soils. 93 
1. Magnesian limestones are not necessarily injurious to vegetation; on the contrary, they 
may contribute to the fertility of soils. 
2. Magnesian limestones belonging to the class of dolomites, as those of the counties of 
Westchester, Dutchess, Putnam, &c. often injure vegetation, or impair the fertility of the soil, 
in consequence of that peculiarity in their structure by which they seem to resist the action 
of those agents which reduce many other limestones to a state of minute division. 
3. A lime containing magnesia may prove injurious if it be used within a short time after 
it has been burned; but if, after calcination, it is exposed to the air so as to allow the mag¬ 
nesia to be carbonated, it may then be employed with advantage in those cases where lime is 
indicated. 
In addition to the magnesian soils arising from the decomposition of magnesian limestones, 
we have also a magnesian soil produced by the breaking down of the serpentine and steatitic 
rocks which are found in various parts of the State. Richmond, Westchester, Putnam, Jef¬ 
ferson and St. Lawrence counties may be particularly mentioned as examples. And it is 
worthy of remark, as corroborating what has already been said concerning the influence of 
magnesia upon vegetation, that the soils upon the sides and bases of these serpentine ridges 
are equal in fertility to any found elsewhere. 
Although the ores of iron are very abundant in this State, what may be strictly termed 
Ferruginous Soils are not of common occurrence. This arises from the fact that the largest 
proportion of our ores are deposited in some rocky matrix, and hence they cannot be so easily 
reduced to that state of division which is necessary for their incorporation with the soil. Fer¬ 
ruginous soils are often found near the beds of hematite in Dutchess county, and also in those 
parts of Richmond, Westchester, Orange, and some of the northern and western counties 
where either bog iron ore or the lenticular iron ore abounds. It is not probable, however, 
that the oxide of iron, in the proportion in which it exists in these soils, produces any decided 
effects either beneficial or injurious. 
It is hardly necessary to remark, that soils are seldom characterized in so marked a manner 
as the above classification would seem to imply. They are mixed in various proportions, and 
in some cases it is not easy to determine to which of the classes they belong. Moreover, the 
nature of these soils is continually undergoing changes, in consequence of the various modes 
of culture to which they are subjected. This renders it exceedingly difficult to present ana¬ 
lyses of soils which shall be of practical utility. 
