304 Hoijal Society. 



crease. By using a lens instead of a flat glass, coloured fringe? 

 are seen : with the first lens the colours appear in a line j when 

 the second lens is added to it, the fringes of colours then assume 

 £. circular form ; when a third is applied, a new series of coloured 

 fringes appear, which the author calls intcrscctionary fringes. 

 Coloured rings also appear in these experiments, the same as in 

 Dr. Herschel's researches. Mr. K. used a l>lack card, the same 

 r.s Dr. H. He also painted the under side of his glasses, in order 

 to prevent the appearance of coloured concentric rings, and the 

 better to observe the nature and modulations of the fringes, which 

 iiad not been observed, by ])reccding experimenters, and of which 

 he endeavoured to make tolerably accurate drawings. The au- 

 thor very modestly avoids drawing any liasty general conclusions 

 from his experiments, but seems to think that reflection and re- 

 fraction are sufiicitnt to explain all the pha^nomeua of coloured 

 concentric rings, by the solution or separation and combination 

 oif rays without any intervening plate of air, or fits of easy trans- 

 mission, as supposed by Newton. He found that in vacuo, i:i 

 water, or in air, the same rings \vere produced ; but nitric and 

 other heavy acids destroyed both tlie rings and colours. 



Baron Von Humboldt of Berlin, and Messrs. Biot and Gay 

 Lussac of Paris, were severally elected this evening (being the 

 first meeting after Easter) foreign members of the Society. 



April 13. The veteran Major Rennel furnished another long 

 paper on the subject of currents in St. George's Channel, in addi- 

 tion to and illustration of his former paper publislied above twenty 

 years ago (17^3) on this subject. He chiefly dwelt on a NW 

 current proceeding from Cape Fiaisterre to Cape Clear and the 

 Scilly Isles ; his facts were taken from old journals kept on dead 

 reckonings in 1737, and some books on navigation published in 

 1755. He also mentioned the experiment of a bottle being 

 carried bv a NE current to Ca])e Ortcgal, &c. 



April 20. Part of a very curious and hnportant paper by Sir 

 H. Davy was read, detailing some of his new and curious ex- 

 periment, and discoveries on the combinations of iodine with 

 oxvgen and the acids. It ai)pears that when oxygen is com- 

 bined with iodine, it first assumes a pastey or gelatinous appear- 

 ance, and afterwards becomes solid ; witii sulphuric and nitric 

 acids something similar occurs : these solid combinations Sir H. 

 very properly calls oxviodats, as they diifer very materially from 

 all the other salts the names of which terminate in ale. Gay 

 Lussac, however, having anticipated the existence of such bodies, 

 proposed to call them iodates ; but this name. Sir H. justly ob- 

 serves, CO! vcys a "ery erroneous idea of their real character, which 

 is singular and interesting. The colour of these salts approaches 

 to violet, according to the quantity of uncombined iodine pre- 

 sent in tliem. Roy.vL 



