2 7

Of the AttraEHon of Cohesion.

of any elaflic Quality ; which all arise fromthe different Figure of the Particles, and

the

tion of Mirrours may be improved by this Method,must be left to farther and future Experience : And alsowhether it be not practicable by this Means to make avery large and most effectual Burning-Glass, at a veryeasy and cheap Rate.

14. A late French Author (L’Abbe Nollet) has thoughtfit to call in question the Cause we have here assigned forthe Rife of Fluids in Capillary Tubes, and has almostsneered "Dr.fterm's learned Diflertationson that Subject}but I fee nothing that could oblige him to do this, fromwhat he has said to explode it; no Man can be con-vinced by his ipse dixit, that this is a mere Hypothesis ;the Phesnomena so plainly indicate the Cause to be At-traction, and agree in every Particular so nicely to theTheory, that ’tis not to be expected we should give itup till we see better Reason for it than this reverend Fa-ther has given in his prolix Digression on this Subject.See his Lepons de Physique Experimentale, Tom. II.Page 421, tsfe.

15. But though the Attraction of the Glass is the in-dubitable Cause of the Ascent of Fluids, yet it mustbe allowed that the Nature and Genius of the Fluid is tobe regarded in most of the Phœnomena, which are notproportioned to the attracting Power of the Glass only,but to that Power conjointly with the various Dispositionof Fluids to yield thereto; nor is the Density of theFluid of primary Consideration, it being evident by Ex-periment, that some lighter Fluids will rife to a lessHeight than others which are much heavier : Thus Spi~rit of Wine will rife but 4! Tenths of an Inch in aTube, where Oil of Tartar will rife 9, as in the Fablebelow. Nor does it at all depend on the Viscidity orTenacity of Parts; for hard white Varnish (very thickand viscid) and Spirit of Wine ascend nearly to thesame Height. I am inclined to think from the Experiments which I have made, that the Ascent of Fluids

depend