VOL. XXVII.] PHILOSOPHICAL TRANSACTIONS. GSQ 



bottom of the sea, so as to let the water in to extinguish it; I am of opinion, 

 that it may yet last longer than they imagine ; and that this phenomenon will 

 continue, till the mine of sulphur is entirely consumed. 



^n Account of many Rare Plants, lately observed in several curious Gardens 

 about London, and particularly the Company of Apothecaries Physic Garden 

 at Chelsea. By Mr. James Petiver, F.R. S. N° 332, p. 375. 



An Experiment, showing the Direction of a Drop of Oil of Oranges, between 

 two Glass Planes, towards any Side of them that is nearest pressed together. 

 By Mr. Fr. Hauksbee, F.R.S. N° 332, p. 395. 



The glass planes used were about 6 inches square ; and being very clean, a 

 drop or two of oil of oranges was let fall on the lower plane, suppose at b, 

 fig. 3, pi. 17; then the upper plane was laid on it; so near as to touch the 

 liquid, that it might become contiguous to both their surfaces. Thus the 

 planes being made to touch one another at the side a, and opened at the side 

 c, as in the figure, the lower plane lying parallel with the horizon, the drop 

 of oil would immediately move towards the touching side of the planes; and 

 when it was arrived there, it was but reversing the angle, and the drop would 

 return from a to c ; and after the same manner it might be directed to any side 

 or part of the same. And, if the planes were elevated 8 or 10 degrees at a, 

 yet would the drop ascend towards the side a, though not so swift as when the 

 planes were in the forementioned position. It was further observed, that the 

 nearer the drop approached the touching side, so would the velocity of its 

 motion be increased: the reason of which seems very plain, allowing the ascent 

 of water in small tubes, and between the surfaces of nearly contiguous planes, 

 to be explained from the power of attraction, that one surface has to another 

 at such a nearness. For the drop of oil moving on towards the contiguous 

 surfaces, comes to enlarge its space, and touches the planes in more and more 

 parts, as it approaches nearer and nearer the touching side. Thus in the whole 

 progress of its motion, it is continually increasing in its surface, and conse- 

 quently the power of attraction must increase in proportion to that surface ; so 

 that the celerity of its motion must necessarily be augmented. This experiment 

 seems very powerfully to confirm the experiments made before on the same 

 subject, from the gradual increase of the motion of the drop; thus represent- 

 ing the several appearances of the ascent of water in different sized tubes, or 

 between planes whose surfaces are placed at different distances, the slower 

 motion representing those experiments made in larger, and the swifter in 



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