31

Of the AttraEtion of Cohesion.

ture of the Earth by the Fibres of theRoots : Also for the Rife of the Sap in Ve-getables, and for the whole Oeconomy ofVegetation in general. Hence the Ratio-nale of the various Secretions of Fluids bythe Glands of an Animal Body, and theirwonderful Circulation through the fine Ca-pillary Vessels. Hence also the Reason ofSoldering and Gilding of Metals; also ofMelting or Fusion of Heat. Hence alsothe Exhalation of Vapours by the Heat ofthe Sun or Fire; the Aggregation of Aque-ous Particles in the Air, forming the Dropsof Rain. We hence fee the Reason of

Dijiil-

j»Ethw by Cohesion, till the Gravity of the Whole drawsit from the Part to which it coheres. Without this Co-hesion there could be formed no Drop at all.

24. Hence likewise it is, that a Column of Mercurywell purged of Air, will be suspended by Cohesion tothe Height of 70 or 75 Inches, when the Air alone willsustain it to no greater Altitude than that of 31 Inchesat most. Dr. ‘Jurin supposes the Pressure of an elasticsubtle Medium (which can penetrate the Pores of Glassand Water) to have some Part in producing this veryodd Phænomenon. But if all we can learn from Ex-perience be thought insufficient, I shall leave theReaderto amuse himself with what Conjecture he shall thinkfitj assuring him in the last Place, that this wonderfulSuspension of the Fluid in ever so large a Glass, as A C,whose Top terminates in the Capillary B, is not owingto the Pressure of the Air, because,the same Thing willhappen in an exhausted Receiver on the Air-Pump. See Plate I.Appendix, Numb. II. to Cote’s Le£lures. Fig. 19.