xiv. Proceedings. [April \st, 19 19. 



Extraordinary General Meeting, April ist, 1919. 



The President, Mr. William Thomson, F.R^S.E., RI.C, F.C.S., 

 in the Chair. 



At this Extraordinary General Meeting, summoned in 

 .accordance with the Articles of Association, the following 

 resolutions of the Council were submitted to the :Society: — 



1. "That a new honorary office of Curator be insti- 

 tuted — the holder to be ex officio a member of the 

 Council." 



2. '■ That the number of ordinary members of the 

 Council be increased from six to nine." 



These resolutions were adopted. 



Ordinary Meeting, April ist, 191 9. 



The President, Mr. William Thomson, F.R.S.E., F.I.C., F.C.S., 

 in the Chair. 



Mr. S. Lees, M.A., read a paper entitled "The Super- 

 posing of Two Cross-line Screens at Small Angles and 

 the Patterns obtained thereby." 



This paper is printed in full in the Mevioirs. 



A paper on " Electrolytic Iron Deposition " was read by 

 Lieut. W. A. Macfadyen, M.C, B.A. 



The investigations were carried out with a view to 

 finding the best means of obtaining hard and adherent 

 deposits of iron on worn steel mechanism parts, so that the 

 latter could be returned to use, instead of being scrapped. 



Deposition from dilute, cold, aqueous solutions of 

 Ferrous Ammonium Sulphate, containing 50 to 100 grams 

 of the salt per litre, gave excellent results, but the process 

 was very slow. 



Solutions of intermediate concentrations gave poor 

 results, but concentrated solutions of 300 to 400 grams of 

 the salt per litre, gave results as good as those obtained in 

 the dilute bath, and aboiit 7 times as rapidly. The acidity 

 of the solution should be kept about -005 Normal with 

 respect to Sulphuric acid; i.e., if concentrated Sulphuric 

 acid of Sp.G. 1-827 be used, as addition, -1467 cc. per litre 

 of solution must be added. Subsequent additions must be 

 made at intervals, as the acidity diminishes under working 

 conditions. 



