not only to _push_ the air from place to place, but also to _break it_ so small, as to be in form of _light_: which he shews us by his third, fourth, and fifth experiments to be the case; for by these experiments he produced _light_ in an _unexhausted_ receiver; but then the _motion_ or _agitation_ was required to be much _greater_ than that which produced _light_ in _vacuo_. The difference of these two _lights was very considerable_, and consisted particularly in this, that the luminous particles are _distinct_ and _separate_ in the experiment performed in the _open air_; and _united_ and _blended_ into one continued body of _light_, in the other experiments in _vacuo_; which difference proves to a demonstration, that the exhausted receiver was full of nothing but _light_; for, on shaking the mercury therein, the whole body of the receiver seemed to be _one continued body of light_; but on shaking the mercury with ever so great a violence in the common air, it seemed full only of _little_, _bright_, _twinkling sparks_; and not one continued body, as in _vacuo_. For, as the appearance of _light_ is produced in the common air, by the _friction_ of the mercury against the glass receiver, _breaking_ or _grinding_ the air to pieces (which small particles put on the form of _light_) so, when the common air _presses_ in between these small particles, the appearance must be, and cannot be otherwise than is shewn by these experiments. These many and various experiments abundantly prove, that _light_ is produced as above described; and not, as the generality of people have imagined (from that mistaken notion of _action_ being performed by _solids_ and not by _fluids_) that this electrical _light_ proceeded from the glass globe, emitting, what they call, _electrical effluvia_, which has been shewn before to be impossible; because if any quantity of matter sends off part of its own body, there must be less of that body remaining, than before the above matter was sent off, which we find is not the case of the glass globe; and to prove that it does not, I shall bring one experiment more from Mr. _Hauksbee_ which will put it beyond doubt. Pag. 27. he shews us, that by a violent _attrition_ of _woollen_ against _woollen_ in _vacuo_, he produced _light_, as well as from any _hard_ or _electrical_ body; but not so vivid, nor in so large a quantity. Now, as woollen is reckoned by all to be a _non-electrical_ body, it shews us that the _light_ must proceed from the _attrition_ of the air, and not from the _electrical body_, as has been falsely imagined.