63 Proceedings of Philosophical Societies. [Julv, 



the property of dissolving a good deal of iodine, and acquires in 

 consequence a dark colour. The author conceives this chloride to 

 be a compound of one atom of chlorine and one atom of iodine. 

 In the fourth part the author gave an account of the action of 

 iodine and several of the compound gases. When sublimed re- 

 peatedly in sulphurefed hydrogen gas, a red liquid is formed, which 

 is a compound of the gas and iodine. When dissolved in water, 

 sulphur is deposited, and hydrionic acid formed. When iodine is 

 heated in defiant gas, a very small quantity of a colourless liquid, 

 having an acrid taste, is formed. On nitrous gas and carbonic 

 oxide it produces no change. The fifth part of the paper consisted 

 in experiments on different marine productions, to determine 

 whether they contain iodine. In the sea water of the Mediterranean 

 he did not find any traces of it. He found traces of it, but in 

 very minute quantity, in some fuci and ulvse, but not in any of the 

 confervae or sponges which he examined. In the author's opinion 

 it exists in the ashes of these plants in the state of oxiode of sodium. 

 The most delicate test of iodine he found the property which its 

 salts had of discolouring polished silver. A very minute quantity 

 of it in a salt makes the salt capable of forming a red solution in 

 sulphuric acid. 



At the same meeting a paper by Dr. Kidd, Professor of Chemistry 

 at Oxford, on the formation of nitre on walls, was read. This 

 salt appears spontaneously on the walls of the Laboratory at Oxford, 

 and Dr. Kidd relates the result of his observations on its appear- 

 ance, continued for about a year. The wall is composed of lime- 

 stone, containing '.)6 per cent, of carbonate of lime, and four per 

 cent, of oxide of iron, day, sand, and a trace of magnesia. The 

 nitre only appears on this limestone. Frost increased the rapidity 

 of the formation ; but an intense cold seemed to put a stop to the 

 process. Moisture seemed injurious to the process. The free excess 

 of air was requisite for the formation of the salt in the usual quan- 

 tity ; though a portion was formed on a part of the wall separated 

 from the external air by means of a glass-case ; but after a certain 

 time this formation ceased. Pure carbonate of lime spread upon 

 the glass-case did not yield any saline efflorescence. The saltpetre 

 was nearly pure. It did not contain above half per cent, of lime, 

 and gave very minute traces of sulphuric and muriatic acids. 



On Thursday, the 23d of June, a paper by Sir Humphry Davy 

 was read, on the combustion of diamond in oxygen gas. These 

 experiments were made at Flounce by means of the large burning- 

 glass, which was used in the first combustions of diamond at the 

 expense of the Archduke Leopold. They were afterwards continued 

 at Rome. The oxygen gas was prepared from hyperoxymuriate of 

 potash, and introduced into dry glass globes, fitted with stop-cocks, 

 and capable of holding from 14 to 40 cubic inches of gas. The 

 diamond was put into a small platinum capsule full of holes, and 

 attached to the stop-cock. The absorption of gas was determined 

 by means of a small glass tube properly fitted to the stop-cock, 



