109 GYPSUM. 
interiors of their palatial mansions. The stately columns and 
pedestals, as well as much of the wall facings, stair banisters, and 
statuary are wrought from it. It is soft—is easily worked into 
any required shape and is effective. At Castelino, in Italy, about 
35 miles from Leghorn, it is found fairly massive, but whether 
it is from this source, or from Fauld, that material for the 
internal decoration of the Roman villas was obtained, I am not 
prepared to say. We only know that there was a Roman settlement 
at Hanbury (near to Fauld), and we know that Gypsum was mined 
there by the Romans, Of course, I do not pretend to say that it was 
where the present mines are, for, as is well known, Gypsum lies under 
Hanbury in large masses, and round to Draycott, if not all round 
the forest escarpment. 
The widely distributed variety occurs naturally in the crystal- 
lised or crystalline form, the massive kinds are confined to localities, 
and are amorphous semi-translucent masses. 
Let us consider a few of the properties of the mineral more 
closely, so far, at least, as will enable us to have an understanding 
of the matter which occupies us to-night—the formation of Gypsum. 
Gypsum is soluble in water. A gallon of pure water will dissolve 
about 200 grains of it. Further, Gypsum contains water. We may, 
therefore, conclude that water percolating through any strata con- 
taining Gypsum will become impregnated with it, and hence it is 
that the water from some of the deep wells in Burton contains 
Gypsum in large quantities. We may also conclude that if such a 
water be evaporated the Gypsum will separate in crystals, if the 
evaportion is slow, probably in large crystals, if rapid and under 
pressure in crystalline masses. This can be easily observed with a 
microscope. When Gypsum crystallises slowly, as in loose clay like 
Oxford clay, it assumes well defined forms of the Monoclinic system. 
Some of these occurring in London and Oxford Clays and Lias are 
large, bold and well defined. 
