TRANSACTIONS OF SECTION B. Ill 



sheet-irou, enclosed in a glass tube, through which a current of 

 hydrogen was made to pass. The glass was blackened opposite 

 the joint of the roll, and on taking out the latter and opening 

 it some of the magnesium was found sublimed in beautiful 

 glistening crystals. 



The first four attempts to make magnesium ethyl were 

 modifications of Hallwachs and Schafarik's and Cahours's 

 experiments, depending on the action of magnesium on ethyl 

 iodide, the reaction that was expected to take place being — 



2aig + 2C0H5I = Mgl2 + Mg(C3H5)2 ; 

 or 



f Mg + C0H5I = MgCaHsI. \ 



\ 2MgC2H5l = Mgia + Mg(C2H5)2. / 



Experiment 1. 



The apparatus for this experiment, as well as for experi- 

 ments II., III., and v., consisted — first, of a flask of 150cc.- 

 200cc. capacity ; secondly, of a condenser, the tube of which 

 was about 5mm. in diameter, and bent at right angles near one 

 end to allow of its being fitted to the flask by means of a cork, 

 through which were also fixed a tube for passing dry hydrogen 

 or carbonic acid, and a thermometer ; and, thirdly, of a re- 

 ceiver, which consisted of a small distillation-flask fitted to the 

 distal end of the condenser by a cork. To the side tube of this 

 flask a mercury valve was attached to exclude air. The con- 

 denser could thus be used either as a reflux or an ordinary 

 condenser. Great care was taken to have both apparatus and 

 materials thoroughly dry. 



Five grams of magnesium-filings were placed in the flask, 

 which was then attached to the condenser ; and the whole ap- 

 paratus was filled with carbon dioxide. Thirty grams of ethyl 

 iodide were now added, the cork being raised to admit it, and 

 a moderately rapid current of carbon dioxide being kept up to 

 prevent entry of air. There was thus slight excess of magne- 

 sium. No elevation of temperature was noticeable on contact 

 of the iodide with the magnesium ; and no appreciable action 

 took place in the cold. 



The flask was heated in an oil-bath to 75°-100°, till no more 

 ethyl iodide was seen to run back. This took thirty hours, 

 during which time a pretty constant slow stream of gas escaped 

 at the mercury valve. This gas burnt with a luminous flame 

 when ignited. At the end of the reaction a white residue 

 remained in the flask. The condenser was then reversed ; but 

 nothing except a little unused ethyl iodide came over, although 

 the temperature of the oil-bath was allowed to rise to 250°. An 

 alliaceous smell was, however, noticed. The residue consisted of 

 anhydrous magnesium iodide and unacted-on magnesium, with 



