A SYNOPSIS 



MINERALOGY OF STAFFORDSHIRE. 



EARTHS, including stones, form aggregates: the surface-soil 

 is composed of clay, colorific earth, marl, and mould. Clay 

 is a decomposition of the primitive stones with other matter, 

 silica alumina, carbonate of lime, oxyd of iron, carbonate of mag- 

 nesia, water, and air. The colorific earths are composed of clay 

 and oxyd of iron. Marl is a mixture of carbonate of lime and clay. 

 Mould, the soil on which vegetables grow, contains silica alumina, 

 lime, magnesia, sometimes iron, but always carbon, derived from 

 decayed vegetable and animal substances, and carbonic acid and 

 water. 



Giobert the chemist, found a fertile soil near Turin to contain 

 78 parts silex (sand), 12 alumina (clay), and 8 to 9 lime, the 

 whole being supposed 100 parts: the annual rains there 30 inches. 

 Near Paris, where the rains are 20 inches, M. Tillet found 46 parts 

 silica, 16| alumina, 37f lime : total, 100. 



The four Earths, silica, alumina, lime, and magnesia, are the 

 principal basis of soils. If silica most abounds, the soil is dry ; if 

 alumina preponderates, the soil is wet : lime and magnesia are cor- 

 rectors ; they increase the moisture of land, and diminish the wet- 



la compiling this article, it will be seen that the excellent letter of Mr. 

 Keir, communicated by that gentleman to Mr. Shaw, and published in his 

 " Antiquities of Staffordshire," has been had recourse to ; and it may be proper 

 to add, with the entire concurrence of the venerable writer, who would cheer- 

 fully have gone into the subject a second time, and furnished us with whatever 

 uggesled itself, if age and bodily infirmity did not prevent him from accom- 

 plishing so laborious a task. Some apparent inaccuracies will be accounted 

 for in the altered circumstances of the times, but these do not in the least affect 

 the substance of this very able and elaborate view of the mineral treasures 

 of this county. 



