C l 4 l ] 
From this Confideration it will be eafy to account 
for a famous Experiment of the late Mr. Hawksbee , 
which is this 
Having pumped out all the Air from a Glafs Globe, 
he caufed it to turn on its Axis very fwiftly, by 
means of a Rope with a Wheel and Pully then rub- 
bing the Glafs with his Hand during its Motion, there 
appeared a great deal of 'Light of a purple Colour 
within the Globe, without any Light or Attraction 
obferved on the Outfide of the Glafs, which is ob- 
ferved when the Air has not been pumped our. 
Then turning the Cock fo as to readmit the Air 
gently into the Globe during its Motion, the Light 
was broken and interrupted, diminifhing gradually, 
till at lafi it appeared only on the Outfide of the Glafs, 
where it was accompanied with Attraction. Does it 
not appear to be, that at firft the external Air by its 
Refinance drives back the Electric Effluvia , which go 
then to the Infide of the Globe, where there is the 
leaf! Refiftance ? For we obferve, that as the Air 
comes in, it repels the Electric Effluvia , that go 
inwards no longer, when all the Air is come in. If 
the Fad be lb, as the Experiment fhews, is not my 
Conjecture proved, viz. that the Air is Electrical? 
In the Reverend and Learned Dr . Haless Vegetable 
Statics , feveral of his Experiments fhew, that Air is 
abfotbed, and lofes its Elafticity by the Mixture of 
fulphureous Vapours, fo that Four Quarts of Air in a 
Glafs Vefiel will be reduced to Three. Will not this 
Ehtcnomenon be explained by the different Electri- 
city of Sulphur and Air ? The Effluvia ol Sulphur, 
being electric, repel one another; and the Particles 
of Air, being alfo electric, do likewife repel each 
T 2 other. 
