Report on methods for analysis of soils and ashes, for the American Association of official agricultural chemists

33 Kedzie are,
1 REPORT

METHODS, FOR

ANALYSIS OF SOILS AND ASHES

e
For THE AMERICAN ASSOCIATION OF OFFICIAL

AGRICULTURAL CHEMISTS.

By R? C. KEDZIE, REPORTER.

LANSING:
D. .D. THoRP, PRINTER AND BINDER.
1891.

6

the soil distilled water (ammonia-free) sufficient to moisten all the
soil, and let the whole stand undisturbed for half an hour, then
‘add more pure distilled water, and if the filtration is too slow use
the filter-pump till a liter of filtrate is secured. If the soil extract
is cloudy, filter through a plain filter. Each cubic centimeter of
filtrate contains the water-soluble materials of a gram of air-dry
soil.

9. Soluble solids. —Evaporate 100 c. c. to dryness on the water-
bath in a tared dish to determine the percentage of water-soluble
materials in the soil; each gram of residue representing a per
cent of such materials. Test this dry residue for nitrates by
pouring over it 10 c. c. of C.P. Hs SOs holding in solution three or
four milligrams of sulfate of brucia.

10. Chlorides.—Titrate 100 c. c. with standard decinormal argen-

tic nitrate with two drops of solution of K2CrO« as indicator.
Titrate in white porcelain dish and view the reaction’ through a
yellow glass plate of such tint as will eliminate the color of the
chromic solution. The reaction will then be sharply defined.
More than one part of soluble chlorides in one thousand of soil is
injurious to agricultural plants.

11. Sulfates.—Precipitate the soluble sulfates in 100 ¢. ec. with
BaCl. in presence of a few drops of HCl. and estimate the soluble
sulfates.

‘Reserve the rest of the water solution (8) for the estimation of
nitrates (26).

AcID-SOLUBLE MATERIALS.

In the following scheme for soil analysis it is recommended to
use the air-dry soil from the sample bottle for each separate in-
vestigation. A determination made -once for all of hygroscopic
moisture and of water of combination on a separate specimen of
air-dry soil will afford corrections for all the other samples used.
It is not desirable to ignite the soil before analysis, or to heat it so
as to change its chemical properties.

In an agricultural chemical analysis the object is to find the
kind and quantity of soil materials available for the growing plant.
The reserve or inactive materials are not objects of immediate
concern. Prof. Hilgard takes C.P. HCl. of specific gravity 1.115
as the solvent for soil materials, which may be supposed to fully
represent the solvent action that may be secured by water and
other solvents in the soil, and the action of the roots of growing

BY Wahi

FEB & 1916

plants or other corroding agents. The same acid and of the same
strength is here recommended, but with a modified form of using
the same. Instead of digesting the soil with this acid in a
covered beaker, with liability to continual variation of strength of
the acid, it is proposed to use the acid with constant strength
except so far as it may be neutralized by combination with the soil
minerals.

Instead of a porcelain beaker covered with a watch glass I pro-
pose for the soil digestion a four-ounce vial of Bohemian glass,
with a flat-topped ground glass stopper. The small steam bath
is a copper vesse! eight inches in diameter and five inches deep,
with vertical sides; the cover has four openings through which
the vials may readily pass down two and three-quarter inches to a
perforated false bottom upon which the vials rest, and the space
of two and a quarter inches below the false bottom serves for the
hot water chamber of the steam bath. Through the center of
the cover and of the false bottom a vertical tube, open at both
ends, extends nearly to the bottom of the vessel, for pouring in
water to replenish the waste; or a side tube near the bottom of
the hot water chamber may be connected with a water reservoir
to keep the water in the steam bath at a constant level. A Bun-
sen burner serves to heat up the steam bath and to keep the body
of the vials at the constant heat of boiling water. When such a
bath is set to work the digestion can go forward day and night
with very little care and attention. If the vials charged for diges-
tion are placed in the apparatus when cold and then heated up to
steam heat, no trouble is found from the vials breaking. When
the vials are properly charged and the escape of acid prevented,
thirty-six to forty hours of continuous digestion will be as effect-
ive as five days of intermittent digestion in a covered beaker.

12. Acid digestion of the soil_—Weigh five grams of the air-
dry soil into a four-ounce Bohemian vial, add 50. ¢. of C.P. HCL
sp. gr. 1.115, insert glass stopper, wire it securely, place in steam
bath and digest for thirty-six to forty hours at the temperature of
boiling water. Pour the contents of the vial into a small beaker,
wash out the vial with distilled water, add the washings to the
contents of the beaker, pour into this 2 c. c. of HNOs to peroxidize
the iron and oxidize organic matter, and evaporate the contents
of the beaker to complete dryness over the water bath. Cool the
beaker, add 10c. c. of C.P. HCL. sp. gr. 1.115 and 50c. ¢. of distilled
water and heat to near boiling. Filter from sand and silica,

ae Lae] %

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‘,

8

wash the filter with distilled water till the filtrate shows no reac-
tion with silver nitrate, and make the filtrate up to 500c. c. (Solu-
tion A), 100c. ¢. of which represents the soluble materials from one
gram of air-dry soil.

13. Sand and silica.—Dry the filter and insoluble residue from
A, transfer the residue to a tared platinum dish, burn the filter
and add its ash to the dish, heat the dish and contents, at first
gently to avoid spurting of silica, then intensely to destroy organic
matter, cool in desiccator and weigh. The merease of weight—
minus the filter ash—represents the sand and silica. Boil this
residue for fifteen minutes in 50c.c. of strong solution of sodic
sarbonate, add 100 c. c. of boiling water, filter while still hot, and
wash the filter and contents with boiling water till the sodic salts
are washed away. Dry the residue, burn the filter and add its
ash to the insoluble residue, heat this to redness, cool and weigh.
Deduct the ash of filter and enter the balance as SAND or INSOL-
UBLE srLicatrEs. The difference in weight between sand, and
sand and silica, enter as srnica. ‘This sand and silica will respect-
ively represent the amount of these materials in five grams of air-
dry soil, and these weights multiplied by twenty will give the per
cent respectively of sand and silica in such soil.

14. Ferric oxide and alumina.—To 200 ¢. c. of Solution A (in
an Erlenmeyer flask) add NU«HO to alkaline reaction (avoiding
excess), to precipitate ferric and aluminic oxides and phosphates.
Expel excess of ammonia by boiling, let it settle, decant the clear
solution through a filter; add to the flask 50c¢. c. of hot distilled
water, boil, settle and decant as before. After pouring off all the
clear solution possible, dissolve the residue with a few drops of
HCl. with heat, add just enough NH+HO to precipitate the
oxides. Wash by decantation with 50c.c. of distilled water, and
then transfer all the precipitate to the filter, and-wash with hot
distilled water till the filtrate becomes free from chlorides. (Save
the filtrate and washings, Solution B.) Dry the filter and pre-
cipitate in the air-bath at 110°, transfer the precipitate to a tared
platinum crucible, burn the filter and add the ash to the preecip-
itate, heat the whole red-hot, cool in desiccator and weigh. The
increase of weight—minus the ash of filter and the phosphoric
acid (found in a separate process)—represents the weight of the
ferric and aluminic oxides.

15. Ferric oxide.—Place the whole of the ignited oxides in an

to.

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As.

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9

Erlenmeyer flask (200 ¢. c. capacity), add 10 c. ec. of cone. H.S0,
and digest on steam bath till complete solution is effected; cool and
add 100c.c. of distilled water, a piece of amalgamated zinc and a
slip of platinum foil, cover with a watch glass and allow to stand
for twenty-four hours to reduce ferric to ferrous salt. When the
reduction is complete, as tested by transferring on a glass rod a
drop of the solution to a drop of ammonic-sulphocyanide on a
white porcelain surface, pour the solution at once into a beaker,
wash out the flask and transfer the washings to the beaker, taking
special pains to exclude any zinc, mercury or other reducing
agents, add 2c. c. of H2 SOs, make up the solution to 250c. c. with
pure recently-boiled water and titrate with standard solution of
permanganate for the ferric oxide present in two grams of air-dry
soil.

Preparation of standard permanganate solution.—Dissolve
3.156 grams of pure crystallized permanganate of potassium in
1,000 c.c. of distilled water at 16°, and preserve this in ground-glass —
stoppered bottle, shielded from the light. Standardize this solu-
tion with pure ferrous sulphate or ammonic-ferrous sulphate, or
oxalic acid, according to directions in Johnson’s Fresenius, § 112,
or Sutton’s Volumetric Analysis, § 30, and determine the equiva-
lent weight of Fe:Os for each c. c. of the permanganate solution.

The weight of ferric oxide deducted from ferric oxide and
alumina (14), with corrections for filter ash and phosphoric acid,
will give the weight of alumina in two grams of air-dry soil.

16. Manganese.—Concentrate the filtrate and washings from
B to 200c.c. If a qualitative test of the soil shows the presence
of manganese, add a few drops of bromine to the solution till the
color becomes orange, and keep the solution at the temperature of
60° for twenty-four hours. The manganese will separate as a
brownish hydrate, Mnz Oz (OH):2. Filter, wash the precipitate,
dry, and heat to redness, weigh and estimate as Mn, Os.

17. Lime.—If no manganese is precipitated, add to solution B,
or the filtrate and washings (from 16), 20. ¢. of a strong solution of
NH: Cl and 40c. c. of saturated solution of (NH:+)2 C2 O« to com-
pletely precipitate all the lime as oxalate and convert the mag-
nesia into soluble magnesic oxalate. Heat to boiling and let
stand for six hours till the calcic oxalate settles clear, decant the
clear solution onto a filter, pour 50c. c. of hot distilled water on the
precipitate and again decant the clear solution on the filter, trans-

2

/
10

fer the precipitate to the filter and wash it free from all traces of
oxalates and chlorides. Place the funnel over the mouth of a
500 c. c. Erlenmeyer flask, puncture the apex of the filter with a
glass rod, wash the oxalate into the flask with a jet of water, dis-
solve any adhering oxalate from the filter by dilute H, SO, (ten
per cent solution), wash the filter with a stream of distilled
water, add to the flask 20c.c. of Hs SOs, make the volume up to
300 c. c., heat to 70° and titrate with a standard solution of per-
manganate of such strength that one cubic centimeter will be
decolorized by .0063 grams of crystallized oxalic acid.. Each
ec. c. of permanganate solution will represent .0028 grams of
CaO.

18. Alternate method.—Transfer the washed and dried oxalate
to a tared platinum crucible, burn the filter on the crucible
cover, add the ash to the precipitate, cover this with cone.
H» SOs, heat gently to dryness, and then intensely to expel excess
of H. SOs, cool in desiccator, and weigh. Estimate the increase
of weight, minus filter ash, as calcium sulfate. Ca SO« X .41158
= Ca O.

19. Second alternate method.—Transfer the precipitate to a
tared platinum crucible, burn the filter and add this to the pre-
cipitate, heat the crucible and contents to low red heat to burn
the oxalate. Moisten the cooled mass with a saturated solution
of ammonic carbonate, dry and heat cautiously to low red heat,
cool and weigh. The increase of weight (minus filter ash) rep-
resents calcic carbonate, Ca COs K .56 = Ca O.

20. Magnesia.—Concentrate the filtrate and washings (from
17) to 200 c. e., place in half liter Erlenmeyer flask, add 30 c. ¢. of a
saturated solution of NazHPOs, and 20 ec. c. of cone. NHsHO, cork
the flask and shake violently at intervals of a few minutes till
crystals form, then set the flask in a cool place for twelve hours.
Filter off the clear liquid through a tared Gooch filter, transfer
the precipitate to the filter and wash with dilute ammonic hydrate
(1: 3) till the filtrate is free from phosphates; dry and ignite
the crucible, at first gently and then intensely, to form mag-
nesium pyrophosphate. The increase of weight X .36024—= MgO.
By using an Erlenmeyer flask free from scratches and marks,
and shaking violently instead of stirring with a glass rod, the
danger is almost entirely avoided of crystals adhering to the sides
of the vessel. But if crystals do adhere they are as readily removed

_—

11

by a rubber tipped glass rod from an Erlenmeyer flask as from a
beaker.

21. Sulfuric acid.—EKvaporate 200 c. c. of Solution A (12)
nearly to dryness on a water bath to expel excess of acid, then add
100 c. c. of distilled water; heat to boiling and add 10 ¢. ¢. of solu-
tion of BaCls, and continue the boiling for five minutes. When
the precipitate has settled, pour the clear liquid on a tared Gooch
filter, heat the precipitate with 50c. c. of boiling water, and trans-
fer the precipitate to the filter and wash with boiling water till the
filtrate is free from chlorides. Dry the filter and ignite strongly.
The increase in weight is barium sulfate, which X .34331 =
SO: in two grams of air-dry soil.

22. Phosphoric acid.—To the filtrate and washings from 21
add NH.4HO to alkaline reaction, then (NH«)2COs and a few
drops of (NH.)2 C2 Os to complete precipitation ; boil, settle and
decant the clear solution on a filter, add boiling water to the pre-
cipitate and again decant; finally bring the precipitate on the
filter and wash thoroughly. Dissolve the precipitate in HNOs,
and add molybdate of ammonium in excess to the solution. Keep
at temperature of 70° for six hours, and from the phospho-
molybdate of ammonium, estimate the phosphoric acid in the
usual way.

The material used in estimation of ferric oxide and alumina
(14) may also serve for a separate estimation of Ps Os. After
titration with permanganate, heat the solution to boiling and pre-
cipitate with NH.HO. Wash the precipitate by decantation,
dissolve in hot HNOs and precipitate by ammonic molybdate as
before, and estimate as pyrophosphate of magnesia. The pyro-
phosphate .6396 = Ps Os. In estimating the alumina in the
mixed precipitate of ferric and aluminic oxides and phosphates,
the Ps Os must be subtracted to obtain the final weight of alu-
mina. Thus, from the final weight of the precipitate, by
NH:+HO (14) subtract the filter ash, the ferric oxide as determined
by titration, then the P20s, and the remainder will be Als Os.

The solubility of the phosphates in the soil is intimately related
to their availability for growing crops. It has been assumed that
phosphates solwble in acetic acid are active and immediately
available for crops, and that soils containing acetic-soluble phos-
phates will not be benefited by the use of super-phosphates. To
determine the solubility of soil phosphates, boil ten grams of soil

bl

12

‘in 50c.¢, of strong acetic acid for fifteen minutes, filter, evaporate
the filtrate to dryness, ignite, dissolve the residue in HNOs with
heat, and test the solution with excess of molybdate of ammonium
at 70°.

23. Potash and soda.—Kyaporate the filtrate and washings
(from 22) to dryness, heat to low red heat to decompose oxalates
and expel ammonia salts, dissolve in 25c. c. of distilled water, filter
and wash the precipitate, add to the filtrate and washings 10 c. e.
of baryta water, and digest for an hour. Filter and wash precip-
itate, add ammonic carbonate to the filtrate to complete precipi-
tation of baryta, filter and wash this precipitate. Evaporate the
filtrate and washings in a tared platinum dish, gently ignite the
residue to expel ammonic salts, cool and weigh. The increase of
weight represents the chlorides of potassium and sodium in two
grams of air-dry soil.

Separate and estimate the potassium chloride by platinic chlor-
ide according to the official method of the Association of Agri-
cultural Chemists.

Subtract the weight of potassium chloride as thus found from
the weight of potassium chloride and sodium chloride. The differ-
ence represents sodium chloride.

Alternate method.—For alternate method for alkalies, use J.
Lawrence Smith’s method as given in Crook’s Select Methods,
second edition, pp. 28 to 40.

24. Other alkali metals.—The salts of lithium, czesium and
rubidium are occasionally found in very small amounts in soils.
The agricultural uses of these salts are still in question, and their
amount is too small to admit of quantitative estimation. A quali-
tative examination may be made by the spectroscope with the
water-soluble materials (8) evaporated to dryness and dissolved
with two or three drops of HCl. ‘Test by spectroscope with plat-
inum wire in Bunsen flame.

25. Nitrogen of the soil._—The combined nitrogen in the soil

and the state of combination in which it is held are subjects of

great importance to the agricultaral chemist. The nitrogen com-
pounds in the soil are usually placed in three classes:

1. The nitrogen combined with oxygen as nitrates or nitrites,
existing as soluble salts in the soil.

2. The nitrogen combined with hydrogen as ammonia, or
organic nitrogen easily convertible into ammonia. The ammonia

13

may exist as salts or be occluded by hydrated ferric or aluminic
oxides and organic matter in the soil.

3. The inert nitrogen of the soil or the humose nitrogen.

The nitrogen in the first and second classes is considered the
active nitrogen of the soil so far as plant food is concerned, while
the inert nitrogen is, for the time being, incapable of affording
sustenance to agricultural plants, and hence is properly placed in
a class by itself. But the exchanges between the first and second
classes are well known to chemists; the reduction of nitrates to
ammonia, and the oxidation of ammonia to nitrates are familiar
to agricultural chemists. It has also been a matter of discussion
which of these forms is best fitted to nourish plant life. They
seem to have equal agricultural activity, and their exchanges are
matters of almost daily occurrence. Why should they be separ-
ately estimated in an agricultural chemical analysis? . Why not
class them together as ACTIVE SOIL NITROGEN and estimate their
amount in one operation ?

26. Active soil nitrogen.—The material proposed for reducing
the nitrates to ammonia, and at the same time to bring ammonia
salts and organic nitrogen into condition for separation by distil-
lation, is sodium amalgam. Liquid sodium amalgam may be
readily prepared by placing 100 c. c. of mercury in a flask of
half liter capacity, covering the warmed mercury with melted
paraffine and dropping into the flask at short intervals metallic
sodium the size of a large pea (taking care that the violence of the
reaction does not, project the contents from the flask), till 6.75
grams of sodium have combined with the mercury. This amal-
gam contains one-half of one per cent of sodium, and may be
preserved indefinitely under the coverme of paraffine. The mer-
cury is easily recovered at the close of the operation, and nothing
of value is wasted except the sodium.

To estimate the active soil nitrogen, weigh fifty grams of air-
dry soil and place it ina clean mortar. ‘Take 200 c. c. of ammonia-
free distilled water, rub up the soil with a part of:the water to a
smooth paste, transfer this to a flask of one liter capacity, wash-
ing the last traces of the soil into the flask with the rest of the
water. Add 25c.c. of the liquid sodium amalgam, and shake the
flask so as to break the sodium amalgam into small globules dis-
tributed through the soil. Insert a stopper with a Kroonig valve
and set aside in a cool place for twenty-four hours. Pour into
the flask 50 c.c. of milk of lime and distil on a sand bath 100 e. e.

14

into a fiask containing 20 c. c. of decinormal sulfuric acid, and
titrate with decinormal soda solution, using dimethyl orange as
indicator. Estimate the nitrogen of the ammonia found as
active soil nitrogen.

If the ammonia produced is too small in amount to be readily
estimated volumetrically, determine the ammonia by Nessleriz-
ing the distillate.

’

27. Estimation of nitrates in the soil.—When it is desired ‘to
estimate separately the nitrates in the soil the following modifica-
tion of 26 may be used: Evaporate 100 c. ¢. of the soil extract (8)
to dryness on the water bath; dissolve the soluble portion of the
residue in 100c. ¢. of ammonia-free distilled water, filtering out any
insoluble residue, place the solution in a flask and add 10c. e. of
liquid sodium amalgam, insert stopper with Kroonig valve, set it
aside to digest in a cool place for twenty-four hours, add 50 c. c. of
milk of lime, distil and titrate as in 26, and estimate the nitrogen
as Ne Os.

Nesslerizing may be substituted for titration when the amount
of nitrates is small.

An approximate estimation of the amount of nitrates will be
of value in determining which method of estimation to use.
This may be done by evaporating a measured quantity of the soil
extract (8) say 5c. ¢., more or less, on a porcelain cover on a steam
bath or radiator, having first dissolved a minute fragment of pure
sulfate of brucia in the soil extract. When dry, pour over the
residue concentrated sulfuric acid free from nit¥ates, and observe
the color reactions produced.

If the nitrate (reckoned, as KNOs) left upon evaporating the
quantity of water taken does not exceed the two thousandths part
of a milligram, only a pink color will be developed by adding the
sulfuric acid; with the three thousandths part of a milligram, a
pink with faint reddish lines; with the four thousandths part, a
reddish color; with the five thousandths part, a red color.

sy increasing or diminishing the amount of soil,extract evap-
orated to secure a color reaction of a certain intensity, an approx-
imate estimate may be made of the amount of nitrates present.

Blank experiments to test the acid, and the brucine will be
required before confidence can be placed in such estimation.

28. Total nitrogen of soils.—The total nitrogen of soils may be
determined by the usual combustion with soda-lime, but this

ire) ;

15

process is often unsatisfactory, because of the large amount of
material required when the organic matter or humus is in
small amount.

A modification of the Kjeldahl method is more ‘easy to carry
out, and gives results equally satisfactory. Weigh out twenty
grams of air-dry soil, place this in a Kjeldahl flask and pour in
20. c. of sulfuric acid (free from ammonia) holding in solution one
gram of salicylic acid. (If the soil contains much lime or mag-
nesia in the form of carbonate, enough more sulfuric acid must
be added to secure a strongly acid condition of the contents of
the flask.) Add gradually two grams of zinc dust, shaking the
contents of the flask to secure intimate mixture. Place the flask
in a sand bath and heat till the acid boils, and maintain the boil-
ing for ten minutes. Add one gram of mercury and continue
the boiling for one hour, adding 10c. c. of sulfuric acid if the con-
tents of the flask are likely to become solid. Cool the flask and
wash out the soluble materials in the flask with 200 c. c. of pure
water, leaving the heavy earthy materials in the Kjeldahl flask.
Rinse the residue with 100 c. c. of water and add this to the first
washings. Place this soluble acid extract in a liter digestion
flask, add 35. c. of solution of potassium sulphide and shake the
flask to secure intimate mixture of the contents. Introduce a
few fragments of granulated zinc, pour in 75c. c. of saturated solu-
tion of caustic soda, connect the flask with a condenser and dis-
til 150 c. c. into a flask containing 20 c. c. of decinormal sulfuric
acid, and titrate with decinormal soda solution, using cochineal or
dimethyl orange as indicator.

Enter the nitrogen found in this operation as foal soil nitrogen.

The difference between the total soil nitrogen and the active
soil nitrogen will express the inert nitrogen of the soil.

29. Acid soils.—Soils of good agricultural quality are usually
neutral or slightly alkaline, but soils are found which give a deci-
dedly acid reaction when blue litmus paper is pressed upon the
moist surface. Swamp muck is often acid from the presence of
humic acid. Drying the muck removes the acid quality by
rendering the muck insoluble in water. If an acid soil becomes
neutral by drying, and the water filtered through the dried soil is
free from acidity, it is probable that the acid condition was caused
by an organic acid of the humus class. But if the acid condition .
persists after drying the soil, the cause is to be sought in sulfates
of some heavy metal, e. g., iron or copper, whose sulfates have
an acid reaction.

METHOD FOR ANALYSIS OF ASHES.

PREPARATION OF ASH.

The material before combustion must be thoroughly cleaned
from all foreign matters, especially from adhering soil: woods,
barks, roots, ete., by brashing and dusting, wiping with a moist
sponge, and finally by rubbing gently with a soft cotton cloth;
seeds by placing on a fine sieve and drenching them with distilled
water with constant shaking till the water runs off clear, and
finally rubbing the seeds between a soft cotton cloth. The ma-
terial should then be dried to constant weight at the temperature
of boiling water.

COMBUSTION OF ORGANIC SUBSTANCES.

The combustion should be carried on at a comparatively low
temperature, never reaching a full red heat, because of danger of
volatilizing alkaline chlorides, etc., nor ina strong draught of air
lest the lighter parts of the ash, e. g., silica, be carried away.

Combustion is best carried on in a flat platinum dish in a cast-
iron muffle, eighteen inches long, three and a half inches high,
and five inches wide at the bottom, the muffle resting on a fire-
brick inside the furnace to moderate the bottom heat, and the
fuel piled upon the top and sides of the muffle to burn the ma-
terial by surface heat.

When this ‘‘ Lawes & Gilbert muffle’’ is not at command the
ordinary assay furnace may be used by placing a fire-brick under
the muffle, placing the platinum dish and material for combus-
tion near the middle of the muffle, feeding the furnace with fuel
on the top and sides of the muffle so- as to maintain it at a low
red heat, and leaving the plug ¢ the muffle so as to allow a very
slow draught of air.

When no muffle of any kind is available the substance may be
burned to ash in a platinum dish properly guarded. In place of
‘a muffle use the sheet-iron dish commonly employed for a four-
inch sand-bath. Place the empty sheet-iron dish on an iron
tripod or other support, so that the gas flame from a Bunsen

Hy

burner may cover the whole bottom of the dish. On this dish
place a sheet-iron cone (of Russia iron), six inches high, three

‘ and a half inches in diameter at the bottom, and one inch at the
top. Such dish-and-cone-cover approximates the condition of a

muftie for materials placed inside the cone.
For the incineration use a flat-bottomed platinum dish, three
inches in diameter and one inch deep. Place the material for
, combustion in the platinum dish, put this in the empty sheet-
iron dish, place over the platinum dish and inside the sheet-iron
dish the sheet-iron cone, and heat the sheet-iron dish to low red
heat by gas flame. The cone should be made of Russia sheet-
iron to. avoid the danger of scales of iron rust falling into the
ash during combustion.

The cost of such combustion apparatus is small and the manip-
ulation simple, the platinum dish and contents will not be
heated to volatilizing alkaline chlorides, there will not be sufficient
draught of air to carry away any ash, yet the heat within the cone
will slowly and securely incinerate the contents of the dish.

With substances rich in silica and alkalies it is better to first
char the substance. Wash with distilled water to remove soluble
salts, then dry and incinerate the residue. Hvaporate the watery
extract and add this to the rest of the ash.

With substances rich in phosphates, e. g., seeds and animal
substances, char the material and remove salts by acetic acid,
decant the acetic solution, wash with distilled water, and then
complete the combustion. Add the acetic solution and washings
to the final ash, evaporate to dryness, and gently ignite the whole
to decompose the acetates. By this method seeds, etc., may be
incinerated in eight to ten hours.

In whatever way obtained the whole of the ash should be pul-
verized and intimately mixed before analysis: 7,

a a
ANALYSIS OF Woop ASHES.

Weigh out one hundred grams of air-dry ashes, and pass them
through a same sieve I trenty—meshes=to—the-ich} to separate
materials manifestly/ foreign, e. g., nails, broken glass and pot-
tery, pebbles, ete<7 and estimate the per cent of such accidental
materia ulverize any charcoal and semi-fused portions of
? remaining on the sieve, sift them and mix intimately with
the sifted ashes, and preserve in stoppered bottles for analysis.

c

1? Moisture.—Weigh out five grams of these ashes in a tared

wih rn sholer J willineks in demu

ce
o
4 C

18

platinum dish and heat to 110° C., in air bath to constant weight.
Cool in desiccator, and weigh. The loss of weight 20 = per
cent of moisture in the ash.

2° Carbon.—Heat this dried ash in platinum dish in the sheet-
iron ani cone apparatus described for incinerating organic sub-
stances till the ash is uniformly grayish-white and there is no
further loss of weight; weigh and determine this loss of weight,
which X 20 = per cent of charcoal in original ash.

3° Sand and silica.—Plaze this ignited ash in a four-ounce glass-
stoppered vial; measure out 50c. c. of HCl (sp. gr. 1.115) and pour
on the ash cautiously to prevent loss of ash by spurting, and
when all effervescence has ceased, add the balance of the acid,
insert glass stopper, wire it securely, and place in steam bath
(described under soil analysis) for two hours; empty the vial into
a platinum dish, wash the vial with distilled water, adding the
washings to the ash solution, and evaporate the whole to dryness
on water bath. A‘dd 10 c. c., dilute HCl and 50 ec. ec. of distilled
water to the contents of the platinum dish, transfer the contents
to a Schleicher & Schuell filter, wash with distilled water till the
last drops of filtrate are free from chlorides (when tested by solu-
tion of Ag NOs), dry and ignite the precipitate and filter. If
there are no grains of sand (revealed by grittiness when stirred
with a glass rod), subtract the ash of the filter from the weight.
of this residue and estimate the balance as silica. If sand is
present, boil the ignited and weighed residue in strong solution
of Na» COs to dissolve silica, wash by decantation to remove all
soda salts, dry and weigh the sand, the difference between the
weight of sand and silica + sand, will give the weight of silica,
and this X 20 = per cent of silica in the ash.

4° Phosphoric acid.—EKvaporate the acid, filtrate and washings
from silica to 100c. ¢., plac@this in an Erlenmeyer flask of 2506. c.
capacity, add NH: HO till nearly neutralized, then add 30c. c. of .
citro-magnesic*® mixture, then 30 c. c. of conc. NHsHO, cork

* The citro-magnesic mixture is prepared by“dissolving-two hundred
and seventy grams of citric acid in 850 c. c. of warm water and adding,
by degrees, twenty-seven grams of Mg CO;. When effervescence ceases
and the liquid is cool add 400 c. c. of dilute (1 to 10) ammonic hydrate,
and dilute the whole to a liter. Preserve in a well-stoppered bottle. In
the presence of a large excess, of NH, 20 c. c. of this mixture will insure
the precipitation of a decigram of P., Os even in the presence of ferric
and aluminic salts, unless their quantity is excessive.

See Sutton’s Volumetric Analysis, 5th edition, page 289.

| i) a
.

£9

the flask and shake the flask and contents violently at inter-
vals of a few minutes till crystallization is well established.
Set the flask in a cool place for four hours, then filter out
MgNH:PO; on a tared’ Gooch filter, wash the precipitate
with dilute ammonia (1 to 3), dry the Gooch filter, ignite,
at first gently and then intensely, to form pyrophosphate of
magnesia. ‘The increase of weight of the Gooch filter equals the
pyrophosphate of magnesia from five grams of ash. This multi-
plied by #2-7927.6396 5 Retry, will give the percentage
of Ps Oo HAR shes. ove v

In this method it is important to remove all the silica before
precipitating the phosphoric acid. It is also essential to use so
much of the citro-magnesic mixture as to prevent the precipita-
tion of phosphate of iron or alumina. If the addition of the
citro-magnesic mixture causes an immediate precipitation, the
precipitate is ferric or aluminic phosphate, and not enough of the
citro-magnesic mixture was used. In this case the process must
be renewed from the separation of silica, and the amount of
citro-magnesic mixture increased till no precipitate forms im-
mediately after its addition. In this case the addition of NH:HO
in excess will cause the complete precipitation of phosphate of
magnesia and ammonia after a time, while ferric and aluminic
salts will be held in solution.

Alternate method.—Molybdate of ammonia. The official method
for analysis of insoluble phosphates as prescribed for determina-
tion of total phosphoric acid is recommended as the alternate
method.

5° Carbonic acid.—Heat four or five grams of ash in the sheet-
iron and cone muffle till all charcoal is consumed; cool in a des-
iccator, weigh out two grams of ash and transfer to a Schroetter
alkalimeter. Fill one. chamber of the alkalimeter with HNO;
(sp. gr. 1.2) and the other with conc. H2SOs to dry the escap-
ing COs. Wipe the outside of the alkalimeter from every trace
of dust and moisture, and weigh the apparatus. Open the stop-
cock of the HNOs chamber and permit the acid to flow so as to
decompose the ash slowly, the CO2 bubbling up, a bubble ata
time, through the H:SO:. When effervescence ceases let the
whole of HNOs flow into the reservoir below, attach a CaCle tube
to the top of HNOs chamber, heat the alkalimeter on sand bath
to gentle ebullition and suck dry air through the apparatus till

20

COs is removed. Set aside the alkalimeter till it becomes cold,
and then weigh the apparatus. The loss of weight will repre-
sent the weight of CO» in two grams of ash.

Alternate method.—By Liebig’s potash bulbs. The usual
process of absorption by solution of KHO, weighing, etc.

6° Chlorine.—Pour out the nitric solution from the alkali-
meter upon a filter, wash out the last ppnaeme of the solution, pass
the soluble matters through the filter‘and wash the insoluble res-
idue with the water acidulttedAvith HNOs, To 1i8 filtrate add
solution of AgNOs to complete precipitation of tae chlorides,
boil and stir with a glass rod till the silver chloride separates in
flocks, let it settle, decant the clear liquid upon a filter, add
100 c. c. of water acidulated with HNOs and heat to boiling, again
decant the clear liquid upon the filter and wash the precipitate
with boiling distilled water; finally bring the precipitate upon
the filter and wash with distilled water till the filtrate gives no
reaction with dilute HCl. Dry the precipitate thoroughly and
transfer to a tared porcelain crucible with cover, ignite the filter
on the crucible cover, moisten the ash with a drop of HCl, evap-
orate the excess of acid, place the lid on the crucible and heat
the crucible till the silver chloride begins to melt around the
edges. Cool the crucible and weigh. The increase of weight
(minus the filter ash) multiplied by .1236 (i. e. pars X 50) will give
the per cent of chlorine in the ash.

This process should be carried on in the absence of direct sun-
|
light.

Alternate method.—Boil ten grams of ash in 400 c. c. of pure
water for half an hour; transfer all to a measuring flask of 500. ¢.
capacity, wash the beaker and add the washings to the flask,
cool, make up the volume to 500 c. c. and mix intimately. Filter
off through a dry filter 100. c., add a drop of solution of phenol-
phthalein, and neutralize with dilute HNOs till only a faint pink
color remains, add two drops of strong solution of Ka Cr Os and
titrate with standard decinormal solution of Ag NOs (16.956 grams
AgNOs @ 1000 c. c). Every. c. of the standard silver solution
equals .003546 grams of chlorine in two grams of ash, or ¢. ¢. X
.1773 = per cent of chlorine in ash.

In performing this titration, watch the reaction through a
plate of amber colored glass of such tint as will neutralize the

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y
¥
‘*
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21

color of potassic chromate. The reaction to form silver chro-
mate then becomes sharply defined.

The reliability of this method will depend upon the accuracy
with which neutralization by nitric acid has been made. The
least trace of free acid or alkaline carbonate will vitiate the results.

Second alternate method.—To 100 c. c. of the solution in the fore-
going method add HNOs to strong acid reaction, then solution
of AgNOs to complete precipitation, and then proceed as in the
first method for estimating chiorine.

These alternate methods are based on the assumption that
boiling water will dissolve all the chlorides present in wood ashes.

7° Sulfuric acid.—Place five grams of ash in a digestion vial.’
Measure out 50 c. c. of HCl. (sp. gr. 1.115) and cautiously pour
the acid on the ash till effervescence ceases, then pour in the rest
of the acid, place the glass stopper in place and wire it securely,
and place the vial in the digestion steam bath for two houre.
Pour the contents of the vial into a 250 c. c. measuring flask, wash
out the vial and add the washings to the flask, cool, make up to
250 ¢. c. with distilled water and mix intimately. Filter through a
dry filter 100 c. c. into a beaker, and evaporate on water bath till
excess of acid is expelled; add 100 ec. c. of distilled water, heat to
boiling temperature and precipitate with BaCl: in excess. Let it
stand for twelve hours ina warm place, then decant the clear
liquid through a filter, add 100c. c. of boiling water to the precipi-
tate, let it settle and then pour off the clear liquid through the
filter, repeating the process till the filtrate is free from chlorides;

finally transfer the precipitate to the filter, wash this with dis-

tilled water, dry the precipitate and transfer it to a tared cruci-
ble, separating the precipitate from the filter as completely as
possible, burn the filter separately, letting the ash fall into the
erucible, heat this to low redness, cool and weigh. Subtract the
filter ash from the increase in weight and multiply the remainder
by .34335 for SOs in two grams of ash. (Preserve the filtrate
and washings for 11°, Estimation of alkalies.)

8° Oxide of iron.—Filter 100 c. c. of the original acid solution
(for 7°) through a dry filter, nearly neutralize with ammonia
water, then add a gram of sodic acetate and acetic acid till the
odor of acetic acid is preceptible, boil to precipitate ferric phos-
phate, filter while hot and wash precipitate with boiling distilled
water till the filtrate is free from chlorides. Dissolve the ferric

22

precipitate on the filter with dilute H»SO« into a small Erlen-
meyer flask, wash the filtrate, dry and ignite the same and add
the ashes to the acid solution in the flask, reduce the ferric to
ferrous salt by amalgamated zinc or by a coil of magnesium wire,
till a drop of the solution gives no color, with NH« CyS. Pour
off the solution of ferrous salt into a beaker, rinse the flask and
add the rinsings to the beaker, add freshly-boiled distilled water
to make 200 c. c. of the solution, add 2 c.c. of sulfuric acid, heat to
70°, and titrate with standard solution of permanganate, and esti-
mate the iron as ferric oxide.

9° Lime.—Evaporate the filtrate and washings from ferric
phosphate (8°) to100 ¢c.c. To the hot solution add 20 c. c. of con-
centrated solution of ammonic chloride, and 40 ¢c. c. of saturated
solution of ammonic oxalate; boil the whole for ten minutes, and
then let it stand in a warm place for six hours; decant the clear
liquid upon a filter, wash the precipitate twice by decantation,
then bring the precipitate upon the filter and wash it free from
chlorides and oxalates, testing the washings by argentic nitrate.
Puncture the point of the filter with a glass rod, wash the calcic
oxalate into a 500 ec. ¢. flask by a stream by the wash bottle, dissolve
any oxalate adhering to the filter by dilute HeSO, (1:10), add
20 ce. ec. of HeSOs to the flask and make the volume to 300 ec. c.
with pure water, heat to 70° and titrate with standard solution of
permanganate in which each cubic centimeter of permanganate is
equivalent to .0063 grams of crystallized oxalic acid. Each cubie
centimeter of the permanganate solution used will be equivalent
to .0028 grams of Ca O.

Alternate method for lime.—Dry the washed precipitate of
calcie oxalate; transfer the oxalate to a tared crucible, burn the
filter on a platinum wire, letting the ashes fall into the crucible,
heat the crucible to low red heat, cool and moisten the contents
with a saturated solution of ammonic carbonate, dry and heat
carefully to low red heat to expel ammonic salt, cool and weigh.
Subtract the weight of filter ash, and estimate the increased
weight as Ca COs.

Second alternate method for lime.—Dry the washed precipitate
of calcic oxalate, transfer to a tared platinum crucible, burn the
filter and add the ash to the contents of the crucible. Overflow
the calcic oxalate with cone. HaSO , heat gently to dryness, and
then intensely to expel excess of H»SOs, cool in desiccator and

23

weigh. The increase of weight, minus filter ash, estimate as
ealcic sulfate, Ca SOs K .41158 = Ca O.

10° Magnesia.—Evaporate the filtrate and washings from calcic
oxalate to 200 c. c., pour into a clean and unscratched Erlenmeyer
flask of 500 c. c. capacity, add 30 ¢c. c. of strong solution of
(NH:)2HPOs and 50 c. c. of conc. ammonia hydrate, cork the flask
and shake violently at intervals of a few minutes till crystallization
is established, and then set aside for twelve hours in a cold place.
When precipitated in this way crystals will seldom adhere to the
sides of the flask, yet more perfect crystallization than’when stirred
with a glass rod. If crystals should form on the sides of the flask
they are as readily detached by a rubber-tipped rod as in a beaker.
Filter through a tared Gooch filter, wash the precipitate with
ammonic hydrate, diluted with distilled water (1 to 3), till
filtrate is free from phosphates (acidify a few drops of filtrate with
nitric acid and test with molybdate of ammonia). Dry the pre-
cipitate, ignite, at first very gently and then intensely, with blast
lamp, to convert 2 Mg NH« POs into Mg: P2 O7. Cool in desic-
cator and weigh. The increase of weight X .36024 = Mg O, in
two grams of air-dry soil.

11° Estimation of alkalies.*—Concentrate the filtrate and wash-
ings from (7°) to 100 ¢. ¢., add NH+ HO and (NH:)2C204 to com-
plete precipitation of barium and calcium, filter, wash the pre-
cipitate, evaporate the filtrate and washings to dryness in plat-
inum dish and ignite gently. Add to the residue concentrated solu-
tion of oxalate of ammonia, evaporate to dryness and ignite gently.
Dissolve residue in distilled water, filter from insoluble Mg O, acid-
ify the filtrate with HCl, and evaporate to dryness in a tared plat-
inum dish and ignite gently. The increase of weight represents
the chlorides of potassium and sodium in two grams of ash.
Separate and estimate potassium by PtCls, in the usual way,
and the sodium by difference.

*Test the filtrate from (7°) for lithia by the spectroscope with a loop
of platinum wire moistened with the filtrate, held in a colorless Bunsen
flame. The quantity of lithia is usually too small to be determined
gravimetrically, but it may be estimated by diluting the solution with
distilled water till the lithia line is on the point of disappearing from the
spectrum when a loop of clean platinum wire moistened with the solu-
tion is placed in the Bunsen flame. The wire must be clean for each
trial, and no concentration of the salt by repeatedly evaporating the
solution on the loop of wire without cleaning it. One part of Li Clin
450,000 parts of water will show the lithia line in the spectrum.

24 |

® 002 781 560 1

12? Manganese.—Manganese is not a usual constituent of wood
ashes. ‘Test the ashes for manganese by heating on platinum
foil over a colorless Bunsen flame half a gram of ashes with a
gram of sodic carbonate and a few grains of nitrate of potash.
The green manganate of soda in the fused portion as it cools
will show the presence of manganese.

To estimate manganese, dissolve two grams of ash in HCl.
Evaporate excess of acid over the water bath, pour the whole on
a filter and wash with distilled water to make 100 c¢. ¢., nearly neu-
tralize with sodic carbonate, and-then add half a gram of sodic
acetate and 20c. c. of strong bromine water and set the flask aside
in a warm place for twenty-four hours, or until the bromine has
nearly disappeared. Filter out the manganese oxide, wash thor-
oughly, transfer to tared crucible, heat gently, and then
intensely, and estimate the residue as Mns Os. Mns Os X .95013
= Mn O.

The manganese may be precipitated by passing a stream of
chlorine through the solution till fully saturated, instead of using
bromine water.

The ashes of mineral coal contain only a small amount of alka-
lies and phosphates, but a large amount of insoluble material,
clay, ete. Their yalue depends mostly upon the sulfate of lime
and phosphate present. They are often decomposed with diffi-
culty. They should be ground to a fine powder, and five grams

placed in the digestion vial, with 50 c. c. of HCl (specific gravity |

1.115) and digested in the steam bath for six hours, and the sol-
uble portion analyzed in the usual way.

The aluminic material is in so large proportion that it is better
to use the molybdic method for estimating phosphoric acid, after
eliminating soluble silica.

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