the marble has the property of remaining in the same place at common temperatures, which water-steam has not. If I add a little liquid to the marble, and decompose it[1], I get that which you see—[the Lecturer here put several lumps of marble into a glass jar, and poured water and then acid over them; the carbonic acid immediately commenced to escape with considerable effervescence]—the appearance of boiling, which is only the separation of one part of the marble from another. Now this [marble] steam, and that [water] steam, and all other 
Fig. 2.steams gravitate, just like any other substance does—they all are attracted the one towards the other, and all fall towards the earth; and what
- ↑ Add a little liquid to the marble, and decompose it.—Marble is composed of carbonic acid and lime, and, in chemical language, is called carbonate of lime. When sulphuric acid is added to it, the carbonic acid is set free, and the sulphuric acid unites with the lime to form sulphate of lime.
Carbonic acid, under ordinary circumstances, is a colourless invisible gas, about half as heavy again as air. Dr. Faraday first shewed that, under great pressure, it could be obtained in a liquid state. Thilorier, a French chemist, afterwards found that it could be solidified.
