18 



Vince. The depression of the horizon, frequently noticed by persons 

 residing near the sea, and some other phsenomena of a similar nature, 

 he thinks may likewise be ascribed to that single cause. 



On a new fulminating Mercury. By Edward Howard, Esq. F.R.S. 

 Read March 13, 1800. {Phil. Trans. 1800, p. 204.] 



We learn from the introduction to this paper, that mercury, and 

 most, if not all, its oxides, may, by treatment with nitric acid and 

 alcohol, be converted into a crystallized compound, possessing all the 

 inflammable properties of gunpowder, as well as many others peculiar 

 to itself. After stating the gradual steps by which he arrived at this 

 discovery, Mr. Howard describes the following process and manipu- 

 lations, which he found best calculated for producing this powder. 



One hundred grains, or a greater proportional quantity, of quick- 

 silver, are to be dissolved with heat in a measured ounce and a half 

 of nitric acid. This solution being poured cold upon two measured 

 ounces of alcohol, a moderate heat is to be applied, until an effer- 

 vescence is excited. A white fume then begins to undulate on the 

 surface of the liquor, and the powder will be gradually precipitated 

 upon the cessation of action and re-action. This precipitate is to be 

 immediately collected on a filter, well washed with distilled water, 

 and carefully dried in a heat not much exceeding that of a water- 

 bath. This immediate edulcoration of the powder is material, it 

 being liable to the re-action of "the nitric acid, which, while any of 

 that acid adheres to it, renders it subject to the influence of light. 

 The quantity of the powder produced varies according to the nature 

 of the ingredients ; 100 grains of quicksilver yielding from 120 to 

 132 grains of the compound. 



The principal agents which decompose this mercurial powder are 

 the nitric, the sulphuric, and the muriatic acids. The most remarkable 

 effect is that of the sulphuric acid, which, when much concentrated, 

 produces an explosion nearly at the instant of contact, on account, it 

 is thought, of the sudden and copious disengagement of the caloric. 

 When the acid is less concentrated, no explosion takes place ; but a 

 considerable discharge of gas, as well as caloric, is nevertheless ef- 

 fected ; the former appearing to be a compound of carbonic acid and 

 a peculiar inflammable gas, amounting in the whole to between 28 

 and 31 cubical inches. The inflammable gas was upon close exami- 

 nation found to be a nitrous setherized gas, which appears to have 

 been not the result of the decomposition, but, in fact, a constituent 

 part of the powder. 



Upon the whole of the investigation, Mr. Howard concludes that 

 this mercurial powder is composed of nitrous aetherized gas, and of 

 oxalate of mercury with excess of oxygen. Having stated his reasons 

 for maintaining this opinion, he goes on to explain the theory of the 

 combustion of the mercurial powder, on certain principles previously 

 laid down in the investigation. The hydrogen, he says, of the oxalic 

 acid and of the aetherized gas is first united to the oxygen of the 



