Citemisiry and Mineralogy. 393 



The glass is again guarded by strong ribs of iron, so that the 

 lamp may be exposed to considerable shocks without danger of 

 injury. A contrivance was also described by which the air was 

 allowed to enter from below, by means of a gauze tube, but so 

 managed, that the gauze could not be reached by the workmen. 

 Various improvements upon the Davy lamp were noticed by 

 different members. Mr Graham stated, that he had found that 

 when the gauze was steeped in an alkaline solution, the flame 

 was prevented from passing so readily, and corrosion was ob- 

 viated. He considered the only adequate provision against ac- 

 cident to be the employment of a double gauze cover. 



3. Mr Kane read a communication in reference to pyroxylic 

 spirit. The experiments which he had made upon this sub- 

 stance corroborate the opinion of its composition entertained by 

 Dumas and Pelligot, who term it methylene, viz. that it is a 

 compound of an atom of carbydrogen, and 1 atom of water, ha- 

 ving for its atomic weight 2. 



4. Mr Fox described an experiment which he had made with 

 regard to the effect of melted iron upon the magnet. He found 

 that no action was exerted upon it. Hence this is an argument 

 against the idea of a central fire. 



5. A letter was read from Dr Turner, reporting the opinion 

 of the committee appointed at last meeting to take into consi- 

 deration the adoption of a uniform set of chemical symbols for 

 this country. The opinion of the majority was, that those used 

 on the Continent should be had recourse to. It was strongly 

 recommended that the abbreviations should not be carried fur- 

 ther than the dots for oxygen ; indeed, it was suggested by some 

 that these should be rejected, as they merely express theory, and, 

 consequently, vary according to the view that is taken of the 

 composition in this country and on the Continent ; but it is ob- 

 vious, that if brevity is not carried any further than this, no bad 

 consequences can follow from a system of notation. Dr Thomas 

 Thomson strongly recommended that the centigrade thermome- 

 ter should be adopted in this country for scientific purposes, as 

 being infinitely better adapted for such purposes than that of 

 Fahrenheit. His suggestion appeared to coincide exactly "with 

 the opinion of the Committee. 



