May 1 8th, 1920.] Proceedings. xxv. 



amalgamation with mercury. He observed that the tempera- 

 ture during oxidation rose to 102 ° C, that it was the hydrated 

 oxide of aluminium which was formed, that this oxidation took 

 place only in damp air or oxygen, and that an exceedingly 

 minute quantity of mercury effected the complete oxidation of 

 the aluminium. He mentions that he could find no reference 

 to the properties given to aluminium by mercury in any of the 

 most accredited treatises ; he consulted the eminent chemist 

 M. Ditte, Professor of Chemistry at the Sorbonne, the author 

 of the most complete and recent work on the properties of 

 aluminium, but he knew nothing of the facts Le Bon had 

 pointed out, who therefore assumed that he was the first to 

 publish anything about it. 



We found that for these growths to take place both oxygen 

 and moisture must be present simultaneously. Thus, they will 

 not grow in damp hydrogen or carbon dioxide, nor will they 

 grow in air which has been dried by passage through concen- 

 trated sulphuric acid, nor at an elevated temperature of — say — 

 75 C. In damp air containing ether vapour the growths are 

 restricted. They are not formed at all in chlorine gas ; and a 

 trace of hydrochloric acid or of ammonia in damp air prevents 

 the growths. Much heat is evolved during the development of 

 the growths. We found the best results to be obtained by 

 amalgamating the aluminium with Nessler's solution, which is 

 an alkaline solution of mercuric chloride in potassium iodide. 

 In such a case 100 parts by weight of wire gave a growth 

 weighing 93.91 parts, the wire left weighing 67.76 parts, so that 

 32.24 parts of aluminium had become oxidised into alumina, 

 whilst the mercury left in the 67.76 parts of wire amounted to 

 0.62 part. A neutral solution of mercuric chloride answers this 

 purpose ; but the growths are not so profuse as when an alkaline 

 solution is used. If, after passing through the mercuric solu- 

 tion the wire be then passed through a drop of metallic mercury, 

 a still better growth is obtained. 



It was observed that the growth never takes place over the 

 whole surface of the wire ; but tends to concentrate itself along 

 one side or sometimes two sides of the amalgamated wire when 

 this is lying on a flat surface ; whilst in the case of an amalga- 

 mated wire suspended freely or fixed upright, 3 lines of growth 

 at angles of 120 from each frequently develop. 



When an amalgamated wire is placed for two hours in dry 

 air the mercury originally present on the surface presumably 

 sinks into the aluminium and when the wire is afterwards 

 exposed to damp air no growth takes place. 



When aluminium foil is amalgamated and put in water it 

 rapidly becomes converted into the hydrated oxide, which 



