72 Lit Ilia. — Alloys of Plaiinum. — Explosion in a Coal- Mine. 



LITHIA. 



Mr. Berzelius has given the following method of proving 

 whether this new alkali be present in any mineral : A small frag- 

 ment of the mineral, of the size of a pin's head, or a little of its 

 powder, with a small excess of soda, is to be heated by a blow- 

 pipe, for two minutes, on a piece of platinum foil. The mineral 

 is decomposed, the lithia liberated by the soda ; and the whole 

 being kept fluid, at this temperature, by the excess of alkali, it 

 spreads over the foil, surrounding the decomposed mineral. The 

 part of the platinum near to the fused alkali becomes of a dark 

 colour, more or less intense, and over a greater or less part of the 

 surface, proportioned to the quantity of lithia in the mineral. 

 This oxidation of the platinum takes place only around (not un- 

 der) the alkali, where air as well as the lichia has access to the 

 metal. Potash destroys the reaction of the platinum on the li- 

 thia, if the latter be not abundant. The platinum being washed 

 and heated, resumes its metallic surface. 



ALT.OYS OF PLATINUM. 



It results from some experiments by Mr. Fox of Falmouth, that 

 if about equal bulks of platinum and tin, in contact with each 

 other, be heated to redness, they combine suddenly with gieat 

 vehemence, and a considerable extrication of light and heat, 

 which continues for some time after they are removed from the 

 fire. This experiment may be jierformed by enveloping a piece 

 of tin in platinum foil, and exposing it on a piece of charcoal to 

 the flame of a blow-pipe : a kind of explosion takes place at the 

 moment of combination, and the alloy runs about like ignited 

 antimony. 



Similar effects take place with platinum and antimoiiy. This 

 alloy, when highly heated for some time, becomes solid "and very 

 malleable, and then contains but little antimony. 



Zinc produces the same phaenomena, exploding and burning at 

 the moment of combination. 



DREADFUJ. EXPLOSION IN A COAL-MINE. 



It is our painful duty to notice another of those distressing ac- 

 cidents which so irequently occur in coal-mines. On Tuesday 

 the 20th July, owing, it is reported, to some neglect or misma- 

 nagenoent regarding the safety-lamps in the Sheriff-hill pit, at 

 Gateshead near Newcastle-on-Tyne, a dreadful explosion took 

 place, by which nearly 40 persons have lost their lives. Had 

 the accident happened an hour later, it is said about lOG persons 

 would have perished. 



BLASTING 



