14 Mr, Scanlan on a Compound of Iodine and Carbon, [July, 



Article II. 



0/1 a Compound of Iodine and Carbon. By Mr. M. Scanlan. 



(To the Editors of the Annals of Philosophy.) 



GENTLEMEN, Dublin, Jpril2\, 1825. 



In contriving a process for making iodide of potassium, 

 which struck me as less objectionable tJnan those with which I 

 was already acquamted, I have formed a combination of iodine 

 and carbon which, so far as I know, has not been described by 

 chemists. 



It may be thus obtained : 



Add to an alcoholic solution of iodine caustic potash till the 

 colour be destroyed, the liquor becomes turbid, and a white 

 crystalline deposition ensues which is iodate of potash : distil, 

 with a very gentle heat, the alcohol from the clear liquor which 

 is yellowish ; and on cooling, this substance is deposited in 

 small micaceous plates, opaque, and of a bright sulphur-yellow 

 colour: the solution ofhydriodate of potash retains obstinately 

 a portion of it which cannot be separated without decomposition. 



Iodide of carbon, if I may so name it, has a powerful and 

 aromatic odour somewhat resembling saffron. It is soluble in 

 alcohol, and precipitated therefrom by water yellowish-white. 

 It rises in distillation with water unchanged, but is readily 

 decomposed by a heat little higher than boiling water. Exposure 

 on a piece of writing paper over the flame of a candle renders 

 visible the violet vapour of iodine : heated in a glass tube, it melts, 

 and is decomposed ; iodine sublimes leaving carbon. 



Heated with iron or zinc, an iodide of the metal is formed. 



Its alcoholic solution by spontaneous evaporation yields slen- 

 der prismatic crystals. 



I have not yet made any very satisfactory experiments to 

 ascertain the proportions of its elements, but it appears to me, 

 from such trials as I have made, that the best method of analysis 

 would be to expose it to a sufficient heat in a sealed tube mixed 

 with iodide of potassium ; the iodine sublimes into the cooled 

 end, and the carbon may be separated from the iodide by means 

 of water. 



In this way the weight of each element might be determined 

 in the one operation. M. Scanlan. 



Note. — Mr. Faraday has had the goodness, at my request, to 

 examine the specimen of the supposed iodide of carbon, for- 

 warded to us by Mr. Scanlan. Ihe following is the report we 

 have been favoured with by him on the subject. Our readers 

 will recollect that we owe the discovery of the hj/driodide of car^ 

 bon to Mr. Faraday.— C. 



