194 Suggestion for eslalUshiDg a Telegraphic 



fluor spar and concentrated sulphuric acid of commerce, in 

 vessels of lead. Oxygen and hvdroi^en were evolved, and a 

 dark brown matter separated at the deoxidating surface ; but 

 the result of an operation conducted for many hours, merely 

 enabled me to ascertain that it was combustible, and pro- 

 duced acid matter in combustion ; but I cannot venture to 

 draw the conclusion that this acid was fluoric acid, as it was 

 not impossible that some sulphureous, or sulphuric acid 

 might likewise exist in the solution. 



I heated the olive-coloured inflammable substance, ob- 

 tained from the boracic acid, in connnon fluoric acid gas in 

 a plate glass retort ; the temperature was raised till the glass 

 beiian to fuse; but no change, indicating a decomposition, 

 took place. 



I heated six grains of potassium with four grains of por/- 

 dered fluor spar in a green glass tube filled with hydrogen; 

 there was a slight ignition, a minute quantity of hydrogen 

 gas was evolved, and a dark gray mass was produced, which 

 acted upon water with much effervescence, but left no solid 

 inflammable residuum. 



[To be contiiiiiefl.] 



XVI. Suggestion for establishing a Telegraphic Intercourse 

 between London and Duidin. By the Rev. Mr. James 

 Hall. 



To Mr. Tilloch. 



PiR, As it is the duty of every good subject to contribute 

 what he can to the service of his country, I have ventured 

 to trouble you with the following hints on the subject of 

 telegraphs. 



Previous to mv setting out for Ireland, (through the 

 irreater part of which I travelled lately,) I began to study the 

 phvsical geography of that country. On turning my atten- 

 tion to this "matter, and conversing with Dr. Thomson of 

 Kensin<'lorj Gravel Pits, and others, on the subject, the 

 Doctor drew my attention to the circumstance, that the old 

 n'.aps of Ireland, particularly those of the lificcnth century, 

 and about the time of the Spanish armada, laid down the 

 northern parts of that kingdom n)uch nearer the Mull of 

 Cantire, in Scotland, than the modern maps in general do. 

 The question then was. Whether the maps of Ireland of the - 

 fificenth, or those of the present century, are the more cor- 

 rect? On arriving at Torr Point, Fair Head, the nearest 

 point of Ireland to Scotland, I hired a boat and sailed to 



Cantire, 



