I. We are certain, that this electrical fire is produced, either from the glass globe, or the air that surrounds it. As to the glass globe, Mr. _Freke_ has fully proved it cannot proceed from that; “Because nothing, we know of, can send out of it a quantity of matter, but there must be less of that matter remaining, after it has been so discharged; whereas it cannot be shewn, but that the glass globe, after ever so many times using, remains as fit for the same use, as at first.” From hence we assert, that this fire must proceed from the surrounding air being acted upon by the glass globe; and our inquiry must be, how, and by what means, fire is produced by the glass globe being made to act upon the air by which inquiry we shall find, that _air_, _light_, and _fire_ are of the _same substance_, or _essence_; only differently modified, and appointed for performing different actions: that air (by being divided or broke to pieces) produces light; and, if that action is still encreased, it produces fire. Now as the greatest friction or attrition are necessary to produce fire, so fire, when it is once produced, having received the greatest force, of consequence _acts_ with the greatest force; and light, with a less; so, wherever there is the greatest quantity of these small particles of air, (which we call by the name of fire) in proportion to what we call gross air, there the action must be the greatest; by which means the said fire or light will expand itself, ’till, by mixing with what we call gross air, it becomes of an uniformity with it. Now therefore, as experiments are the sure way either of proving or disproving any _hypothesis_; so, to illustrate this, I shall produce some experiments both from Mr. _Freke_, and other authors of unblemished credit, which prove that air is convertible into light and fire, and also that light and fire are convertible back again into air; and likewise, as some parts of the air are present in all places and things, that therefore, whenever a violent action either of solids or fluids is brought on, there light, fire, or heat, are produced. To prove this, Mr. _Freke_ has brought, two very simple, common, but good experiments--First, if you slide a wax thread, or small rope, through your fingers, it will burn them; so likewise fire is produced, by rubbing two hard bodies together, or two sticks; or, as is very often the case, a cart or coach wheel will take fire, for want of grease.