Mr. C. Tomlinson on the Cohesion- Fig ures of Liquids. 357 



fluid after having been thoroughly melted. Castor oil was used 

 at various temperatures, but some of the finest figures were ob- 

 tained on its surface at the ordinary temperature of the air of 

 the room. Fine figures were also obtained on the surface of 

 cold olive oil. Some of these figures are represented in Plate VI. 



Cocoa-nut Oil. — X drop of ether flattened into a very perfect 

 disk about two-eighths of an inch in diameter : this was sur- 

 rounded by a dentated ring, from which proceeded a multitude 

 of rays, as shown in PI. V. fig. 4. The best-defined figure was 

 obtained when the temperature of the surface was about 80°. 



Alcohol produced a disk about three-fourths of an inch in dia- 

 meter, with a small boss in the centre surrounded by a number 

 of concentric circles faintly tinted with iridescent colours, while 

 the edge of the disk was delicately fringed with very short radial 

 lines. The figure was first of the size shown in fig. 1, No. 1 ; 

 it then expanded to No. 2, and disappeared by closing in upon 

 its centre. The figure was quite sharp and distinct, giving the 

 idea of a lid of a box turned in the lathe. The best result was 

 obtained when the surface was at about 90°. 



Benzole gave a figure about 2 inches in diameter, consisting of 

 a central depressed disk about three-eighths of an inch in diameter, 

 with a slight conical projection in the centre and surrounded by 

 a broad smooth flat ring terminating in a sharply-cut edge. Oil 

 of turpentine gave a somewhat similar figure, only the outer 

 edge was wavy. Paraffin oil and Persian naphtha also give 

 figures of the same type. Oil of lavender gave a central disk, 

 from which issued wavy processes which were torn away by the 

 adhesion of the surface. 



Castor Oil. — When the oil is at about 94° F., a drop of ether 

 forms a large figure bounded by a well-defined circular edge, in 

 the centre of which figure is a plain disk surrounded by a narrow 

 plain line; just outside the disk is the engine-turned pattern, 

 and beyond this, as far as the boundary edge, the disk is quite 

 smooth. The engine-turned pattern seems to be produced by 

 the revolution, or rather oscillation, of the central disk on the 

 heated surface. On cold castor oil the ether figure consists of a 

 central boss surrounded by rippled waves, very much like the 

 rose-pattern of the turner. Fig. 3 represents these two figures. 



"When the oil is at 94°, a drop of alcohol forms a central star 

 in a large disk surrounded by iridescent rings. But a finer figure 

 is produced on cold castor oil : the drop spreads out into a large 

 disk with broad iridescent bands just within the sharp-cut edge ; 

 having attained a diameter of about 3 inches, it retreats towards 

 the centre, leaving a beautiful network of minute globules. A 

 drop of camphorated spirit produces a still finer figure, an idea 

 of the beauty of which can scarcely be conveyed in words. A 



