IODINE FOR HYDROGEN IN ORGANIC COMPOUNDS, &C. 55 



The decomposition by which iodoraecone is produced from pyromeconic acid, 

 now becomes obvious. It is represented by the following equation : — 



C 10 H 4 6 + 8 I Cl + 8 HO = C 6 H 4 I 8 G + 4 C0 2 + 8 HC1 



This being the mode of its formation, it seemed probable that meconic and 

 comenic acids, which differ from pyromeconic acid only by the elements of carbonic 

 acid, would yield the same substance, when acted on by chloride of iodine. Ac- 

 cordingly, I have found that it is immediately produced with all its characteristic 

 properties from these acids, by the same process. The relations of this substance 

 to meconic and pyromeconic acids, are of a very remarkable character, and can- 

 not at present be distinctly brought out. It obviously belongs to the same class 

 as the very curious product obtained by Cahours, by the action of bromine on 

 citric acid, and which he has called bromoxaform. According to this chemist, 

 when bromine is added to citrate of potash, effervescence takes place from the 

 evolution of carbonic acid, and on the addition of potash, an oily matter is thrown 

 down, which consists of three substances, one bromoform, the other a crystalline 

 solid bromoxaform, and the third apparently an accidental product, for it is ob- 

 tained in too small quantities to admit of examination. It can scarcely be doubted 

 that bromoxaform would be the only product, if the action could be properly 

 moderated, and that the bromoform is a secondary product of the former substance, 

 from which indeed it is readily obtained, by treatment with caustic potash. If 

 this be the case, the decomposition of citrate of potash would be quite analogous 

 to that of pyromeconic acid, as represented in the equation : — 



C 12 H 5 K 3 Q 14 + 2HO + Br 14 = C 6 HBr 5 4 + 6 C0 2 + 3KBr + 6HBr. 



Citrate of Potash. Bromoxaform. 



The relation which these curious substances bear to their parent acids is very 

 obscure, and cannot be elucidated without further experiments. In regard to 

 iodomecone, the small quantity in which I was able to obtain it, has prevented 

 my following out its decompositions as I could have wished, but I propose extend- 

 ing this investigation to some of the stronger acids by which means some light 

 may probably be thrown upon the constitution of these bodies. 



It was my desire to have extended my examination of the iodine substitution 

 products obtained by chloride of iodine, to some other substances. As yet, how- 

 ever, I have only tried codeine ; but the instability of the compound produced has 

 occasioned such difficulties, that I have hitherto been unable to arrive at satisfac- 

 tory results. When chloride of iodine is added to a concentrated solution of hy- 

 drochlorate of codeine, a fine yellow crystalline precipitate makes its appearance. 

 It is insoluble in water, but readily soluble in boiling alcohol. If this solution is 

 carefully effected, and too much of the substance be not added, it crystallizes on 

 cooling in stellar groups, of a fine red colour, but if a large quantity is dissolved, 



