's Elements of Mechanics.' Mr. W. R. Fisher, read 

 a lecture on 'the detection of arsenic, m medico-legal inves- 

 tigations,' which was accompanied by experimental illustra- 

 tions, of many of the processes and phenomena described. 

 Dr. T. Edmondson, Jr. reported a meteorological table for the 

 month of January, 1S36. Mr. Jas. Green, of the first section, 

 made a report on the steel disc, referred to that section at a 

 former meeting. The experiments of Mr. Green, had afforded 

 him various brilliant colours, resembling in beauty and inten- 

 sity, those produced by the process of M. Nobili, although not 

 arranged with the same precision, in regular forms. The 

 process of the author of tliis species of galvanic etching, has 

 not been disclosed, but there is a prospect, that the conti- 

 nuance of Mr. Green's investigations, will enable him, if not to 

 discover a means identically the same, at least to furnish a 

 mode by which analogous effects may be produced. The 

 report was accompanied by illustrations, exhibiting the man- 

 ner in which the results obtained, had been produced. Mr. 

 Green was requested to continue the investigation. 



Fehruarij 18. — Dr. Geddings presented to the library, a copy 

 of 'Lea's observations on the genus Unio,' and a copy of 

 'Genera Crustaceorum et Insectorum,' by Latreille. 



Professor Ducatel submitted to the Academy, a series of 

 experiments under the direction of Mr. Nicollet, with a view 

 to determine the magnetic intensity at this meridian. He 

 described the manner in v/hich the experiments were per- 

 formed, and exhibited one of the instruments employed. 

 This consists of a highly sensitive magnetic needle, suspended 

 in a glass vessel, by a single strand of silk, perfectly free from 

 any twist, so that no motion may be produced by the torsion 

 of the silk. The intensity was delermined by marking the 

 time, during which any given number of vibrations was 

 accomplished, through a given arc of amplitude ; the tempera- 



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