CHEMICAL SCIENCE. 



plied th a principle involved to a species of chemical analysis. The 

 principle of the examination is to place a drop of a liquid on the sur- 

 face of clean water in a chemically clean glass, when a figure is pro- 

 duced which was characteristic of the liquid so tested, and capable of 

 being used for its identification. The figure formed is a function of 

 cohesion, adhesion, and diffusibility. If any one of these forces be 

 varied the figure varies. The figure of alcohol for example on water, 

 mercury, the fixed oils, melted lard, spermaceti, paraffin, sulphur, &c. 

 are all different. A new set of figures is produced by allowing the 

 drop to subside in a column of liquid instead of diffusing over its sur- 

 face. These last the author calls " submersion figures of liquids." 

 The figure of a drop of oil of lavender in a column of alcohol thus 

 produced is singularly complicated and beautiful. The test by cohe- 

 sion figures was stated by the author to be so delicate as to readily 

 distinguish differences between oils so closely related as the oleines of 

 beef-fat and mutton-fat, when the one was adulterated by the other. 

 Another series of results are obtained, not by placing a drop of the 

 liquid on the surface of water, but by allowing the drop to sink below 

 the surface before the figure is developed. In this way a large number 

 of figures of great variety and beauty have been produced by allow- 

 ing drops of various oils, solutions, and other liquids to subside in 

 columns of water, spirits of wine, ether, turpentine, paraffin oil, 

 benzol, and pyroligneous ether. For example, a solution of cochineal 

 (from 20 to oO grains in one fluid ounce of distilled water and fil- 

 tered) forms admirable figures, in a column of water contained in a 

 glass cylinder 11 inches high and three inches in diameter, into which 

 about A an ounce of solution of ammonia or a little alum water had 

 been poured. If river water be used the lime is thus thrown down, 

 so that the water should be allowed to stand a few hours before per- 

 forming the experiment ; or if distilled water be employed, the am- 

 monia and the alum, by their chemical action on the cochineal, add 

 to the beauty of the result. As soon as the drop of cochineal solu- 

 tion (delivered gently from a pipette) falls beneath the surface, it ex- 

 pands into a ring, sinks a short distance further, and then becomes 

 poised. The more diffusive portions of the coloring matter stream 

 upwards in a faint flame-like circular cloud ; the denser portions ac- 

 cumulate at two opposite points of the ring, which is thus at its thinner 

 portions bent upwards, and then drawn downwards into graceful fes- 

 tooned lines by the heavier portions, which form separate rings smaller 

 than the parent ring. These rings in like manner, descend. The 

 denser portions of coloring matter accumulate at the two opposite 

 points, 90 from the points of attachment to the festooned lines. 

 Each small ring is, in this case, also bent upwards, while it drops two 

 other rings, which in their turn go through the same series of changes, 

 until the figure becomes almost too complicated to follow. This is a 

 very common result with a moderately weak solution of cochineal ; 

 with a stronger solution the figure undergoes some beautiful modifica- 

 tions. The heavier portions of the coloring matter collect not at two, 

 but at four, six, or even s..-von or fight points of the ring, bending it 

 upAvards in as many curved lines, and letting drop as many rings, 

 each of which becomes the scat of manufacture of two rings ; and in this 



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