Inflammables. 219 



and when frefli of a vifcid confidence, but 

 hardens by expofure to the air ; it confifts of 

 clay, mixed with calcareous earth and py- 

 rites, and fometimes contains common fait; 

 while foft it is formed into oblong pieces, 

 and the pyritaceous and ftony matters are fepa- 

 rated ; when diftilled it affords water, acid, 

 oil and volatil alkali, and its afhes contain a 

 fmall proportion of fixed alkali ; they are 

 either white or red according as it contains 

 more or lefs ochre or pyrites. 2 Ed. EJfays, 

 244. 2 Gerh. Beytr. 265. It is found in 

 Scotland, Holland, and Germany. Another 

 fort is found near Ne r wbury in Berk/hire ; it 

 contains but little earth, but confifts chiefly 

 of wood branches, twiggs, roots of trees* 

 with leaves, grafs, ftraw and weeds. Phi!. 

 Tranf. 1757. p. no. 



SPECIES XII, 

 Turf. 



This confiPts of mould interwoven with the 

 roots of vegetables ; when thefe roots are of 

 the bulbous kind, or in large proportion, 

 they form the loofer and worft kind of turf; 

 but when mixed with a confiderable propor- 

 tion of peat, they form what is called jfcwkf 

 turf", it at firft hardens, but at laft crumbles 

 by long expofure to the air. 



SPECIES XII& 



