1874.] Dr. J. Stenhouse on the History of the Orcins. 53 



considerable decomposition during distillation, I analyzed, in preference, 

 a portion of the remainder, which had not been distilled, having pre- 

 viously dried it at 100, and agitated it with metallic mercury to remove a 

 trace of free iodine. The following are the results of the analysis : 



C S;? L Experiment. 



C 7-64 7-67 



H 0-96 1-11 



This is a colourless oily liquid ; like the others it has a sweet and 

 biting taste. Its specific gravity at 29 Cent, is 2-86. Heated to the 

 temperature of 100 in a sealed tube with moist oxide of silver it occa- 

 sioned a violent explosion. Heated in an open retort with the same 

 body, it evolved carbonic acid gas and bromide of vinyl. 



II. " Contributions to the History of the Orcins. No. IV. On 

 the lodo-derivatives of the Orcins." By JOHN STENHOUSE, 

 LLJX, F.R.S., &c. Received November* 10, 1873. 



A preliminary notice on these compounds has already appeared in the 

 * Chemical News,' vol. xxvi. p. 279 ; and the present paper contains a more 

 detailed account of my experiments. 



In 1864* I published an account of a crystalline teriodorcin obtained 

 by precipitating an aqueous solution of orcin with a solution of iodine 

 monochloride, but I found I was unable to prepare any other iodine 

 derivative of orcin by this process. It seems probable, however, that 

 the method devised some years ago by Prof. Hlasiwetzf, and commu- 

 nicated by him at the meeting of the " Naturforscher und Aerzte in 

 Innsbruck," would yield the lower substitution compounds. This was 

 found to be the case ; for on agitating an ethereal solution containing 

 equal molecular weights of orcin and iodine with dry precipitated mer- 

 curic oxide, the colour rapidly disappears, and monoiodorcin is formed ; 

 this may be obtained by distilling off the ether and crystallizing the 

 residue from benzol, in order to separate an uncrystallizable oily com- 

 pound which accompanies it. It is, however, still contaminated with a 

 small quantity of mercuric iodide, which obstinately adheres to the sub- 

 stance, and can only be removed by recrystallization from a dilute aqueous 

 solution of potassium iodide ; this difficulty arises from the circumstance 

 that mercuric iodide is more or less soluble in most of the liquids usually 

 employed as solvents. For this reason I found it advisable to substitute 

 plumbic oxide for the corresponding mercury compound originally pro- 

 posed by Hlasiwetz. 



Monoiodorcin, C 7 H 7 1 O 2 . One part of pure dry orcin is dissolved in 



* Journ. Chem. Soc. vol. xvii. p. 327. t Deut. chein. Ges. Ber. II. 551. 



F2 



