118 PROCEEDINGS OF THE SOCIETY. 



glass, he did not see why the thin cover-glass, cemented on with Canada 

 balsam would not be better, as the irregularity of surface would not 

 obtain. 



Mr. Rawlins replied that his method was to take the section to be 

 varnished, with an old photographic plate, and on to that he put a blob 

 of plasticine, and set up the metal specimen. Usually it had a jagged 

 under-surface, and stuck readily to the plasticine. He then poured the 

 solution on to the polished surface. Observation was kept of any spot 

 at which there was a tendency for it to settle. The plate was tilted 

 backwards and forwards until the liquid settled in the centre. In thirty 

 minutes, especially if placed in a draught, it became quite dry, and free 

 from laminations or ridges, and penetrable up to l-th leus. The thick- 

 ness would be up to three-quarters of a cover-glass. If moi'e than one 

 drop were put to a cover-glass, it would be far too thick, and the 

 correction would be upset. This method, with ^th lens, did not land him 

 into any difficulties, and it preserved the specimen for an indefinite time. 

 There were no other inconvenient reflections. If a blob were allowed 

 to be in any one place, especially as it was apt to ba gummy at an 

 angle of something like 57°, it might start plane polarization. At first 

 he had difficulties because he used a camel-hair brush, which set up 

 ridges. With a concentrated solution, the preserving effect would not 

 be so good. He agreed that ordinary thin balsam would probably do 

 as well. He tried the method he had described because of a recipe he 

 got from a French photographist. He had, so far, only tried to use the 

 film as a preservative ; he could see the possibilities of trying it with a 

 cover-glass. 



A hearty vote of thanks was accorded to Mi-, Rawlins for his com- 

 munication. 



A paper by Mr, Ritchie (Acetone as a Solvent for Mounting) was 

 read in abstract by Mr. Scourfield. On the motion of the President 

 the Society thanked th» author for his communication. 



The President, as required by the By-laws, again read the motion 

 proposed at a previous meeting by Mr. Wilson, to empower the Council 

 to remove all alien enemy Fellows from the Society's roll. 



The President announced that the hour of the Meeting on March 

 20th would be 5.30, on account of the uncertainties in the conditions 

 for an evening Meeting during a bright moon. The alteration seemed 

 specially desirable as it was hoped the next Meeting, a special one, 

 would be largely attended, 



