1 9971 
lowable to endeavour a rational accountof the feveral 
Phenomena of a portion of matter from fome known pro- 
perty of that body which it makes up or whichadls upon 
it, tho' there cannot prefcntly be given a Mechanical ac- 
count ofthat property its felfe. Thus all the appearan- 
ces, which were formerly refolv*d into zMetus Vacui^ 
afdHow accounted for by the weight and Ipring of the 
Air, tho' the Air s weight and fpring be not refolv d into 
their tfue Meehanifm. And in this all I aim at is to offer 
the irioft natural and rational method for refolving die 
ordinary changes of the weather, and to, make appear' 
that 'tis more eafie and intelligible to account for the fal- 
ling of rain and the impetuofity of Winds by the change 
of theAtmolphere's gravity,then to explicate the change 
of the Airs weight from the rain and Winds. 
But n6w as to the thing its felf, there can hardly be 
expected a fatisfadory account till we come to know the 
caufe of gravity in general, and of die Airs weight in 
{^articular; and therefore I fliall only here offer 2 or 3 
hints which perhaps may incite others to confider it more 
narrowly and i. it is now almoft generally acknowledged 
that there muft needs be a fluid much more fubtil then 
common Air and of a far greater prefTure then Air which 
is the caufe of the continuity and cohefion of all terref- 
trial bodys, and in which the Air feems as it were to float 
and to have the fame relation to it, as the Vapours do ia 
and have to the Air, and therefore if we could reach its 
nature and properties it might be confidered what infiu- - 
ence this may have upon the change of the Air's gravity. 
Or 2. Seeing the Infufion of one Liquor into another ia . 
Chymical preparations will alter its fpecifical gravity fo 
that the bodys which were formerly born up in it, will , 
fall down and be precipitated ("as the particles of Gold 
floating through Aqua %egts will be precipitated by the 
infufion of another Chymical Liquor, ) it may be confi- 
dered whether plenty of Nitrous Steams or fome fuch 
mixture.: 
