and its relation to Latent Heat. 5 



§ 6. The quotient Q may be computed from the product of 

 the diameter of a tube by the mean elevation of the capillary 

 column, which in theoretical works on capillary attraction is 

 assumed to be constant for the same liquid at constant tempera- 

 ture. Supposing the tube to be drawn up one inch, the capil- 

 lary column descends one inch, denuding !'"• x 7rf? of surface, and 

 the work jicrformed is the vokuue ^d^Trh descending one inch : 



we have therefore .jr// 4 



0=— — — = — 

 ^ ^irdVi d/i' 



in w^hich d is diameter of tube, and /* the equalized height of the 



suspended column. The value of dh, computed from Q=133 



[§ 2], is 5^ = 0-0303, which agrees nearly with Dr. Brewster's 



value given in Table, p. 279, of the Report of the British Associa- 

 tion, 1834. In small tubes, where the abnormal tendency [§ 8] is 



2 

 manifested, the value of Q is about ^ of 132 or 88, and the cor- 

 responding value of dh is 0*045, which agrees nearly with that 

 given opposite the names Martin and Morveau in the same Table. 



By similar reasoning, in the case of plates we have Q = jy^, in 



which D is the distance of the parallel plates, and H the equal- 

 ized height of the capillary column. 



§ 7. The 32nd volume of the Amides de Cltimie (1851) con- 

 tains an extensive series of researches on capillarity by M. Simon. 

 Water was the liquid chiefly employed, and the dimensions of 

 the capillary column in tubes of different bores, and between 

 plates at different distances, were measm-ed with great minute- 

 ness. The most remarkable result of these observations was the 

 discovery of the fact, that the column between plates is only about 

 one-third tlie height of the column in tubes, instead of one-half, 

 as theory liad previously indicated. If we assumed this as a general 

 law, and employed the Table of specific capillarities given in p. 15 

 for computing the values of Q for alcohol, aether, and carburet of 

 sulphur, we should be led into serious error. The Table shows the 

 comparative heights of the capillary columns in fine tubes only. 

 Another table is required to show the comparative heights 

 between parallel plates, in which, setting out with the height of 

 water as unity, the numbers for carburet of sulphur, alcohol, and 



3 



sulphuric wthcr must be multiplied by ^. The tcmperatui-e at 



which the observations were made is not specified, which is an 

 omission of some consequence, seeing that there is jjroof that the 

 ratios of capillarity change with the temperature [§ 10]. 



§ 8. The existence and extent of this abnormal feature may 



