1814.] Scientific Intelligence. 155 



having no other lead at hand than a quantity of the sheet lead which 

 comes from China wrapped around tea in the tea-boxes, I employed 

 it for my purpose. I was surprised to find it alloyed with tin, and 

 had the curiosity in consequence to subject it to chemical analysis. 

 The composition of this alloy docs not appear quite uniform. One 

 specimen I found composed of 



Lead 95-8 



Tin 4-2 



100-0 



Another consisted of 



Lead 95-18 



Tin 4-82 



r\ 



100 00 



We may conclude, with considerable probability, that the quan- 

 tity of tin added to the lead by the Chinese is 4 5 per cent. The 

 addition of tin to lead renders that metal harder, and gives it more 

 tenacity. The alloy does not seem so liable to tarnish as pure lead. 

 There is another advantage which attends the addition of tin to 

 lead. It renders that metal less injurious when it comes in contact 

 with articles of food ; for the tin is always acted upon in preference 

 to the lead. 



II. Native Carbonate of Magnesia. 



Some time ago, when at the India House, I obtained a quantity 

 of a white mineral, partly in lumps and partly in powder, which 

 was distinguished by the name of native carbonate of magnesia, 

 from India. I could not get any accurate information respecting 

 the place where it is found, nor who distinguished it by the name 

 of native carbonate of magnesia. It has more the aspect of Spanish 

 whiting than of carbonate of magnesia; being destitute of that 

 elasticity which constitutes so remarkable a character in magnesia. 

 It feds light, but not so much so as magnesia. Jt has not the least 

 resemblance to the native magnesia of Werner. The colour is 

 white, with a very slight shade of yellow. The lumps are all 

 rounded, as if they had been subjected to attrition. The fracture 

 U earthy, and precisely similar to that of chalk. The mineral 

 adheres to the tongue. 



On subjecting this mineral to analysis, I found it composed of 



Carbonate of magnesia 72 



Carbonate of lime 28 



100 



III. Vein of Filroui Limestone in Chalk. 

 Some weeks ago 1 received from Or. Leach, of the British 



