CHAPTER, IF. 
NATURAL FERTILIZERS. 
Yen rocks of New Hampshire are largely granitic or feldspathic. In 
decomposition an abundance of potash is liberated, together with 
variable quantities of soda and lime. But our soils invariably show a 
small percentage of phosphates universally distributed. As crystals of 
apatite are uncommon, the question has often arisen in my mind, Whence 
is this salt derived? We cannot believe that enough animals have left 
their skeletons during the later periods, when the present soil was in 
the process of formation, to explain the commonness of this essential 
ingredient. If not of animal, it must have been of mineral origin. 
The statement has been made by prominent agriculturists, that our 
rocks generally contain phosphate of lime. One of the points aimed at 
in the microscopic study of our rocks has been a search for apatite, under 
the impression that the soil phosphate must exist in minute crystals, in- 
visible to the naked eye. Our researches have shown the presence of 
this mineral in rocks from every part of the state. This fact gives us 
confidence in the ability of our underlying formations to furnish from 
age to age a plentiful supply of this salt, so essential to the growth of 
crops. 
Part IV contains numerous incidental references to the localities of 
microscopic apatite. I will enumerate the instances there mentioned, 
presuming that they are much more abundant than are here indicated. 
It occurs in the porphyritic gneiss of Antrim, the ancient gneisses of 
