NATURAL FERTILIZERS. 95 
Westmoreland, Grafton, and Swanzey, various mica schists, the quartz 
schists of Portsmouth, the Huronian of Norwich and Hanover, the gab- 
bro of the White Mountains, the diabases of Bemis brook and Rye, the 
augite sienite of Jackson, the sienites of Chatham and Red hill, the dio- 
rites of Campton, Stewartstown, and Dixville, and the granite of Rye, 
Concord, Colebrook, Lightning mountain, Jackson falls, and the coarse 
veins carrying the valuable masses of mica and feldspar. It is found, 
also, in the porphyry of Waterville and Albany, and in the town of Pier- 
mont. 
The other natural fertilizers of importance are limestones and the vari- 
ous forms of peat. The first have been described already in the preced- 
ing chapter. It is astonishing that our farmers so entirely neglect the 
abundant supplies of limestone occurring in our midst, and either fail to 
procure this mineral, when required for their soil, or else purchase that 
which has been brought hundreds of miles. 
Only two beds of calcareous marl are known in the state,—at Hollis 
and Columbia. Both are limited in amount, while the substance itself 
is of excellent quality. 
Two and a half miles south-east of Colebrook village, in the north part 
of Columbia, is Lime pond. This pond is nearly a hundred rods long, 
and probably half as wide. Its bottom is covered with white calcareous 
marl, which has a depth in some places of 15 feet. On the east side of 
the pond there is also a buff-colored sedimentary deposit. 
The marl is formed by the accumulation of myriads of shells of the 
Cyclas and Planorbis, an abundance of which was everywhere found where 
the marl was covered with water, for the pond has been partially drained. 
Dr. Jackson supposed the neighboring peat swamp to be the most active 
agent in supplying the shell-fish with calcareous salts, from which they 
secrete the carbonate of lime of their shells. ‘On testing the water, it 
was found to be charged with crenate, apocrenate, and humate of lime, 
and it contains, also, a notable proportion of ammonia. In evaporating 
a portion of the water, a buff-colored precipitate subsides, which contains 
the above-mentioned organic acids, combined with lime and an excess of 
carbonate of lime, which was originally held in solution by carbonic acid 
as a bicarbonate.” 
Peat is the vegetable soil of bogs and swamps, and consists of the 
