ECONOMICAL GEOLOGY. 
209 
Phosphoric Acid, 9 cents per pound. 
Potash, 2 “ “ 
Sulphuric Acid, 4 “ “ 10 pounds. 
Lime, 2 “ 12 “ 
Magnesia, 2 “ “ 10 
Soda, 2 “ “ 5 “ 
The sulphuric acid exists as gypsum, (or is readily convertible into that 
form by the addition of lime.) With these data it is easy to arrive at an 
estimate of the value of a y marl whose analysis is known. And it will 
be found that the range of valuation per ton of the two latter classes of 
marls, Eocene and Miocene, is from 2 or 3, to 0 or 8 dollars. Thirty per 
cent, of lime, — a very common proportion, — gives a value at once of 
$1.00 per ton. And one per cent, of phosphoric acid gives $1.80: and 
some of the analyses show 2 and 3 and upwards, making, for this item alone, 
$3.60, $5.40 and more, per ton. According to the best information I 
can get, the marl does not cost generally more than 25 or 30 cents per 
ton for throwing out; — a common price is half a cent per bushel, which 
is but 10 cents per ton, — counting 20 bushels to the ton, as done in N. J. 
And it does not cost more generally to distribute it; put the cost at 50 
cents per ton in the field. (The marl is supposed to be found on the 
farm). If the marl be worth but $2.50 per ton, the profit is 500 per 
cent, on the outlay. If the results reach the half of this, or one-tenth 
even, it may be asked, what other farming operation in the state can 
compare with it in profitableness? But one of the most important con- 
siderations in estimating the value of a fertilizer has not been reckoned 
at all in the above count, viz : durability. While the effect of the high- 
priced commercial manures disappears with the season, or at most in two 
or three crops, an application of marl is good for a lifetime. Such is the 
testimony of all who have made the experiment among us. And similar 
results are attested elsewhere. Prof. Cook, of New Jersey, says of the 
use of marls there, “It gives lasting fertility to the soil. While all 
other fertilizers are exhausted and the soils become poor, I have never 
seen a field which has once been well marled that is now poor.” 
A nd another point worthy of mention is, that there are several other in- 
gredients in the above marls, besides those taken into the above estimates, 
that are often of great importance, as soluble silica, the oxides of iron and 
organic matter. 
From what has been said it is evident that, in the ease of a very large 
number of the marl beds of which anal} r ses are given, there is a large 
margin for transportation; the margin being the value, as estimated by 
