KINDS OF SOILS. 155 
Clay or impalpable matters. Sand. 
Heavy clay contains 75—90° |, 10— 25°|, 
Clay loam oa 60—75 20— 40 
Loam 6. 40—60 40— 60 
Sandy loam“ 25—40 60— 75 
Light sandy loam contains 10—25 Ta— 90 
Sand . 0—10 90—100 
The percentage composition above given applies to 
the dry soil, and must be received with great, allowance, 
since the transition from fine sand to impalpable matter 
not physically distinguishable from clay, is an impercep- 
tible one, and therefore not well admitting of nice discrim- 
ination. 
It is furthermore not to be doubted that the difference 
between a clayey soil and a loamy soil depends more on 
the form and intimacy of admixture of the ingredients, 
than upon their relative proportions, so that a loam may 
exist which contains less sand than some clayey soils. 
Calcareous or Lime Soils are those in which carbonate 
of lime, is a predominating or characteristic ingredient. 
They are recognizable by effervescing vigorously when 
drenched with an acid. Strong vinegar answers for test- 
ing them. They are not uncommon in Europe, but in this 
country are comparatively rare. In the Northern and 
Middle States, calcareous soils scarcely occur to an extent 
worthy of mention. 
While lime soils exist containing 75°|, and more of car- 
bonate of lime, this ingredient is in general subordinate 
to sand and clay, and we have therefore caleareous sands, 
caleareous clays, or calcareous loams. 
Marls are mixtures of clay or clayey matters, with finely 
divided carbonate of lime, in something like equal propor- 
tions.* 
Peat or Swamp Muck is humus resulting from decayed 
* In New Jersey, green sand mari, or marl simply, is the name applied to the 
green sand employed as a fertilizer. Shed marl isa name designating nearly 
pure carbonate of lime found in swamps. 
