I put thirteen Grains of this last fix’d Powder (VIII.) into a Crucible, and set it over an open Fire before the Bellows: I increas’d the Heat of the Fire, by blowing till the whole Crucible was red hot: I kept it so for a Quarter of an Hour. The Powder remain’d fix’d in the Bottom, but swell’d up like a Spunge, and of a dark Colour. From hence I learn’d that this Powder had acquired a considerable Degree of Fixedness by Fire alone.