gaged from bituminous shist, when it isworked.

The great sources of the fire-damp inmines are, however, what are called blowers*or fissures in the broken strata, near dykes,from which currents of fire-damp issue inconsiderable quantity, and sometimes for a

atmosphere, so that they give off elastic fluid when theyare exposed to the free atmosphere : and probably coalscontaining animal remains, evolve not only the fire-damp, but likewise azote and carbonic acid.

In the Apennines, near Pietra Mala, I examined a fireproduced by gaseous matter, constantly disengaged froma shist stratum : and from the results of the combustion,I have no doubt but that it was pure fire-damp. Mr.M. Faraday, who accompanied me, and assisted me inmy chemical experiments, in my journey, collected somegas from a cavity in the earth about a mile from PietraMala, then filled with water, and which, from the quan-tity of gas disengaged, is called Aqua Buja. I analysedit in the Grand Duke’siaboratory at Florence, and foundthat it was pure light carburetted hydrogene, requiringtwo volumes of oxygene for its combustion, and pro-ducing a volume of carbonic acid gas.

It is very probable, that these gases are disengagedfrom coal strata beneath the surface, or from bituminousshist above coal; and at some future period new sourcesof riches may be opened to Tuscany from this invaluablemineral treasure, the use of which in this country hassupplied such extraordinary resources to industry.