CAPILLARY ATTRACTION. 



407 



Ury The great discrepancy between these reiults, which 

 to more than a half of the whole altitude, 

 """" is a most satisfactory proof of the total insufficiency 

 of the method of measurement which was employed. 

 rV.r/. r>. If the preceding experiment is tried with 

 fluids of different kinds, it will be found that they 

 rise to different altitudes. Messrs Hauy and Tremery 

 found, that oil of oranges rose 6.74 thousandths of 

 a metre, in a tube whose diameter was one thousandth 

 of a metre, which reduced to a tube -j- 7 of an inch in 

 diameter, gives only 1.0447 inch, or 0.010447 for the 

 constant quantity. Mr Benjamin Martin made a va- 

 riety of experiments on different fluids, with a tube 

 -,'r f an > nca i diameter, and obtained the following 

 results. 



Altitude of 

 the Fluids. 



Constant 

 Product. 



Common spring Water 1.2 .04-8 



Spirit of Wine . hi .044 



Tincture of Galls 1.1 .044 



Recent Urine 1.1 .044- 



Vinegar 0.95 .038 



Spirit of Salt- 0.9 .036 



Ol. Tart, per deliq 0.9 .036 



Small Beer 0.9 .036 



Strong Spirit of Nitre 0.85 .034 



Spirit of Hartshorn 0.85 .034 



Cream 0.8 .032 



Skimmed Milk 0.8 .032 



Aquafortis 0.75 .030 



Red Wine 0.75 .036 



White Wine 0.75 .036 



Ale 0.75 .030 



Ol. Sul. per Campan 0.65 .026 



Sulphuric Acid 0.65 .026 



Sweet Oil 0.6 .024 



Oil of Turpentine 0.55 .022 



Geneva 0.55 .022 



Rum 0.5 .020 



Brandy 0.5 .020 



White hard Varnish 0.5 .020 



Spirit of Wine 0.45 .018 



Tincture of Mars 0.45 .018 



Exp. 6. If tubes of different lengths are employ- 

 ed, the fluid will never ascend to the top of the tube, 

 however short. Thus in Fig. 5. if the tube AC is 

 broken off at P, the fluid will stand at p below the 

 top P, though it formerly rose as high as A. We 

 have tried this experiment repeatedly with a tube 

 0.36 of an inch long, and 0.043 in diameter, and 

 have found that the fluid always rises to the very top 

 of the tube. 



Esp. 7. If a capillary tube, composed of two cy. 

 linders of different bores, be immersed in a fluid 

 first with the widest part downwards, as at E, Fig. 5. 

 and afterwards with the narrowest part downwards, 

 as at F, Fig 6. the fluid will ascend in both cases to 

 the same height. 



Exp. 8. W r hen the widest part of the tube is not 

 capillary, but is of such a magnitude that the fluid 

 will not rise spontaneously to the smaller part, let the 

 wider part be filled by suction, and the fluid will stand 

 at the same height in the smaller part of the tube, as 

 it would have done had the whole tube been of the 

 Mime bore with the capillary part, 



'. 9. If the tube, when filled by auction, at in the Capillary 

 preceding experiment, is placed in the receiver of an Attraction. 

 air pump, and the air exhausted, the fluid in the wider ~*^ * ~ 

 part of the tube will not remain impended in the 

 tube as formerly, but will fall down into the vesteL 



Exp. 10. If one tube is placed within another K> 

 that their axes coincide, the water will rur in the 

 space between the tubes only to half the height that 

 it would have done in a single tube, in which the di- 

 ameter of the bore is equal to the interval between 

 the two tubes. 



Exp. 1 1 . When the internal diameter of several ca- 

 pillary tubes are equal, the fluid will rise to the tame 

 height whether the tubes are thin or thick. 



Exp. 12. Having plunged a capillary tube into wa- 

 ter, let the lower extremity of it be closed with the 

 finger, and when the tube is taken out of the water, 

 let its external surface be gently wiped. Upon with- 

 drawing the finger, the water is seen to subside in 

 the tube and form a drop at its lower base ; but the 

 height of the column is always greater than the ele- 

 vation of the water in the tube, in the common ex- 

 periment of plunging it in water. It has also been 

 observed, that the increase in the elevation of the wa- 

 ter is more considerable, the smaller the diameter of 

 the drop beneath. 



Exp. 13. If a drop of water is introduced into a 

 conical capillary tube, open at both ends, and held in 

 a horizontal position, it will move towards the vertex 

 of the cone. 



Exp. 14. When water is forced through a capillary 

 tube, of such a bore that it is discharged only in suc- 

 cessive drops, it will flow in a constant and accelera- 

 ted stream when the tube is electrified, and the acce- 

 leration will be inversely proportional to the diame- 

 ter of the bore. This fact seems to be denied by 

 Carmoy. See Journ. de Physique^- xlv. 106. 



Exp. 15. A capillary syphon which discharges 

 coH water only by drops, will discharge water of a 

 higher temperature in a continued stream. . 



Exp, 16. Let a capillary tube be held in a position 

 inclined to the horizon, and let a drop of liquid be 

 let fall upon its surface, then bringing the tube into 

 a vertical position at the instant when the drop has 

 arrived at the inferior orifice, the fluid will run 

 through the orifice, and rise in the interior of the 

 tube. 



Exp. 17- If the preceding experiments with capil- 

 lary tubes, excepting Exp. 9, be made in the exhaust- 

 ed receiver of an air pump, the fluids will rise to the 

 same height as in the open air. 



Exp. 18. If the bore of a capillary tube be lined 

 with a very thin coating of grease, or any unctuous 

 substance, the water will not ascend in the tube. 



Exp. 19. By observing carefully the upper surface Form of the 

 of the column of fluid, elevated in capillary tubes, it surface of 

 will be found to be concave upwards. M. Hauy 

 found, that in capillary tubes of glass, of very small 

 diameters, the concave surfaces of water and of oils 

 differ very little from the form of a hemisphere. 



Exp. 20. If the capillary tube is taken out of the 

 fluid in which it is immersed, and inclined to the ho- 

 rizon so that the included fluid may obey the action 

 of gravity, the concavity will appear at both ends of 

 the column, and suffers no variation either in its shape 

 or size, whether the tube be held in a vertical, a he 

 rizcnul, or au oblique direction. 



* m 



