1815.] that prevent Vessels from entering Harlours. 20/ 



Thus Plate XXXI. fig. 11, 



a, a, the river flowing into the sea. 



I, I, b, sand or gravel, being the object of removal. 



c, c, c, the rock. 



d, d, d, the tunnel formed in the rock by mining. 



e, e, e, large augur holes, according to circumstances. 



In this way I expect several new harbours might be formed, old 

 ones deepened, cleaned, &c. ; and eventually, in all likelihood, 

 many of those dangerous bars, such as Dublin and Linmouth, 

 removed. 



Letting the tide flow into a part of a harbour, and then shutting 

 it in by gates, might frequently be resorted to as a means of 

 obtaining a stream of water. 



I remain yours truly, 



John Rook, Jun. 



jikehead, Wigton, Cumberland, 

 Dec. 20, 18U. 



P. S. I should wish to hear the opinion of any engineer upon 

 the above. 



Article VIII. 

 A Memoir on Iodine. By M, Gay-Lussac. 



{Conlinucd from p. 109.) 



Azote does not combine directly with Iodine. We obtain the 

 combination only by means of ammonia. It was discovered by M. 

 Courtois. I shall give it the name of ioduret of azote. It has 

 been accurately analyzed by M. Colin, and I shall briefly state 

 from bim the circumstances of hs formation and its nature. 



When ammoniacal gas is passed over iodine, a viscid shining 

 liquid is immediately formed, of a brownish black colour, which, 

 in proportion as it is saturated with ammonia, loses its lustre and 

 viscosity. No gas is disengaged during the formation of this liquid, 

 which may be called ioduret of amntonia. It is not fulminating. 

 When dissolved in water, a part of the ammonia is decomposed ; its 

 hydrogen forms hydriodic acid ; and its azote combines with a 

 portion of the iodine, and forms the fulminating powder. We 

 obtain the ioduret of azote directly by putting iodine in fine powder 

 into a solution of iiramonia in water. This indeed is the best way 

 of preparing it ; for the water is not decomposed, and seems to 

 concur in the production of this ioduret only by determining the 

 formation of hydriodate of ammonia. 



Tlie ioduret of azote is pulverulent, and of a brownish blflck 

 colour. It detonates from the smallest shock, and from heat with a 

 feeble violet colour. I have often seen it detonate spontaneously 

 when properly prepared. When [>ut into pota'>)i, azote is dis- 



