On the A''ew Jersey Marls, 



ascertaining the goodness of marl. Put some of it in a 

 glass, and wash it repeatedly until the water connes off 

 clear, then, by a magnifying glass, the proportion of sand 

 may be discovered ; perhaps that part which is washed 

 away may be as valuable as any part of it, for grains of 

 marl pulverised, and put in water, give to the water the 

 same appearance as that part does which is washed away, 

 and it may be ungranulated marl ; but I have estimated 

 the value of it by the greater or small proportion of these 

 grains found in it. VVe are yet ignorant of the part, or 

 what there is in marl which produces such great effects. I 

 have supposed that some marls act only from the sulphu- 

 reous acid which they contain, and that others act in a 

 double manner, by that and some other substance con- 

 tained therein. Some of us have an idea that those marls 

 which act the quickest on land are of shorter duration in 

 their effects ; but that is yet to be proved. Those iron 

 ores which cover the marl, that pulverise with the win- 

 ter, have so much of the marly nature in them, as to have 

 much the same effects on some lands as the marl. In 

 ipany places there is a stratum of fuller's earth over the 

 marl from one to four feet in thickness, and in one place 

 a stratum between two strata of marl. The effects of this 

 fuller's earth on some land are nearly equal to marl ; this 

 stratum of earth is commonly divided by separations, a few- 

 inches from each other, and falls when digging, into many 

 square irregular pieces, and these division lines are gene- 

 rally tinged with the oxide of iron ; this earth is generally 

 more or less sulphureous. Also, in many places over 

 the marl there is a stratum of a brown grey nature, very 

 tough and hard to dig, of from two to six feet in thick- 

 ness ; the owners of some marl-banks oblige the pur- 

 chasers to take that stuff with the marl, and to strangers 

 it may be put off as such ; it contains little or no marl, 

 and is of little worth. In some of the hard marl and gun* 

 H 



