NOTES ON THE MINERALS FOUND NEAR BRISTOL. "3 



Clevedon^ where this singular mineral occurs in a very pure state, 

 the Carbonates of Calcium and Magnesium are combined in 

 nearly atomic proportions. In this case the Dolomite has a 

 delicate buff colour, and granular or pseudo-oolitic structure. 



Dolomite may be known by the extraordinary circumstance that 

 although the Carbonate of Calcium, and Magnesium, taken separately 

 efferv^esce strongly on the addition of an acid, yet the dolomite 

 which is simply a mixture of the two in atomic proportions, shews 

 hardly any reaction. Indeed, should any marked effervescence be 

 caused by the addition of a dilute acid,'it is a sure indication that the 

 specimen contains an excess of lime. This '^curious peculiarity 

 was mentioned by Dr. Percy in a lecture delivered in 1854. 



The composition of the Clifton and Clevedon dolomites is 

 shewn by the following analyses • — 



I have made some very pure specimens of Epsom Salts by 

 adding to the dolomite warm diluted sulphuric acid, the result 

 being the formation of insoluble Sulphate of Calcium, and soluble 

 Sulphate of Magnesium. The latter is, therefore, easily obtained 

 by decantation and evaporation. 



COFFER. 



All the ores of this metal that I have seen are in the form of 

 Malachite, or the hydrated dibasic carbonate (Cu. O, H2O, Cu. 

 CO3). A great number of beautiful specimens may be collected 

 in the Clevedon quarry, behind the Hotel. They are found in 



