Section of Chemistry and Electricity. 589 



in the Chemical School of Trinity College, Dr. Barker observed that 

 on passing the current of electricity through a piece of platina wire, 

 about three feet in length, and igniting it, there were dark portions 

 of the wire of about -J- or £ an inch in length at intervals of from 

 three to four inches in its whole length, the same parts of the wire 

 being in the same condition during the time that the wire remained 

 ignited. The author was unable at the time, owing to the number 

 of experiments to be tried with the battery, to take any measure- 

 ments or to examine whether wires of different diameters were dif- 

 ferently affected. The fact was stated for the consideration of the 

 section, reserving for further examination the law by which the di- 

 stances and dimensions of these unignited portions of the electrified 

 wire are governed, whether their distances are constant, or vary ac- 

 cording to the size and material of the wire employed or the quan- 

 tity or intensity of the galvanic currents. 



An Account of some Experiments recently made on the Buoys in 

 Kingstown Harbour, with a view to protect from the action of Sea 

 Water the Metals, and especially the Iron-work, attached to 

 them. By Edmund Davy, F.R.S.,M.RJ.A., fyc, Professor of 

 Chemistry to the Royal Dublin Society. 



Last year an enlightened member of the Royal Dublin Society, 

 Mr. John M'Mahon, made the author acquainted with the fact that 

 the iron-work attached to the new buoys lately put down in Kings- 

 town Harbour had undergone a very rapid corrosion by the action 

 of sea-water on it; and shortly after, the Commissioners of Public 

 Works acting as Commissioners of Kingstown Harbour directed 

 his attention to the subject, with the view of ascertaining the cause 

 of such corrosion, and the means of prevention. 



The new buoys* are precisely similar to the buoys, of the most 

 approved construction, now used in Portsmouth Harbour. The 

 whole surface of each buoy is sheathed with copper, except the bot- 

 tom and about three inches of the smaller end, which is covered 

 with lead, fastened to the copper by metal nails. A bolt passes 

 through the whole length of the buoy, and is terminated at each end 

 by a shackle. The lower shackle has a bridle patent chain fastened 

 to it by means of a bolt and a thin pin called a forelock, which is 

 such an important part that on its preservation mainly depends the 

 security of the ships moored to the buoyf. The bridle chain is se- 

 cured to a larger chain-cable and moorings, by means of shackles, 

 bolts, and forelocks. The forelocks require to be examined about 

 once a year, and replaced if defective. The bolt, shackles, chains, 

 and forelocks are all of the best wrought iron. 



On examining the buoys the author found all the iron-work at 

 and near their bottoms very much corroded ; and the corrosion ap- 



• The author exhibited a drawing of one of these buoys, 

 t Some years since the Lord Lieutenant's yacht broke from her moorings 

 in Kingstown Harbour in consequence of the defective state of the forelock. 



