512 Analyses — Tin from Malacca. [Sept. 



The mineral was found to differ considerably in weight from the 

 statements of Thomson and Phillips — the specific gravity of two 

 specimens being 2*970, and 2*897, at the temperature of 8^°. A good 

 deal of air was given off on its first immersion into water, and it adhered 

 to the tongue. 



Another point to be ascertained, from this mineral, was, whether the 

 circumstance I noticed on the occasion alluded to, would hold true, viz. 

 that calcined magnesia would not become a hydrate, like lime, on slak- 

 ing, and that this earth might thus be recognized in mixtures. 



Three of the calcined specimens were treated with water, which dis- 

 engaged considerable heat, and then exposed in a receiver, over concen- 

 trated sulphuric acid, to be ridden of hygrometric moisture. After 30 

 hours, they weighed respectively 60*45, 58*7, 60 9 grs., shewing an 

 average excess of 10*0, which is about half an atom of water (98). 

 This result is so unexpected that it requires further examination, which 

 I hope to be able to give hereafter. 



3. — Tin from Malacca. 



Cast blocks of the metal of the principal mines, as prepared for 



sale, were transmitted by Ensign Newbold. With reference to my 



observation in the 3rd vol. of the Gleanings, I was contented to test 



their purity by the specific gravity, which was as follows : — puie tin, 



at the same temperature, 84°*5, being about 7 290 



No. 1, from Naning 7*317 



No. 2, ,, Sriraenanti (new mine) 7*262 



No. 3, ,, Jompole 7287 



No. 4, ,, Sungie Oojong 7*223 



No. 5, ,, Lukutin Salangore 7*349 



No. 6, ,, Rumbowe 7*256 



No. 7, ,, Jelaboo 7*314 



No. 8, ,, Perak 7299 



Two specimens of the ore also accompanied : — 

 No. 1, from Lukut, a fine grained black oxide of tin, had a speci- 

 fic gravity of 6* 74, and yielded a produce of 70 per cent, of very good 

 metal, on simple fusion, with black flux. 



No. 2, from Srimenanti, was in much larger grains or lumps. It 

 weighed, however, only 6*64 ; and yielded only 52j (?) per cent, of 

 metal — giving off some sulphur in the fire. It is therefore inferior 

 to the former, but probably not to the extent stated in the above crude 

 and single reduction. 



4. — American Self-generating Gas Lamp. 

 Mr. Longueville Clarke has one of these curious and ingenious 

 lamps, which are something on the principle of the little floating 



