is the formation of soil, but once started, vegetation aids greatly in
the decomposition of rocks. Some forms of vegetation, as the lichens,
have apparently the faculty of growing on the bare surface of rocks, but
the higher order requires at least a little soil. The vegetation acts by
shading the surface and thus rendering the action of water more
effective, by mechanically separating the rock particles by means of its
penetrating roots and by the positive solvent action of the root juices.
The rootlets of plants in contact with limestone or marble dissolve
large portions of these substances, and while their action on more
refractory rocks is slower, it must be of considerable importance. The
organic matter introduced into the soil by vegetation also promotes
decay still further both directly and by the formation of acids of the
humic series. This matter also furnishes a considerable portion of
carbon dioxid which is carried by the water to assist in its solvent
action.
=44. Action of Earth-Worms.=—Of animal organisms those most active in
the formation of soil are earth-worms. The work of earth-worms has been
exhaustively studied by Darwin.[30] The worms not only modify the soil
by bringing to the surface portions of the subsoil, but also influence
its physical state by making it more porous and pulverulent. According
to Darwin the intestinal content of worms has an acid reaction, and this
has an effect on those portions of the soil passing through their
alimentary canal. The acids, which are formed in the upper part of the
digestive canal are neutralized by the carbonate of lime secreted by the
calciferous glands of the worms thus neutralizing the free acid and
changing the reaction to alkaline in the lower part of the canal. There
is a fair presumption that the acids of the worm are of a humic nature.
The worms further modify the composition of the soil by drawing leaves
and other organic matter into their holes, and leaving therein a portion
of such matter which is gradually converted into humus. Stockbridge[31]
gives a striking illustration of this process due to an experiment by
von Hensen. Darwin estimates that about eleven tons of organic matter
per acre are annually added to the soil in regions where worms abound. A
considerable portion of the ammonia in the soil at any given time may
also be due to the action of worms, as much as 0.18 per cent of this
substance having been found in their excrement. It is probable that
nearly the whole of the vegetable matter in the soil passes sooner or
later through the alimentary canals of these ceaseless soil builders,
and is converted into the form of humus.
=45. Action of Bacteria.=—The intimate relations which have been found
to subsist between certain minute organisms and the chemical reactions
which take place in the soil is a sufficient excuse for noting the
effect of other similar organisms in the formation of soils.
In addition to the usual forces active in decomposing rocks Müntz[32]
has described the effects of a nitrifying bacillus contributing to the
same purpose.
According to him the bare rock usually furnishes a purely mineral
environment where organisms cannot be developed unless they are able to
draw their nourishment directly from the air. Some nitrifying organisms
belong to this class. It has been shown that these bodies can be
developed by absorbing from the ambient atmosphere carbonate of ammonia
and vapors of alcohol, the presence of which has been determined in the
air. According to the observations of Winogradsky, they assimilate even
the carbon of the carbon dioxid just as vegetables do which contain
chlorophyl. Thus even in the denuded rocks of high mountains the
conditions for the development of all these inferior organisms exist. In
examining the particles produced by attrition, it is easily established
that they are uniformly covered by a layer of organic matter evidently
formed by microscopic vegetations. Thus we see, in the very first
products of attrition, appearing upon the rocky particles the
characteristic element of vegetable soil, viz., humus, the proportion of
which increases rapidly with the products of disaggregation collected at
the foot of declivities until finally they become covered with
chlorophyliferous plants.
In a similar manner the presence of nitrifying organisms has been noted
upon rocky particles received in sterilized tubes, and cultivated in an
appropriate environment where they soon produce nitrification. The naked
rocks of the Alps, the Pyrenees, the Auvergnes and the Vosges, comprise
mineralogical types of the most varied nature, _viz._, granite,
porphyry, gneiss, micaschist volcanic rocks and limestones and all these
have shown themselves to be covered with the nitrifying ferment. It is
known that below a certain temperature these organisms are not active;
their action upon the rock is, therefore, limited to the summer period.
During the cold season their life is suspended but they do not perish,
inasmuch as they have been found living and ready to resume all their
activity after an indefinite sleep on the ice of the glaciers where the
temperature is never elevated above zero.
The nitrifying ferment is exercised on a much larger scale in the normal
conditions of the lower levels where the rock is covered with earth.
This activity is not limited to the mass of rock but is continued upon
the fragments of the most diverse size scattered through the soil and it
gradually reduces them to a state of fine particles. It is therefore a
phenomenon of the widest extension.
The action of these micro-organisms according to Müntz is not confined
to the surface but extends to the most interior particles of the rocky
mass. Where, however, there is nothing of a nitrogenous nature, to
nitrify such an organism must live in a state of suspended animation.
When the extreme minuteness of these phenomena is considered there may
be a tendency to despise their importance, but their continuity and
their generality in the opinion of Müntz place them among the geologic
causes to which the crust of the earth owes a part of its actual
physiognomy and which particularly have contributed to the formation of
the deposits of the comminuted elements constituting arable soil.
The general action of nitrifying organisms in the soil, the nature of
these bodies, and the method of isolating and identifying them will be
fully discussed in another part of this work.
=46. Action of the Air.=—The air itself takes an active part in rock
decay. Wherever rocks are exposed to decay, there air is found or, at
least, the active principle of air, _viz._, oxygen. The air not only
penetrates to a great depth in the earth, but is also carried to much
greater depths by water which always holds a greater or less quantity of
air in solution. The oxygen of the air is thus brought into intimate
contact with the disintegrating materials and in a condition to assist
wherever possible in the decomposing processes.
The oxygen acts vigorously on the lower oxids of iron, converting them
into peroxids, and thus tends to produce decay.
There are other constituents of rocks which oxygen affects injuriously
and thus helps to their final breaking up. It is true that, as a rule,
the constituents of rocks are already oxidized to nearly as high a
degree as possible, and on these constituents of course the air would
have no effect. But on others, especially when helped by water with the
other substances it carries in solution, the air may greatly help in the
work of destruction.
In a general view, the action of the air in soil formation may be
regarded as of secondary importance, and to depend chiefly on the
oxidation of the lower to the higher basic forms. These processes, while
they seem of little value, have, nevertheless, been of considerable
importance in the production of that residue of rock disintegration
which constitutes the soil.
=47. Classification of Soils According to Deposition.=—In regard to
their deposition soils are divided into five classes:
1. Those which are formed from the decomposition of crystalline or
sedimentary rocks or of unconsolidated sedimentary material _in situ_.
2. Those which have been moved by water from the place of their original
formation and deposited by subsidence (bottom lands, alluvial soils,
lacustrine deposits, etc.).
3. Those which have been deposited as débris from moving masses of ice
(glacial drift).
4. Soils formed from volcanic ashes or from materials moved by the wind
and deposited in low places or in hills or ridges.
5. Those formed chiefly from the decay of vegetable matter, (tule, peat,
muck).
=48. Qualities of Soils.=—In respect of quality, soils have been
arbitrarily divided into many kinds. Some of the more important of these
divisions are as follows:
1. _Sand._ Soils consisting almost exclusively of sand.
2. _Sandy Loams._ Soils containing some humus and clay but an excess of
sand.
3. _Loams._ Soils inclining neither to sand nor clay and containing some
considerable portions of vegetable mold, being very pulverulent and
easily broken up into loose and porous masses.
4. _Clays._ Stiff soils in which the silicate of alumina and other fine
mineral particles are present in large quantity.
5. _Marls._ Deposits containing an unusual proportion of carbonate of
lime, with often some potash or phosphoric acid resulting from the
remains of sea-animals and plants.
6. _Alkaline._ Soils containing carbonate and sulfate of soda, or an
excess of these alkaline and other soluble mineral substances.
7. _Adobe._ A fine grained porous earth of peculiar properties
hereinafter described.
8. _Vegetable._ Soils containing much vegetable débris in an advanced
state of decomposition. When such matter predominates or exists in large
proportion in a soil the term tule, peat or muck is applied to it.
With the exception of numbers six, seven and eight these types of soil
are so well-known as to require no further description for analytical
purposes. The alkaline, adobe and vegetable soils on the contrary demand
further study.
=49. Alkaline Soils.=—The importance of a more extended notice of this
class of soils for analytical purposes is emphasized by their large
extent in the United States.
Chiefly through the researches of Hilgard attention has been called to
the true character of these soils which are found throughout a large
part of the Western United States and which are known by the common name
of alkali. The following description of the origin of these soils is
compiled chiefly from Hilgard’s papers on this subject. Wherever the
rain-fall is scanty, and especially where the rains do not come at any
one time with sufficient force to thoroughly saturate the soil and carry
down through the subsoil and off through the drainage waters the alkali
contained therein, favorable conditions exist for the production of the
alkaline soil mentioned above. The peculiar characteristic of this soil
is the efflorescence which occurs upon its surface and which is due to
the raising of soluble salts in the soil by the water rising through
capillary attraction and evaporating from the surface, leaving the salts
as an efflorescence.
Soils which contain a large amount of alkali are usually very rich in
mineral plant food, and if the excess of soluble salt could be removed,
these lands under favorable conditions of moisture would produce large
crops.
The formation of the alkali may be briefly described as follows: By the
decomposition of the native rocks, certain salts soluble in water are
formed. These salts in the present matter are chiefly sodium and
potassium sulfates, chlorids and carbonates. The salts of potash
together with those of lime are more tenaciously held by the soil than
the soluble salts of soda, and the result of this natural affinity of
the soil for soluble potash, lime and magnesian salts is seen in the
formation at the surface of the earth, by the process of evaporation
above described, of a crust of alkaline material which is chiefly
composed of the soluble salts of soda. In countries which have a
sufficient amount of rain-fall, these soluble salts are carried away
either by the surface drainage or by the percolation of water through
the soil, and the sodium chlorid is accumulated in this way in the
waters of the ocean. But where a sufficient amount of rain-fall does not
occur, these soluble salts carried down by each shower only to a certain
depth rise again on the evaporation of the water, reinforced by any
additional soluble material which may be found in the soil itself. The
three most important ingredients of the alkali of the lands referred to
are sodium chlorid, sulfate, and carbonate. When the latter salt,
namely, sodium carbonate, is present in predominant quantity, it gives
rise to what is popularly known as black alkali. This black color is due
to the dark colored solution which sodium carbonate makes with the
organic matters or humus of the soil. The black alkali is far more
injurious to growing vegetation than the white alkali composed chiefly
of sodium sulfate and chlorid.
This black alkali has been very successfully treated by Hilgard[33] by
the application of gypsum which reacting with the sodium carbonate
produces calcium carbonate and sodium sulfate, thus converting the black
into the white alkali and adding an ingredient in the shape of lime
carbonate to stiff soils which tends to make them more pulverulent and
easy of tillage.
This method of treatment, however, as can be easily seen, is only
palliative, the whole amount of the alkaline substances being still left
in the soil, only in a less injurious form.
The only perfect remedy for alkaline soils, as has been pointed out by
Hilgard, is in the introduction of underdrainage in connection with
irrigation. The partial irrigation of alkaline soils, affording enough
moisture to carry the alkali down to and perhaps partially through the
subsoil, can produce only a temporary alleviation of the difficulties
produced by the alkali. Subsequent evaporation may thus increase the
amount of surface incrustation. For this reason in many cases the
practice of irrigation without underdrainage may completely ruin an
otherwise fertile soil by slowly increasing the amount of alkali in the
soil by the total amount of the alkaline material added in the waters of
irrigation.
As Hilgard has pointed out, if a soil can be practically freed from
alkali by underdrainage connected with a thorough saturation by
irrigation, it may be centuries before the alkali will accumulate in
that soil again when ordinary irrigation only is practiced. It may thus
become possible to reclaim large extents of alkaline soil little by
little by treating them with an excess of irrigation water in connection
with thorough underdrainage. The composition of the alkali on the
surface of the soil due to the causes above set forth is thoroughly
illustrated by the analyses of Hilgard and Weber, which follow:
TABLE SHOWING COMPOSITION OF ALKALI SALTS IN SAN JOAQUIN VALLEY.
═════════════╤════════════════════════════════════════════
│ FRESNO COUNTY.
─────────────┼────────────────────────────────────────────
│ Sections 13 and 24 T. 14 S. R. 19 E., 4
│ miles S. W. from Fresno.
│
─────────────┼────────┬───────────────────────────────────
│ Alkali │ Alkali Spot, 1889.
│ soil, │
│ 1888. │
─────────────┼────────┼────────┬────────┬────────┬────────
│ „ │ 1 inch │ 18 │ 26 │ 42
│ │surface.│ inches │ inches │ inches
│ │ │ bel. │ bel. │hardpan.
│ │ │surface.│surface.│
─────────────┼────────┼────────┼────────┼────────┼────────
Soluble salts│ │ 0.76 │ 0.20 │ 0.18 │ 0.16
in 100 │ │ │ │ │
parts soil │ │ │ │ │
Potassium │ │ │ │ │
sulfate │ │ │ │ │
[D]Potassium │ │ │ │ │
nitrate │ │ │ │ │
Potassium │ │ │ │ │
carbonate │ │ │ │ │
(Saleratus)│ │ │ │ │
Sodium │ large │ small │ small │ very │ very
sulfate │ │ │ │ slight │ slight
(Glauber’s │ │ │ │ │
salt) │ │ │ │ │
Sodium │ very │ large │ small │ large │ large
carbonate │ slight │ │ │ │
(Sal-soda) │ │ │ │ │
Sodium │chiefly │moderate│chiefly │moderate│moderate
chlorid │ │ │ │ │
(Common │ │ │ │ │
salt) │ │ │ │ │
[D]Sodium │ │ │ │ │
phosphate │ │ │ │ │
Calcium │moderate│ small │ very │ very │ very
sulfate │ │ │ slight │ slight │ slight
(Gypsum) │ │ │ │ │
Magnesium │ │ │ │ │
sulfate │ │ │ │ │
(Epsom │ │ │ │ │
salt) │ │ │ │ │
Organic │ │ │ │ │
matter │ │ │ │ │
─────────────┴────────┴────────┴────────┴────────┴────────
═════════════╤══════════════════════════════════════════════════
│ FRESNO COUNTY.
─────────────┼────────────────┬────────────────┬───────┬────────
│ Miss Austin’s │ N.W. Cor. N ½ │Easton.│Emigr’nt
│ Ranch, Central │Sec. 20 T. 14 S.│ │ Ditch.
│ Colony. │ R. 21 E. │ │
─────────────┼───────┬────────┼───────┬────────┼───────┼────────
│Surface│Surface │Surface│Surface │ „ │ „
│ soil, │ soil, │ soil. │ soil. │ │
│No. 1. │ No. 2. │ │ │ │
─────────────┼───────┼────────┼───────┼────────┼───────┼────────
│ „ │ „ │ „ │ „ │ „ │ „
│ │ │ │ │ │
│ │ │ │ │ │
│ │ │ │ │ │
─────────────┼───────┼────────┼───────┼────────┼───────┼────────
Soluble salts│ 3.54 │ 1.90 │ 1.20 │ 2.69 │ │
in 100 │ │ │ │ │ │
parts soil │ │ │ │ │ │
Potassium │ small │moderate│ │ │ │
sulfate │ │ │ │ │ │
[D]Potassium │ │ small │ │ │ │
nitrate │ │ │ │ │ │
Potassium │ │ │ │ │ │
carbonate │ │ │ │ │ │
(Saleratus)│ │ │ │ │ │
Sodium │ large │ large │ much │moderate│ large │
sulfate │ │ │ │ │ │
(Glauber’s │ │ │ │ │ │
salt) │ │ │ │ │ │
Sodium │ small │chiefly │ small │ small │ │chiefly
carbonate │ │ │ │ │ │
(Sal-soda) │ │ │ │ │ │
Sodium │chiefly│ large │chiefly│chiefly │ large │ little
chlorid │ │ │ │ │ │
(Common │ │ │ │ │ │
salt) │ │ │ │ │ │
[D]Sodium │ │ │ │ │ │
phosphate │ │ │ │ │ │
Calcium │ small │moderate│ small │ small │ much │
sulfate │ │ │ │ │ │
(Gypsum) │ │ │ │ │ │
Magnesium │ │ small │ │ │ much │
sulfate │ │ │ │ │ │
(Epsom │ │ │ │ │ │
salt) │ │ │ │ │ │
Organic │ │ │ │ │ │
matter │ │ │ │ │ │
─────────────┴───────┴────────┴───────┴────────┴───────┴────────
Footnote D:
Very generally present, but not always in quantities sufficient for
determination.
═════════════════════╤═════════════════════════════════════════════════
│ TULARE COUNTY.
─────────────────────┼───────┬───────┬────────┬───────┬────────┬───────
│Goshen │Peopl’s│ Near │Visalia│Lemoore │Tulare
│ │ Ditch │ Lake │ │ │ Exp’t
│ │ │ Tulare │ │ │Station
─────────────────────┼───────┼───────┼────────┼───────┼────────┼───────
│Surf’ce│Alkali │Surf’ce │Surf’ce│ Alkali │Alkali
│ soil │ crust │ soil │ soil │ crust │ crust
─────────────────────┼───────┼───────┼────────┼───────┼────────┼───────
Soluble salts in 100 │ 1.40│ │ 0.83│ 1.26│ │
parts soil │ │ │ │ │ │
Potassium sulfate │ │ │ │ │ │ small
[E]Potassium nitrate │ │ │ │ │ │ small
Potassium carbonate │ │ │ │ 18.80│ │
(Saleratus) │ │ │ │ │ │
Sodium sulfate │ 44.24│ 1.22│31.30[F]│ 13.4│chiefly │ 32.8
(Glauber’s salt) │ │ │ │ │ │
Sodium carbonate │ 32.98│ 88.09│ 18.2│ 45.3│ │ 36.16
(Sal-soda) │ │ │ │ │ │
Sodium chlorid │ 16.74│ 1.00│ │ 4.4│ little │ 31.16
(Common salt) │ │ │ │ │ │
[E]Sodium phosphate │ 1.97│ │ 0.22│ 10.4│ │
Calcium sulfate │ │ │ │ │ little │
(Gypsum) │ │ │ │ │ │
Magnesium sulfate │ │ │ │ 8.1│moderate│
(Epsom salt) │ │ │ │ │ │
Organic matter │ 1.59│ 9.21│ 7.5│ │ │ 5.37
─────────────────────┴───────┴───────┴────────┴───────┴────────┴───────
═════════════╤════════════════════════════════════════════════════════
│ KERN COUNTY.
─────────────┼────────────────────────────────────────────────────────
│ Alkali crusts from the Smyrna artesian belt. Townships
│ 25 and 26 R. 23 E. W. S. W. from Delano, S. P. R. R.
─────────────┼─────┬────────┬────────┬────────┬─────┬─────┬─────┬─────
│No. 1│ No. 2 │ No. 3 │ No. 4 │No. 5│No. 6│No. 7│No. 8
│ │ │ │ │ │ │ │
─────────────┼─────┼────────┼────────┼────────┼─────┼─────┼─────┼─────
Soluble salts│ │ │ │ │ │ │ │
in 100 │ │ │ │ │ │ │ │
parts soil │ │ │ │ │ │ │ │
Potassium │ │ │ │ │ │ │ │
sulfate │ │ │ │ │ │ │ │
[E]Potassium │ │ │ │ │ │ │ │
nitrate │ │ │ │ │ │ │ │
Potassium │ │ │ │ │ │ │ │
carbonate │ │ │ │ │ │ │ │
(Saleratus)│ │ │ │ │ │ │ │
Sodium │small│moderate│moderate│moderate│large│small│small│small
sulfate │ │ │ │ │ │ │ │
(Glauber’s │ │ │ │ │ │ │ │
salt) │ │ │ │ │ │ │ │
Sodium │ │ │ │ │ │ │ │
carbonate │ │ │ │ │ │ │ │
(Sal-soda) │ │ │ │ │ │ │ │
Sodium │large│moderate│ large │ large │small│large│small│large
chlorid │ │ │ │ │ │ │ │
(Common │ │ │ │ │ │ │ │
salt) │ │ │ │ │ │ │ │
[E]Sodium │ │ │ │ │ │ │ │
phosphate │ │ │ │ │ │ │ │
Calcium │small│ small │ small │ small │small│small│small│small
sulfate │ │ │ │ │ │ │ │
(Gypsum) │ │ │ │ │ │ │ │
Magnesium │small│ small │ small │ small │small│small│small│small
sulfate │ │ │ │ │ │ │ │
(Epsom │ │ │ │ │ │ │ │
salt) │ │ │ │ │ │ │ │
Organic │ │ │ │ │ │ │ │
matter │ │ │ │ │ │ │ │
─────────────┴─────┴────────┴────────┴────────┴─────┴─────┴─────┴─────
═════════════╤══════════════
│ KERN COUNTY.
─────────────┼───────┬──────
│Summer.│ Kern
│ │Island
─────────────┼───────┼──────
│Alkali │Alkali
│ crust │crust
─────────────┼───────┼──────
Soluble salts│ │
in 100 │ │
parts soil │ │
Potassium │ │ 4.72
sulfate │ │
[E]Potassium │ │
nitrate │ │
Potassium │ │
carbonate │ │
(Saleratus)│ │
Sodium │ 19.20│ 70.61
sulfate │ │
(Glauber’s │ │
salt) │ │
Sodium │ │ 14.82
carbonate │ │
(Sal-soda) │ │
Sodium │ 37.14│ 4.13
chlorid │ │
(Common │ │
salt) │ │
[E]Sodium │ │
phosphate │ │
Calcium │ 0.96│ 0.08
sulfate │ │
(Gypsum) │ │
Magnesium │ 18.31│
sulfate │ │
(Epsom │ │
salt) │ │
Organic │ 20.87│
matter │ │
─────────────┴───────┴──────
Footnote F:
Common and Glauber’s salts.
=50. Adobe Soils.=—In many parts of the arid regions of this country
which can be recovered for agricultural purposes by irrigation the soil
has peculiar characteristics.
The name adobe as commonly used applies to both the sundried bricks of
the arid regions of the West and Southwest, and to the materials of
which they are composed. The material is described by Russell[34] as a
fine grained porous earth, varying in color through many shades of gray
and yellow, which crumbles between the fingers, but separates most
readily in a vertical direction. The coherency of the material is so
great that vertical scarps will stand for many years without forming a
noticeable talus slope.
_Distribution._—The area over which adobe forms a large part of the
surface has not been accurately mapped, but enough is known to indicate
that it is essentially co-extensive with the more arid portions of this
country. In a very general way it may be considered as being limited to
the region in which the mean annual rain-fall is less than twenty
inches. It forms the surface over large portions of Colorado, New
Mexico, Western Texas, Arizona, Southern California, Nevada, Utah,
Southern Oregon, Southern Idaho, and Wyoming. Adobe occurs also in
Mexico and may there reach a greater development than in the United
States, but observations concerning it south of the Rio Grande are
wanting.
In the United States it occurs from near the sea-level in Arizona, and
even below the sea-level in Southern California, up to an elevation of
at least six or eight thousand feet, along the eastern border of the
Rocky Mountains, and in the elevated valleys of New Mexico, Colorado,
and Wyoming. It occupies depressions of all sizes up to valleys having
an area of hundreds of square miles. Although occurring throughout the
arid region, it can be studied to best advantage in the drainless and
lakeless basins in Nevada, Utah, and Arizona.
_Composition._—When examined under the microscope, the adobe is seen to
be composed of irregular, unassorted flakes and grains, principally
quartz, but fragments of other minerals are also present. An exhaustive
microscopic study has not been made, but the samples examined from
widely-separated localities were very similar. The principal
characteristics observed were the extreme angularity of the particles
composing the deposit and the undecomposed condition of the various
minerals entering into its composition. It is to be inferred from this
that the material was not exposed even to a very moderate degree of
friction, and had not undergone subaerial decay before being deposited.
Adobe collected, at typical localities is so fine in texture that no
grit can be felt when it is rubbed between the fingers; in other
instances it contains angular rock fragments of appreciable size.
The composition of the material is illustrated by the following
analyses:
ANALYSES OF ADOBE.
BY L. G. EAKINS.
Constituents. No. 1. No. 2. No. 3. No. 4.
Sante Fe, New Fort Wingate, Humboldt, Salt Lake
Mexico. New Mexico. Nevada. City, Utah.
SiO₂ 66.69 26.67 44.64 19.24
Al₂O₃ 14.16 0.91 13.19 3.26
Fe₂O₃ 4.38 0.64 5.12 1.09
MnO 0.09 trace 0.13 trace
CaO 2.49 36.40 13.91 38.94
MgO 1.28 0.51 2.96 2.75
K₂O 1.21 trace 1.71 trace
Na₂O 0.67 trace 0.59 trace
CO₂ 0.77 25.84 8.55 29.57
P₂O₅ 0.29 0.75 0.94 0.23
SO₃ 0.41 0.82 0.64 0.53
Cl 0.34 0.07 0.14 0.11
H₂O 4.94 2.26 3.84 1.67
Organic matter 2.00 5.10 3.43 2.96
————— ————— ————— ——————
99.72 99.97 99.84 100.35