No. 200.j 
155 
But this is momentary. When thoroughly kindled, it burns with less 
flame, yields a small proportion of blackish smoke, and sulphurous acid 
gas is evolved, though I cannot discover any pyrites. It burns for a 
long time, and emits a great body of heat. It leaves a very small pro- 
portion of light and grayish white ashes. Speaking of burning it, he 
says, " The attempt succeeded so well, that I cannot refrain from ex- 
pressing my opinion, that this variety of peat will answer as an excel- 
lent substitute for the best Liverpool coal."=^ 
During the surveys of the past season, I have collected specimens of 
peat from various localities. Some of them, now when dry, are com- 
pact enough to receive a slight polish, and have as great a specific gra- 
vity as bituminous coal, and would probably give out as much heat. 
Mluvions from Solution. 
Calcareous tufa is found near the spring which supplies the city of 
Hudson with water. It is a deposit from the water, which -contains 
carbonate of lime in solution. It encloses sticks, reeds, land shells, as 
helices, and in fact every substance with which it comes in contact when 
forming. It is an indurated stony mass. It is not extensive, and shows 
itself but little on the surface. It was pointed out to me by Mr. S. Ac 
Rowley, a young gentleman who has done much in developing the lo- 
cal geology of Hudson. Calcareous tufa is deposited abundantly from 
the waters of the New-Lebanon springs. 
Tufa is quite common in the limestone regions of Columbia and 
Dutchess counties. 
Calcareous concretions, such as stalactites and stalagmites, and con- 
creted carbonate of lime, of various forms, may be seen in the Spook- 
Hole, a cave near Barnegat. It is said to be hazardous to enter this cave 
far beyond its mouth, on account of the carbonic acid gas, which extin- 
guishes a lighted candle, and would destroy life in a short time. Lights 
burned well, however, when I visited it, as far as I could enter without 
creeping. 
Tufaceous marl occurs in New-Lebanon, on the farm of Mr. Tilden. 
It is deposited from the spring water, holding lime in solution. Some 
of this tufa is deposited in a solid form, enclosing leaves, &c. but most 
of it is in a finely divided form, which can be shovelled up, and is well 
adapted for a manure. Prof. Briggs, who examined this locality, states 
+ Am. Jour, of Science, I. p. 140. 
