EARTHS. CALCAREOUS. 22. Marga. 



97 



Common in fpongy places, and may probably have its origin in 

 the rotten roots of plants : it takes a long time in drying, and 

 is a bad foil for the farmer or gardener, becaufe in the fpring 

 Ibalbn it intamefces by the frolt at night and the heat by day, 

 and lifts up and eradicates the fmaller plants. 



Lutiwt. Very light, not combuflible, black when moift. 



Hum. veget. palud. Syst. nat, xii. 3,/>. 210. n. 7. 



Hum. accrof. palull. Wall, fyfi. min, \. p. 19, «. 5. 



Humus lacaftris. Cronli. miris feci, 293. B. 2. 



Found in fvvamps andmarfhes under water, and is produced by 

 the gradual corruption of bog-plants : it is fo light as to re- 

 main feme time fufpendco in water, and is ferviceable in 

 fandy foils. 



martialiu With a metallic tinge. 



Humus colorata. WalL/yst. min, I. p, 16. n. 2. 

 Syst, nat. xii. 3. /. 21 i. ». 8. 10. ^^ 



Found in various parts of Britain, Snjjeden, Germany^ Syria^ &Ci. 

 in fwamps and marfhes^ yellow- brown, reddilh, purpliih, ^t 

 black, which colour it receives from its contamination with, 

 oxydeofiron. 



piceg* Black) becoming folid as it dries. 



Found in Scamay often in the cultivated lands, and requires a 

 peculiar method of agriculture. 



muriatka. Brown, of a faltiOi tafte. 



Argilla muriatico-falfa. »S>y?, nat. xii. 3. p, 205. n. 20. 

 Terra e palasftina. Cronst. 7nin. p. 125. 



Found in the defaris on the confines of the Red-Jea, Egypt, and 

 Syria, 



terrea. 



22. MARGA. Confifting of carbonate of lime and 

 argil, with generally lome oxyde of iron; fbft, 

 opake, of a common form, internally earthy, 

 light and mifcible with common water by agita- 

 tion, found in ilratified mountains: pardy folu- 

 ble in nitric acid, with efFervefcence : hardening 

 in the fire, and vitrifying in a flrong heat. 



Friable, meagre, a little rough to the touch. 

 Argilla mixta. Syst, nat. xii. 3. p. 204, «. 17, 

 Marga friabilis. Cronst. min, p, 26. 

 Argilla rudis. Carthy min. 6. 

 Calcareous Marl. Kir-uoan miner, i. p, 94. 

 Earthy Marl, Schmei/Jer miner, i, p. 228. 



VOL, VIT. — N 



