480 Prof. Johnston o?i an Analogy in Atomic Constitution 



tion with ammonia or potassium, are mixtures oftlie aetherine 

 with its sulphate in various proportions. As it is well known 

 that the odour of the essential oils is rendered more active by 

 dilution, the livelier smell of the solutions may be consistent 

 with a diminished proportion of the odoriferous matter. 



Oil of wine cannot be distilled ])er se without partial decom- 

 position, which does not take })lace below the temperature of 

 300°. When subjected to the distillatory process, over potas- 

 sium, at a certain temperature, a brisk reaction ensued, and 

 the oil and metal agglutinated into a gelatinous mass. By 

 raising the temperature the mass liquefied, and a colourless 

 oil came over, which retained the odour of oil of wine. Mean- 

 while some of the potassium remained unchanged, and ap- 

 peared within the liquid in the form of pure metallic globules. 

 On pouring into the retort a portion of nitric acid in order to 

 remove the caput mortuum, ignition took place from the pre- 

 sence of the potassium. 



LXXIV. On a supposed Analogy in Atomic Constitution be^ 

 tween the Earthy Carbonates and Alkaline Nitrates, By 

 J. F. W. Johnston, A.M., F.R.SS., L. Sf E., F.G.S., 

 Professor of Chemistry and Mineralogy in the University of 

 Durham.* 

 1 F we tabulate the knowledge we possess in regard to those 

 *■ dimorphous compounds, which in the crystalline state 

 assume the two forms of arragonite and calc spar, we shall 

 have the followinor table. 



In this table we have a universal analogy in form, but in 



regard to one substance K N a remarkable difference in che- 

 mical constitution. How is this difference to be reconciled 



» Communicated by the Author. 



t G. Rose in Poggenclorft"*s Annalerif xlii. p. 366. {ante p. 474.]. 



