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The explosion of aurum fulminans is more vehementthan that of any other known kind of matter : it goes offin a less degree of heat than any of the other explosivecompositions ; and even grinding it somewhat smartly ina mortar is sufficient for making it explode. Some instan-ces are mentioned in the Breslau collections, and theephemerides. yiaturce curioforutn , of a very small quantitybursting in pieces the marble mortar in which it wasrubbed; and an accident of the same kind happened someyears ago to a skilful chemist here. The operator cannotbe too much on his guard in- the management of so dan-gerous a preparation. ^

It has been reckoned, that a few grains of aurum ful-minans act with as much force as several ounces of gun-powder r but the actions of the two are of so differentkinds, that I cannot apprehend in what manner theirstrength can be compared. The report of aurum fulminansis of extreme acutenefs, offending the ear far more than:that of a much larger quantity of gunpowder, but doesnot extend to so great a distance ; seeming to differ fromit as the found of a short or tense musical' string from that.of a long one or of one which is less stretched. In someexperiments made before the royal society and mentionedin the first volume of Dr. Birch’s history, aurum fulminansclosed up in a strong hollow iron ball and heated in thefire, did not appear to explode at all; while gunpowdertreated in the same manner burst the ball. On the otherhand a little aurum fulminans, exploded on a metallineplate in the open air, makes an impression or perforation:in the plate ; an effect which gunpowder could scarcely,produce in any quantity.

This remarkable effect of aurum fulminans on the bodywhich serves for its support, has induced some to believethat its action, is exerted chiefly or solely downwards*.

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