Knowledge. 



With which is incorporated Hardwicke's Science Gossip, and the Illustrated Scientific News. 



A Monthly Record of Science. 



Conducted by Wilfred Mark Webb, F.L.S., and E. S. Grew, M.A. 



APRIL, 1913. 



EXPERIMENTS ON LIQUID DROPS, GLOBULES, 



AND COLUMNS. 



By CHAS. R. DARLING, A.R.C.Sc.I., F.I.C. 



II. 

 LIQUID COLUMNS. 



If a large drop of liquid be formed in a shallow 

 layer of water (after the manner described in the 

 previous article), so that the drop reaches the bottom 

 of the vessel before parting, it will generallv spread 

 so as to take the shape of the 

 lower portion of the vessel ; and 

 if the upper part of the drop be 

 brought to the surface of the 

 water, and the delivery tube be 

 detached, a column of the liquid 

 may form. In practice, however, 

 it is not easy to obtain a liquid 

 column in this manner ; but by 

 carrying out the following instruc- 

 tions the formation may be 

 secured with ease and certainty: — 

 Take a test-tube 2-5-cms. (1-in.) 

 or more in diameter, and nearly 

 fill the hemispherical end with 

 water. Incline the tube, and pour 

 uceto-acetic ether very gently down the side, until the 

 level of the liquids rises about one centimetre in the 

 cylindrical part. On erecting the tube, a column, 

 similar to that shown in Figure 116, will he formed, 

 the upper part being attached to the surface of the 

 water, whilst the lower end rests on the test-tube. 

 The curved sides of the column will be seen to 

 possess a most graceful outline, and are bounded by 

 water. The shape of the column thus formed may 



UGL 



A column of aceto- 



be varied by employing a wider tube, in which case 

 the column will be relatively narrower at the top ; or 

 by gradual additions of water, which stretch the 

 column longitudinally, causing the diameter at the 

 middle to diminish until breakage 

 occurs. The change produced by- 

 adding successive small quantities 

 of water is shown in Figures 

 117-120, which represent four 

 stages in the stretching of a 

 column of Iso-butyl benzoate. 

 The varied outlines of the columns 

 are extremely pleasing, and the 

 last picture of the series shows 

 the width at the moment of 

 breakage, which in this case 

 occurred during exposure, the 

 column appearing in faint outline. 

 After severance, the greater portion 

 sinks to the bottom of the tube, 

 the remainder hanging from the surface in the form 

 of a globule. It may be added that the water should 

 be allowed to trickle down the side of the tube, 

 as, if dropped directly on to the column, water- 

 bubbles are formed which impair the shape. 



It might he expected that any liquid slightly 

 denser than water would, if insoluble, form columns 

 in the manner described. This is not the case, how- 

 ever, for reasons which at present cannot be entirely 



K li 1 1 f). 



acetic ether in water. 



121 



