362 Mr. C. Tomlinson on the Cohesion-Figures of Liquids. 



arches. Balsam copaibsc (when the oil was at 165°) descended 

 in the form of a single thick glassy ring of perfect structure. 

 Some of the fixed oils formed pretty figures in a column at 110°. 

 Colza descended in the form of a cup with the edges turned over 

 and inwards, suspended by a line from the surface of the column 

 to the centre of the cup. Linseed oil also forms a hemispherical 

 cup with the edges turned over, but without the suspending line. 

 Sesame a similar figure/ only instead of the suspending line there 

 was an arched projection in the centre of the cup. Castor oil 

 sank rapidly in the form of a cup with the edges turned over 

 and inwards. Some of these figures are represented in Plate VI. 

 and are marked a, h, c, d, e. 



Castor Oil, Olive Oil. — A column of each of these oils is well 

 adapted for the exposition of sets of figures differing in many 

 particulars, but all distinguished by a bulb and a stem. Each 

 figure may be compared to a thermometer with a small bulb 

 and a long delicate stem. For example, when a drop of oil of 

 cloves is deposited on the surface of a column of cold castor oil, 

 6 or 7 inches in length, the greater portion sinks beneath the 

 surface (see No. 1), while the remaining portion forms a disk 

 on the surface, attached to the submerged globule by means of a 

 short neck (see No. 2). The weight of the globule drags upon 

 the disk and forms it into a conical cavity, containing a speck of 

 air, which, as the disk collapses by the weight of the descending 

 globule, becomes enclosed and is drawn out with a portion of the 

 oil of cloves into the form of a long narrow tube (No. 3) : the 

 disk at the surface, now reduced to the diameter of the tube, 

 remains attached to the surface, and, indeed, is so persistent in 

 its character that, long after the bulb has spread over the bot- 

 tom of the vessel, this tube or thread remains attached to its 

 moorings at the surface, and even interferes with the proper 

 development of a second figure in the same column if the latter 

 be narrow. As the tube is drawn out by the descending globule, 

 its material is supplied partly by the surface of the globule, and 

 partly by the medium, namely the castor or olive oil. The lat- 

 ter, in passing over the surface of the oil-of-cloves spheroid, 

 detaches a portion of its substance, and thus allows the tube 

 to increase in length. In the meanwhile the original drop of 

 oil of cloves, which near the surface was a sphere, flattens out 

 into the form of a spheroid ; and when it has descended about 

 one-third of the length of the column it appears to open, and the 

 apparent opening is ornamented on either side by the well-turned 

 volutes of an Ionic capital (see No. 4, and the figure further 

 developed in No. 5). This effect appears to be due to the pene- 

 tration of the spheroid at its lower surface by a portion of the 

 medium itself, which enters and diffuses within the spheroid in 



