120 Dr. Apjohn on a new Compound of Iodide of Potassium. 



As the conjoint result, therefore, of our analysis and our hypo- 

 thesis we find the formula for oil of cinnamon to be Cj^ Hg.ss 

 Oj gg. Now this is so close to the formula of Dumas, viz. C^g Hg 

 Og, particularly when we consider that owing to the fusibility 

 of the compound, and the facility with which it is decomposed, 

 heat could not be applied in drying the contents of the tube 

 before the commencement of the combustion, and that conse- 

 quently the hydrogen must have been too high and the oxygen 

 too low, — considering this, I say, the accordance is so close 

 as to leave no doubt that the empirical formula already given 

 correctly represents the constitution of the compound submitted 

 to analysis. It is scarcely necessary to say that the most pro- 

 bable rational formula is that here subjoined: 

 IK + 3(t + Cin2). 



From the analysis which I first performed, and of which I 

 gave a brief account in the Chemical Section at the Liverpool 

 Meeting of the British Association for the Advancement of 

 Science, the formula deduced was 



IK + 2 (I2 + Cing), 



which differs from the preceding merely in containing one 

 more atom of iodine. 



This compound appears interesting under many points of 

 view. In the first place it is one of considerable complexity, 

 is decomposed with an extreme facility, and is nevertheless 

 perfectly definite in its composition, and even beautifully cry- 

 stallized. 



In the second place it is a kind of double salt, composed of 

 two haloid salts, in one of which the oil performs the very 

 unusual function of an electro-positive or basic metal, — a cir- 

 cumstance the more singular, as Dumas has shown that it 

 unites also to the muriatic and nitric acids, forming with them 

 binary compounds, the latter of which very readily crystal- 

 lizes. The oil in fact thus appears to act the part of a metal 

 as well as of an oxide. 



Lastly, I may observe that the method by which our com- 

 pound was first accidentally formed, and is still best made, 

 presents an instance of incompatibility which had not been pre- 

 viously suspected, and will no doubt suggest to chemists ex- 

 periments which will eventuate in the production of a series 

 of similar substances. In reference, however, to this latter 

 point I should add that Mr. Moore has applied to the other 

 aromatic waters the very process which succeeds with cinna- 

 mon water, but without obtaining a trace of any new product. 

 It is possible, however, that new results might be obtained 

 by substituting other metals for the potassium, and replacing 



