"If the density of the one (chemical element) is not so much greater than that of the other as to overcome the attraction of its parts, the aether in each upon their approach will repel each other. If the density is greater, they will be attracted and join each other." Cullen
"Every body is surrounded by its own proper atmosphere of this fluid (ether), which grows more dense as it recedes from the surface. This is analogous to the atmosphere of excited Electricity which determines bodies once got within the sphere of its attraction to the surface of the electric body. It is to be observed, that bodies thus in contact with the excited body, remain, some longer, some a shorter time in contact with that body, until they have got an atmosphere of their own: then they are propelled till meeting with some other matter, they discharge their atmosphere, and are attracted and repelled as before." Cullen