546 



Dr. J. H. Gladstone and A. Tribe. 



[June 17, 



again increasing the pressure to 73 atmospheres. On now rapidly 

 letting down the temperature to 15° C. a white mass of camphor sepa- 

 rated out from the liquid, which again dissolved on a slight increase of 

 pressure, although it could not be again separated out by diminishing* 

 it. These actions may be due, in part, to supersaturation and the 

 effect of pressure in aiding solubility when contraction takes place 

 during solution. 



These experiments show that carbonic acid at high pressures in 

 presence of various substances acts as if it produced a series of un- 

 stable chemical compounds, which are decomposed and recomposed 

 according to the conditions of temperature and pressure in the 

 medium. Further observations are required to elucidate many obscure 

 actions taking place under such conditions of experimenting as are 

 detailed in the above communication. 



IV. " The Aluminium-Iodine Reaction." By J. H. GLADSTONE, 

 Ph.D., F.R.S., and Alfred Tribe, F.C.S., Lecturer on 

 Chemistry in Duhvick College. Received June 10, 1880. 



About four years ago we pointed out a reaction of iodide of alumi- 

 nium which, as far as we are aware, has no precise analogue in the 

 science of chemistry, and which has led to the discovery of several 

 volatile aluminium alcohols. It is well known that neither water, 

 alcohol, nor ether is decomposed by metallic aluminium, and that each 

 of these bodies will dissolve iodine without entering further into com- 

 bination with it ; but we found that by the joint action of these two 

 elements, it was possible to split up the above-mentioned liquids. 

 Water, though forming a definite hydrate with the iodide of alnmi- 

 nium, is decomposed by it in the presence of an excess of the metal, 

 hydrogen being evolved and aluminic hydrate formed. This takes 

 place at the ordinary temperature. 



Alcohol in a similar manner is decomposed by the joint action of 

 metallic aluminium and its iodide, with the ultimate production of 

 hydrogen gas, aluminic ethylate, and varying amounts of aluminic 

 iodoethylate proportional to the quantity of aluminic iodide employed. 

 A small quantity of the iodide suffices to bring about the formation of 

 a very large amount of the ethylate ; in fact, the process would be a 

 continuous one, were it not that the solid products gradually put a 

 stop to the reaction. 



Ether is not affected by aluminic iodide and aluminium, but when 

 exposed to iodine and aluminium simultaneously it suffers a violent 

 decomposition, iodide of ethyl and the aluminic iodoethylate being 

 the ultimate products. 



Amylic ether behaves in a similar manner, and the acetates of ethyl 

 and amyl give analogous results ; but the reaction is not an ordinary 



