88 



NATURE 



\_Nov. 29. 1877 



small funnel i, which may be raised or lowered at pleasure 

 by means of its support. Pour into I a certain quantity 

 of alcohol coloured say with a red solution of aniline. 

 The liquid will traverse the capillary tube, from which it 

 will flow unless prevented by compressing the india-rubber 

 tube with a small pincers. This being done, fill with 

 water the vessel C about three-fourths full ; then by means 

 of a funnel whose lower extremity reaches a little below 

 the middle of the water, introduce a liquid denser than 

 water, a concentrated solution of sea-salt or a thick syrup, 

 until the vessel is filled up. Sulphuric acid may also be 

 used, and in that case a less volume of liquid will suffice. 



Flc. «.— Experiments of Prof. Martini on the diffusion of coloured liquids in a 

 sirupy liquid. 



The liquid more dense than water will collect at the bottom 

 of c ; and there will thus be two layers of liquid superposed, 

 the exact separation of which may be observed after being 

 allowed to stand for an hour. If at the end of that time 

 we raise the funnel i to a suitable height and relieve the 

 pincers which compress the tube a b, the coloured alcohol 

 which flows from the extremity of the capillary tube will 

 enter the liquid in the vessel c, forming an ascending vein 

 which usually has a spiral form. The alcoholic vein 

 traverses the thickest layers of the liquid and is stopped 

 at the boundary which separates Uie denser from the less 



dense part which floats above. At the point where the 

 column of coloured alcohol is arrested, it will be seen to 

 agglomerate into a mass at first formless ; but, gradually, 

 that mass elongates and extends, then is seen to throw 

 out fluid threads in the form of foliage, sometimes similar 

 to the petals of a flo-ver, sometimes analogoas to the 

 leaves of a tree. A'ter an hour the coloured alcohol has 

 assumed a stable and regular figure. That figure varies 

 in form with the liquids employed ; it sometimes resembles 

 a flower, sometimes a shrub, and sometimes it takes the 

 form of a parasol of bright and vaporous coluurs, which 

 add to its beauty. 



The figure, so far as its form is concerned, 

 attains its maximum of developraeat three hours 

 or more after the fluid vein begins to flow ; but 

 after that time the leafy expansions dilate more 

 and more, and approach each other so as to 

 form a mass of con'inuous layers, which remain 

 suspended in the midst of the liquid. This hap- 

 pens even when the inflow has been arrested, 

 either by applying the pincers to the india-rubber 

 tube, or even by lowering suitably the funnel, I. 

 It should also be remarked that around the vein 

 of ascending liquid there very often forms a very 

 fine tube, which assumes the aspect of the stalk 

 of the flower, or rather the trunk of the liquid 

 shrub ; from different points of that stalk ex- 

 pansions in the form of leaves will be seen to 

 proceed. 



In order that the experiments I have devised 

 may be successful, the tube through which the 

 coloured liquid enters the vessel ought to be 

 capillary, the flow ought to be gentle, and the 

 apparatus maintained in a state of complete rest. 

 It is necessary, moreover, to be careful first to 

 expel the air from the india-rubber tube, since 

 air-bubbles disturb the formation of the pheno- 

 menon. The following is a succinct resume of 

 some of the results I have obtained with different 

 liquids : — 



Colours of Aniline Solution. — -I made use of 

 aniline red, brown, green, and violet, dissolved in 

 alcohol, being careful that the solution was not 

 too concentrated. The forms obtained in sugared, 

 salted, and acidulated water, are those represented 

 in Fig. 2, Nos. i and 2. The figures obtained 

 resemble, as will be seen, leaf-like expansions ; 

 the ramifications are turned downwards in sugared 

 water (No. i) ; in salt water, on the contrary, 

 they are always raised, and at the commencement 

 even more so than is shown in the figure. When 

 acidulated water is used, the aniline colours are 

 modified by the action of sulphuric acid ; the 

 green becomes pale yellow, the red becomes 

 brown, and the violet acquires a beautiful green 

 colour ; but in all cases the shrub-like figure No. 2 

 is formed with perfect regularity. 



Litmus. Aqueous Solution. — With this solu- 

 tion we obtain in acidulated water the figure 

 represented in No. 3 (Fig. 2), which resembles a 

 small parasol. Looked at from above, it has 

 the aspect of a disc from the periphery of which 

 proceed many equidistant rays very close to 

 each other. In the salt water the same aqueous solution 

 gives a different figure. In general, when aqueous solu- 

 tions are employed to form the figures a space of time is 

 required longer than that which is necessary in the case 

 of alcoholic solutions. 



Alcoholic Solution. — With this solution there are formed 

 in salt or sugared water, figures analogous to Nos. i and 

 2 ; in acidulated water there is produced a shrubby 

 appearance similar to No. 2. 



Lake. — The aqueous solution of lake forms in salt 

 water a figure similar to that of No. 4 ; in acidulated 



