*j% Dr. Young's Essay 
in Taylor's well known experiment the weight required was 
50 grains. But when the solid employed is small, the curva- 
ture of the horizontal section of the water, which is convex 
externally, will tend to counteract the vertical curvature, and 
to diminish the height of separation ; thus if a disc of an inch 
In diametex were employed, the curvature in this direction 
would perhaps be equivalent to the pressure of about one- 
hundredth of an inch, and might reduce the height from .2 to 
.about ,19, and the weight in the same proportion. There is 
however as great a diversity in the results of different experi- 
ments on the force required to elevate a solid from the surface 
of a fluid, as in those of the experiments in capillary tubes : 
and indeed the sources of error appear to be here more 
numerous. Mr. Achard found that a disc of glass, if inch 
French in diameter, required, at 69° of Fahrenheit, a weight of 
91 French grains to raise it from the surface of water ; this is 
only 37 English grains for each square inch ; at ^f a the force 
was J~ greater, or 39-J grains ; the difference being for 
each degree of Fahrenheit. It might be inferred from these 
experiments, that the height of ascent in a tube of a given 
bore, which varies in the duplicate ratio of the height of ad- 
hesion, is diminished about for every degree of Fahrenheit 
that the temperature is raised above 50* ; there was however 
probably some considerable source of error in Achard’s ex-* 
periments, for I find that this diminution does not exceed 
The experiments of Mr. Dutour make the quantity of water 
raised equal to 44,-1 grains for each square inch. Mr. Achard 
found the force of adhesion of sulfuric acid to glass, at 69° of 
Fahrenheit, 1.26, that of water being 1, hence the height 
Was as .69 to 1, and its square as .47 to i, which is the 
