]g]5.] Royal Society. 45'i 



competent, it occurred to him that it would be satisfactory to the 

 Society to lay before tliem the results which have been obtained by 

 an investigation into the ships built according to his mode. He 

 stated the report of Admiral Durham respecting the Tremendous. 

 She was the best sailing ship in his fleet. Three j'ears afterwards 

 she was examined by professional ship-builders, and found 

 not to have suffered any deterioration. Other similar reports 

 were mentioned. Dr. Young's allegation, that the oblique 

 braces were imitated from the French, is, according to Mr. Sep- 

 pin-^, inaccurate. The French had indeed introduced some pieces 

 of oblique tiinber, and they were to be seen in a ship which we took 

 from them ; but they had not been attended with any benefit, and 

 were abandoned as useless by the French themselves. Mr. Sep- 

 pings's mode is quite new, and the benefit of it sufficiently obvious. 

 On Thursday, the 4th of May, a paper by Sir Humphry Davy 

 was read, on the action of acids on hyper oxymuriate of potash. In 

 consequence of the discovery of a new acid by Gay-Lussac by 

 treating hyper-oxymuriate of barytes with sulphur. Sir H. Davy was 

 induced to examine more carefully than had hitherto been done the 

 action of acids on the hyper-oxymuriate of potash. When sulphuric 

 acid is poured upon this salt in a wine-glass, very little elfervescence 

 takes place, but the acid gradually acquires an orange colour, and 

 a dense yellow vapour of a peculiar and not disagreeable smell floats 

 on the surface, 'i'hcse phenomena led the author io believe that 

 the substance extricated from the salt is held in solution by the acid. 

 After various unsuccessful attempts to obtain this substance in a 

 separate state, he at last succeeded by the iollowing method. About 

 GO grains of the salt are triturated with a little suljihuric acid, just 

 sufficient to convert them into a very solid paste. This is put into a 

 retort, which is heated by means of hot water. 'Jhe water must 

 never be allowed to become boiling hot, for fear of explosion. 

 The heat drives olf the new gas, which may be received over mer- 

 cury. This new gas has a much more intense colour than euchlo- 

 rine. It does not act on mercury. Water absorbs more of it than 

 of cuchlorine. Its taste is astringent. It destroys vegetable blues 

 without reddening. When phosphorus is intniduced into it, an 

 explosion takes place. When heat is applied, the gas explodes with 

 more violence, and producing more light, than euclilorine. When 

 thus exploded, two measures of it arc converted into nearly i luce mea- 

 sures, which consist of a mixture of one measure chlorine and two 

 measures oxvgcn. Hence it is composed of one atom chloi ine and four 

 atoms oxygen. It is not unlikely that cuchlorine is a simjile n)ixturc 

 of three measures of chlorine and two measures of this new gas ; but 

 the point cannot be determined till it be known whether Dutch foil 

 will burn in sucli a mixture as it docs in euclilorine. 'I'his experi- 

 ment the author could not try, because at Home, where he then 

 was, he could proi ure no Dutcli foil fit for Ills pui j)Ose. The same 

 gas is disengaged from hyper-oxymuriate of jxitash by nitric acid, 

 and with still greater facility ; but it is alvvayu mixed with one-fifth wf 



