82 CHEMICAL AN ALTSIS 



Q. The two portions of white earth above mentioned, which 

 feemcd to be carbonate of lime, weighed together i6 grains. 

 To feparatc magnefia, if any were mixed with this earth, I put 

 it into a httle water, and added fulphuric acid till flightly in ex- 

 cels. Sulphate of lime was produced. Having poured fome 

 alkohol into this mixture, I filtered it, and waflied the fulphate 

 of lime with more alkohol diluted with water. The filtered li- 

 quor was then boiled with carbonate of foda, but no magnefia 

 was precipitated. 



These i6 grains were therefore carbonate of lime, of which, 

 according to Mr Klaproth's calculation, about g grains were 

 pure lime. 



One hundred parts of the bafalt of StafFa contain, according 

 to the above analyfis : 



Silex, - (No. 4. 7. and §.). - 48 



Argil, - (No. 7. and 8.). - 16 



Oxydofiron, - (No. 8.). - - 16 



Lime, - (No. 9.). - - 9 



Moifture, and other vol, matter, - - 5 



94 



The fum is 04 parts ; confequently there is a lofs of 6 p6r 



cent. 



About a year ago I analyzed fpecimens of fome of the whins 

 in the neighbourhood of Edinburgh, and found, that the fum 

 of the earths and iron, feparated by the analyfes, never amount- 

 ed to more than 93 or 94 per cent. ; fo that the lofs was 

 always equal to that juft mentioned. It was this circumftance 

 which fivft led me to fufpeft that fome ialine fubftance exifted 



in 



