6 ]Mr. J. J. Waterston on Capillar itij 



be ascertained with very simple appliances. I employed a tube 

 about 3 inches lonp: and -^\ih. of an inch diameter, marked with 

 diN-isions cut by a diamond-point at intervals of about y'T^th of an 

 inch, each line* being a guide to the eye, and the exact length of 

 a reading being ascertained by scale and lens. There were also 

 several thermometer-tubes with flat bore and scale engraved upon 

 them. The glass plates employed were kept separate and parallel 

 by inserting a piece of thin tinned plate, beaten flat and coated 

 with lac, between them when heated. One half of their surface 

 being thus cemented, the other half was left open for the capil- 

 lary column, and their perfect parallelism could be easily tested. 

 One of the plates was crossed with diamond lines as guides to 

 the eye in observing, and afterwards for applying the scale and 

 lens to obtain the exact reading. 

 The liquids employed were, — • 



Ist Class. 

 Distilled water. 

 Sulphuric acid. 

 Nitric acid. 

 Ammonia. 

 Saturated solution of common salt. 



2nd Class. 

 Alcohol. 



Sulphuric sether. 

 Sulphuret of carbon. 

 Dichloridc of sulphur. 

 Acetic acid. 

 Chloroform. 

 Acetic sether. 

 Acetone. 

 Turpentine. 



The ratios of the capillary columns of these sevei'al liquids in 

 the tubes and between the plates were compared, and it was 

 found that the columns of the first Ave liquids (being of the 

 nature of hydrous solutions) had a higher ratio to the others 

 when measured in the tubes than when measured between plates. 

 If the hydrous plate columns had changed in the same ratio as 

 the plate columns of the other liquids, their height in tubes of 

 small bore would have been about two-thirds the height observed. 

 Thxis if Q were estimated from the capillarity of water in small 

 tubes, the value is about two-thirds of 132 or 88 (Q being in- 

 versely as //, § 6). 



The measure of the tensile force at the surface of water and 

 hydrous liquids is thus not to be obtained from the apparent 



