TOL. XI.] PHILOSOPHICAL TRANSACTIONS. 366 



clear chemical oil, that was heavier than water, and whilst it was contiguous to 

 it, it had not a concave but a convex surface; and having placed the pipe 

 furnished with both liquors in the pneumatical receiver, we pumped out the air, 

 without finding that the oil sensibly altered its protuberant surface, as neither 

 did the water lose the concave figure of its upper surface. 



When clouds are condensed into rain, and lower aggregates of vapours into 

 dew, it is supposed to be obvious, that the drops of those meteors do, in their 

 passage through the air, acquire a round figure; and when we shake oil into 

 water, the portions of the former fluid, during the little time they remain 

 distinct, are found to be globular. But these phaenomena are too few, and too 

 transient, to afford any considerable observation of the figures of fluid bodies, 

 especially if they be quiescent, and every way encompassed by other fluids. 

 Wherefore I thought fit to try what I could do with chemical liquors unapt for 

 mingling, to produce phasnomena that may last long enough to allow us to ob- 

 serve them attentively, and in some cases to vary them. — For this purpose I 

 first took fixed nitre, or which is analogous to it, salt of tartar, resolved per 

 deliquium into a transparent liquor, and having filled a clear phial half full with 

 this, I poured on it a convenient quantity of vinous spirit exactly rectified, that 

 there might be no phlegm to occasion an union between the two liquors, which 

 ought, as ours did, to retain distinct surfaces, and speedily regain them though 

 the glass were well shaken. Then having found, by a trial formerly mentioned, 

 that common oil of turpentine, if employed in a competent quantity, will not 

 totally, and much less will readily, dissolve in spirit of wine ; and also having 

 observed, that if this spirit of wine be exquisitely dephlegmed, the oil though a 

 chemical one, will not swim on it, but sink in it; I warily let fall some drops of 

 the oil into the spirit, and had the pleasure to see that they fell towards the 

 bottom of the glass, till their descent was stopped by the horizontal surface of 

 the alcalizat liquor of fixed nitre. And because my design was chiefly to ob- 

 serve the superficial figure of a fluid encompassed by other fluids without touch- 

 ing any solid body, I shall here take notice of the chief phaenomena that were 

 produced of that kind, without staying to inquire into the causes or the con- 

 sequences of them. 



1. If the oily drops were but small, they seemed to the eye exactly enough 

 spherical. For the oil differing but little in specific gravity from the spirit of 

 wine, the drops did but just touch the surface of the subjacent alcali ; and the 

 same drops being but small, their own weight was not great enough visibly to 

 depress them, and prevent that roundness which the pressure of the ambient 

 spirit, or their own viscosity endeavoured to give them. — 2. If an aggregate of 

 drops were considerably larger than those newly mentioned, it would then 



