xt7nvx05xs69 https://exploreuk.uky.edu/dips/xt7nvx05xs69/data/mets.xml Peter, Robert, 1805-1894. 1877  books b96-12-34887778 English Stereotyped for the Survey by Major, Johnston & Barrett, Yeoman Press, : [Frankfort, Ky. : Contact the Special Collections Research Center for information regarding rights and use of this collection. Hemp Kentucky. Buckwheat Kentucky. Chemical examination of the ashes of the hemp and buckwheat plants  : with remarks on its bearing on hemp culture in Kentucky / by Robert Peter. text Chemical examination of the ashes of the hemp and buckwheat plants  : with remarks on its bearing on hemp culture in Kentucky / by Robert Peter. 1877 2002 true xt7nvx05xs69 section xt7nvx05xs69 











GEOLOGICAL SURVEY OF KENTUCKY.
         N. S. SHALER, DIRECTOR.



        CHEMICAL EXAMINATION

              'iF THE ASHES OF THE


HEMP AND BUCKWHEAT PLANTS,

           WITH REMARKS (IN ITS BEARING ON


HEMP CULTURE IN KENTUCKY.

    BY ROBERT PETER, M. D., ETC., ETC.,
           CHEMIST TO THE SURVEY.

      PART III. VOL. Il. SECOND SERIES.

                                   135 & 136

 This page in the original text is blank.

 







CHEMICAL EXAMINATION OF THE ASHES OF
  THE HEMP AND BUCKWHEAT PLANTS, &c.


  The hemp crop is of considerable importance in Kentucky
agriculture, more especially in the richer portion, called the
Blue Grass region, where the soil has been formed by the dis-
integration of the fissile layers of the lower Silurian lime-
stone-rich in the mineral elements of plant nourishment.
According to the State Auditor's report, the gross amount
of hemp fibre produced in our State was i8,98i,8i9 pounds
in 1872, and 21,375,306 pounds in the more productive, moist
season of 1873.
Of this latter quantity seventeen counties, situated wholly
or in part in the Blue Grass region, produced 21,194,445
pounds, and the five counties of Bourbon, Fayette, Jessamine,
Scott, and Woodford produced I 7,951,350 pounds. Mason
county, the next in this industry, having also raised 828,300
pounds. It is, therefore, evidently a crop which is believed to
be profitable only on our richest lands. The soil which best
suits it is the rich, pervious, and well-drained loam, well
charged with humus or the dark mould resulting from veg-
etable decomposition, such as results from the completely
decomposed sod of recently cleared woodland pastures, or
blue grass or clover ground, well plowed and made thorough-
ly fine and uniform in texture. Such land, in a favorable
season, has been known to produce as much as i,200 pounds
of hemp to the acre, and it will yield an average of about 8oo
pounds for ten to fifteen years in succession, if properly man-
aged, in ordinary seasons. As the price of hemp rarely falls
below one hundred dollars per ton of 2,240 pounds, and this
crop usually brings in cash, the great value of this industry is
evident.
                                                        13

 

4         CHEMICAL EXAMINATION OF THE ASHES OF

  The hemp plant, under favorable conditions, is of most rank
and luxuriant growth, attaining on our rich lands a height of
ten to fourteen feet in favorable seasons, even when Sown so
thick, as is the practice, that it is closely crowded, and so com-
pletely covers the ground that not a weed can grow amongst
it. It therefore requires a soil which can readily and quickly
furnish to it the mineral elements necessary to its rank and
rapid development, and at the same time furnish the large
supply of moisture it requires without losing that highly
porous condition and absorbing power which invites the pen-
etration of the gases and vapors of the atmosphere, on which
this plant is so greatly dependent for nourishment and growth.
  The well-drained loam of this Blue Grass region, which is
charged with black vegetable mould or humus, offers these con-
ditions; the humus not only having great power of absorption,
but containing in a soluble and available state the mineral
elements of plant nourishment, and, moreover, acting as a sol-
vent for those which are contained in the earthy constituents
of the soil itself. We can therefore readily understand why
the hemp plant thrives upon such land; but why so luxuriant
a growth can be maintained on the same surface for ten to
fifteen years in succession, without any material exhaustion of
the soil, is another question.
  The observing hemp farmer has long since arrived at a cor-
rect conclusion in this respect. He saw that while this most
luxuriant plant produced an immense green crop, and required
the richest soil to supply its rapid demand for nourishment
during its short season of growth (of four months only), yet
all its leaves and other green tissues, together with all that is
removed from it in the process of dew-rotting, in the ordinary
mode of hemp culture, are restored to the soil which produced
it, and nothing is sold and carried off from the land but the
cleaned hemp fibre, which, if well cleaned, contains very little
but atmospheric elements, the removal of which can therefore
cause but very little deterioration of the soil.
  Moreover, during a great part of the year the ground is
more or less shaded and protected, first by the growing plant,
'3.

 

THE HEMP AND BUCKWHEAT PLANTS, &C.



then by the roots left in the ground after cutting, which some-
what diminish the washing action of rains and improve it in
their gradual decay, as do also the leaves which fall and the
hemp when spread on the ground to dry, after being cut, and
lastly, when it is spread out upon it in the winter process of
dew-rotting, as it is called, during which all the readily decom-
posable parts of the plant are washed out and decomposed by
the rains and dews and the action of the air; enriching the
surface soil beneath.
Managed in this way, and commencing with suitable rich
land, the scientific observer understands, that although the
growing plants may temporarily draw heavily on the soil for
the mineral (earthy) ingredients necessary to their growth,
amongst the most important of which are potash and the
earthy phosphates, yet in the subsequent processes, the most
of these are returned to the ground again in the decay of the
leaves and other green parts, and in the soluble and decom-
posable matters which are leached out of the stems in the. pro-
cess of rotting; and that any small loss of these from the
arable surface which may occur from the sale of the hemp
fibre may be more than compensated by the action of the
tap-roots in bringing them up from the lower strata of the
ground. He understands further, that all the mineral ele-
ments thus restored, being left in organic combination in what
is termed the humus or vegetable mould which results from
this decay, are in a very soluble condition, and most available
for the quick nourishment of the subsequent crop.
If the hemp plant, instead of being dew-rotted on the
ground on which it had been grown, is entirely removed from
it and submitted to the process of water-rotting, the culture
becomes eminently exhausting to the land; mainly because
so much of the elements of fertility is necessarily carried off
in the water used. This was proved many years ago in rela-
tion to the flax crop of Ireland, in the chemical analyses of
the water in which the flax had been steeped, and of the plant
and the lint, by Dr. Kane; and experience to a certain extent
in this region, in the water-rotting of hemp, has given the
                                                         139



S

 

CHEMICAL EXAMINATION OF THE ASHES OF



same result. It is, perhaps, fortunate for our farmers, there.
fore, that this process, although several times proposed to
them, has never been received with much favor.
  The foregoing facts being of common experience, the writer
desired, by the chemical examination of the mineral or earthy
constituents of the hemp plant, as given in the ash, in different
periods and conditions of its growth, in different parts of the
plant, and the various stages of its preparation, to study more
fully the relations of this crop to the soil, and to understand,
if possible, the true reasons why it is not an exhausting pro-
duct when properly managed, as well as to learn the best con-
ditions for its successful culture.
  The first step in this investigation is to ascertain the aver-
age composition of the mineral ingredients of the entire hemp
plant as given by the chemical analysis of its ashes; and as
the works accessible to the writer give but very limited inform-
ation on the subject, he procured from his own farm, and sub-
mitted to this analysis, five different samples, produced in two
different seasons, grown under different conditions, and col-
lected in different stages of their growth.  The ashes of
these, obtained by careful incineration at a moderate heat,
were analyzed by the approved processes-several compara-
tive analyses of the same ash having been made to secure
greater accuracy-and the results are tabulated below in com-
parison with the average of two hemp-ash analyses published
in i865 by Professor Emil Wolff, of the Royal Academy of
Agriculture, at Hohenheim, Wirtemberg, which are repub-
lished in the Appendix, page 378, of As How Crops Grow," by
S. W. Johnson.
  The samples examined may be described as follows:
  Sample A. Entire hemp plants, including roots, leaves, &c.;
collected on September 4th, i874, when fully mature and
ready for cutting; grown on somewhat elevated, very rich
ground, the second year only from the broken up blue grass
sod of woodland pasture, which had not been previously
cleared or cultivated within the memory of the present race,
40



6

 

THE HEMP AND BUCKWHEAT PLANTS, &C.



but which had been the site of a large circular earth-work
by the ancient mound-builders, and which seemed to have
been enriched by a long residence upon it of these prehistoric
people. The sample, notwithstanding the great fertility of
the land, was very small, in consequence of a continued drought
Which prevailed during tha season of its growth, it not being
more than six to seven feet in height.
Samiple B. Mature hemp plants, taken as it is usually cut, the
roots and a small portion of the stems being left in the ground,
and having only the top leaves, the others having fallen; col-
lected September, 1873; grown on the field described above
in a very moist and favorable season, so that it was very tall
and large stemmed.   The samples were about twelve feet
high. Some hemp plants this year attained a height of four-
teen feet.
Sample C. Six hemp plants entire, leaves, roots, and all;
collected, before full maturity, on July 27th, i874, from the
same rich field, in the very dry season. The plants were about
six feet high, and were in full leaf and in flower.
Sample D. Entire hemp plants, including roots, leaves, and
immature seeds; grown on the experimental field selected by
my son, Benj. D. Peter,+ for practical experiments in hemp
culture. This ground had been long in cultivation-at least
fifty years. This sample was grown on lot 3, to which abcn2t
200 pounds of plaster had been applied early in the growing
season. The sample was collected on September 8th, i874.
The plants were quite small, not more than from five to six
feet high, in consequence of the continued drought of this
season and the condition of the land.
Samiple E. Similar to sample D; grown on the neighboring
lot 4, of this experimental field, under similar conditions, ex-
cept that no plasier or any other fertilizer was applied to this lot.
A part of this lot 4, however, where a fence row formerly
stood, happened to be somewhat richer than any part of this
'Fully described in Collins' History of Kentucky.
tSee Prof. N. S. Shaler's Report.
                                                          la1



7

 

CHEMICAL EXAMINATION OF THE ASHES OF



or the plastered lot, as shown by the greater luxuriance of the
growth of the hemp in that part.
  F. The average of the analyses of the ashes of two entire
hemp plants as given by Prof. Emil Wolff, as above stated.
  In this table, as well as in the following ones, the carbonic
acid of the ash'is excluded in the calculations, for more com-
plete comparison of the proportions of the essential mineral
ingredients of the ash.

TABLE I. A. OF THE CHEMICAL COMPOSITION OF THE ASH OF THE
ENTIRE HEMP PLANT, CALCULATED IN loo PARTS OF THE ASH, WITH
EXCLUSION OF CARBONIC ACID.

                           A.    B.     C.     D.  -E.      F.

Lime.38.482 31.299 4.8.689                   5.623 45.263   43.4
Magnesia.,,,,,,,,,,       8.558 6.o07  6.445  8.576 11.225   9.6
Potash.37.475 43.739 29.118                  23.519 23.933   18.3
Soda.378                         1.438 X.280   .472    009  3.2
P'hosphoricacid.8.667 14.164            10.384 11.721 13.233   ii.6
Sulphuric acid.. .. .. . 2.272  1.622   .940  1.472  1.445   2.8
Chlorine... .. .         .984    .522   .640   .301  .273    2.5
Silica..... . .. .. .. .  3.181  1.199 2.749  3.316 3.342    7.6

Per cent. of earthy phosphates. . i8.286  29.773 21.692 28.460 27-427 .   ,

Per cent. of ash to the air-dried
plants, carbonic acid excluded . 4.223  2.563  5.055  4.126  4.203  4.6

Per centage of ash, carbonic acid
included.               5.......   , 5569  3357  6.754 5. 288 5.346

  This table shows some notable differences in the ash pro-
portions and composition. For example, sample B, grown in
the moist season, as compared with the others grown during
the drought, gave a smaller ash per centage to the dried
plants; its ash contains smaller proportions of lime, magnesia.
and silica, and larger proportions of potash, soda, and phos-
phoric acid.
  The immature sample C, gathered in July, as compared
with the other samples (A, D, and E) of the same dry season,
which were gathered in September, shows a larger per cent-
age of ash to the dried plants.
142

 

THE HEMP AND BUCKWHEAT PLANTS, &C.



  The samples D and E, grown on the old land, while they
give about the same average of ash to the dried plants, show
a smaller proportion of potash.
  Not much importance is attached to the proportion of silica,
which is evidently stated much too high in the analyses quoted
by Wolff. The hemp plant, being somewhat viscid on its ex-
terior, always has more or less fine silicious dust adhering to
it, derived from the soil, which cannot be removed by wash-
ing the plants. This the writer attempted to exclude, in his
analyses, by dissolving the ash in diluted acid (nitric or chloro-
hydric), and excluding all that remained undissolved as most
probably fine earth accidentally adhering to the plant. This
may, in some cases, be a slight cause of error, but probably
not so great as the retention and analysis of the adhering
fine dirt with the plant ash, which seems to have been done
in the analyses quoted by Wolff. For the same reason the
alumina and iron oxide were also excluded.
  The real significance of these differences of proportion and
composition of these ashes can better be seen where. the com-
parison is made with the proportions of the dried plants them-
selves to the several ingredients of the ash, as given in the
following table:

TABLE I. B. OF THE QUANTITIES OF THE ASH INGREDIENTS IN too PARTS
   OF THE AIR-DRIED HEMP PLANTS, CARBONIC ACID EXCLUDED.

                          A.    B.     C.     D.     E.    F.'

lime... .. . .. .. . ..  1.624  0.802  2.461  2.103 x.968    1.74
Magnesia.. ...     ..   .361     .154   .312   .356   .475    .30
Potash........ . .   .   1.582  1.121  1.472   .977  1.012    .74
Soda.oi.......................06 .037   .o65   .019 a trace.  .1:
Phosphoric acid.... .. ..   .366   .363   .525   .488  .560     .47
Sulphuric acid....... .      0..o6  .042   .o47   .o6z   .06i    .so
Chlorine.... .. . .. ..   .041   .013   .022   .012   .01l    .10
Silica.... .. .. . .. ..   .134   .031   .139   .135   .141    .30

Per cent. of earthy phosphates  .  .768  .763  1.103  i. l82  1150 . .  

PI'er cent. of ash to dried plants. . 4.223  2.563  5 055' 4. 26  4.203  4.00

o SI Woff'. IWM-, " How Crop. G.ow," P-a 383. Caltd to the dried pla.
                                                              143



9

 
10      CHEMICAL EXAMINATION OF THE ASHES OF



  This table shows, that while the smallest proportion of min-
eral or ash ingredients, to the dried plants, was given in the
season when the hemp had a luxuriant growth because of the
regular supply of moisture, the difference was occasioned
mainly by the greater quantities of lime, magnesia, and silica
in the plants of the dry season, and not by any material
variations in the proportions of the alkalies or phosphoric
acid.
  It is well known that the external tissues of all growing
plants become more or less charged with earthy salts, espe-
cially carbonates of lime and magnesia with some phosphates,
which have been carried from the soil to their surfaces in solu-
tion in water containing carbonic acid (which is in all the water
of the soil) and left there in a form insoluble in water upon
the escape of that acid and the evaporation of the water which
brought them up.   As all the moisture of the fertile earth
contains this solution, which is drawn up and evaporated from
the general surfaces of the plants exposed to the air, it can
readily be seen, that because of the greater evaporation and
the more concentrated nature of the soil solution, in the dry
season, there must necessarily be a larger accumulation of this
surface deposit in the dry than in the moist or wet season, when
evaporation is measurably checked. For the same reason the
ash per centage of the leaves and bark of plants is greater than
that of the interior parts, and that of the leaves of deciduous
plants greater than that of the leaves of evergreens, which
give off less water by evaporation.
  The effect of this evaporation has very justly been com-
pared to the deposit of the limestone crust in the steam-
boiler and the formation of stalactites in caves; and this
irregular increase of the ash per centage causes many appa-
rent discrepancies in the mineral ingredients of plants, and
increases the difficulties in the chemical study of plant nourish-
ment; for while it is generally admitted as fully demonstrated,
that certain mineral ingredients; to be found in the ashes of all
vegetables, are essentially necessary to their growth, it must
be acknowledged that some or some portion of these ingredi-
144

 

THE HEMP AND BUCKWHEAT PLANTS, &C.



ents are of no more significance than the incrustation in the
steam-boiler; being mere accidental deposits on the surface,
the result of the escape and evaporation of the agents, water
and carbonic acid, which held them in solution in the sap of
the plants and in the water of the soil.
In the same manner may we explain the influence of a dry
season in increasing the fertility of the surface of the soil;
the soil solution, on the evaporation of the water, leaving its
dissolved salts and other ingredients upon the surface; so
that seasons of long drought are usually followed by others
of great productiveness when there is sufficient moisture.
The larger ash per centage of sample C is mainly due to
this cause; the leaves not having fallen, which yield a very
large proportion of ash.
The ashes of samples D and E, grown on the old land in
the very dry season, while not differing much in their general
weight-proportion to the dried plants, show more lime and
less alkalies than that of the hemp grown on the richer land.
For some reason not immediately apparent, perhaps because
of a previous buckwheat crop, they gave rather more than the
average quantity of earthy phosphates.
  In the usual mode of management of the hemp crop the
leaves mostly fall on the ground on which it is grown. A
large proportion of them drop before the hemp is cut, more
fall when it is spread on the ground to dry after cutting, and
when it is taken up to be stacked. It would be well, doubt-
less, to beat off, in this process, all the leaves that can thus
be separated, so that they may be more regularly distributed
over the soil than if thrashed off when stacking it. It is also
the general practice now to cut the hemp as nearly as possible
to the surface of the ground, and leave the roots, with a few
inches of the stem attached, to rot in the soil.
  In order to ascertain the relative fertilizing influence of the
leaves and roots, three hemp plants were collected, July 25th,
1864, in the dry season, from the rich field above described.
These, one male and two female plants, were about six to
    VOL IL-0o                                              14S



I I

 

12        CHEMICAL EXAMINATION OF THE ASHES OF

seven feet high. The leaves, stems, and roots, carefully sep-
arated and thoroughly air-dried, weighed as follows:
The leaves weighed:l 23.916 grammes, equal to about 30. per cent. of the whole plant
TAh roots      7 433                    9.3
The stems     48.430                   6o.7
  These were separately incinerated and their ashes analyzed,
with the following results:

TABLE II. OF TIEl RELATIVE ASH INGREDIENTS OF THE LEAVES, ROT.,
       AND STENIs OF THE HEMP, CARBONIC ACID EXCLUDED.

          TH E LEAVES.            THlE STEMS.  THE ROOTS.
                         Ine p'o ls In ooeps  tIn loo p ts In Roop ts Ie  p  nlox Is x,
                                of dosS  efool..of drid  ofo as. of d so
                                 laeem5 oots.  lm.

Lime...... . . .  . ... 48.819 4-992    23.371 0.949 20.368   0.713
Magnesia.                  5.726  .585   5.803  .194  8.297    .291
Potash.       .           27955 2.8581 49-599   1.659 52.233  1.829
Soda..............236             .024  
Phosphoric acid.9.264              .947  13.374   .447 15.164   .531
Sulphuric amid..... .... 2.209      .226   1.215   .040  1X344   .047
Chlorine..... . .. . .. ..171           .017    .576  .019   .405    .014
Silica.... .. . .. .. . . 5.620   .575   1.o62   .035 2.189    .077
      ___                                  IlJ  l 7
Per cent. of phosphates . ig.i6.  .95  28.158  0.942 26.885  0.949

Per cent. of ash  ..       . . . 10.225...     346 3           .50 2

  By examination of the above table it is to be seen, that the
leaves of the flowering hemp contain more of the essential
mineral ingredients of the soil than all the other parts of
the plant; constituting, as they do, about 30 per cent. of the
whole plant in the air-dried state, and yielding IO.225 per cent.
of their weight of ash, the carbonic acid being excluded; while
the stems and roots, which together form the remaining 70 per
cent. of the weight of the plant, give an average of less than
3.5 per cent. of ash.
  Nor is this great excess of the ash proportion in the leaves
due entirely to the influence of the greater evaporation which
takes place on their surfaces, causing a deposit or incrustation
of lime and magnesia salts and silica of the nature of stalag-
mites; for we see that whilst the amount of silica in the leaves
is nearly fourteen times greater than that in the stems, and
146

 

THE HEMP AND BUCKWHEAT PLANTS, &C.



more than seven times greater than in the roots; the lime
more than five times as great as that in the stems, and seven
times more than in the roots; the magnesia three times more
than that in the stems, and twice as much as that in the roots;
the p/osp/wric acid and phosphates and the alkalies are in nearly
double proportion in the leaves also, and the sulphuric acid
five times greater in them than in the stems, and about four
times greater than in the roots. So that whilst the leaves,
when in their fully matured state or when they naturally fall,
may possibly contain scarcely any but the less soluble salts
which may be left in their tissues on the evaporation of the
carbonated water which held them in solution in the sap, they
contain, when in the growing, active condition, like all other
green herbage, a very large proportion of salts of potash,
and of all the mineral elements of plant nourishment, and
hence may greatly enrich the soil on which they decay. It is
obviously to the interest of the hemp farmer, therefore, so to
manage as to spread them as regularly as possible over his
hemp ground.
The dried hemp plants are allowed to remain in the stack
until the cool season of early winter, when they are generally
spread out evenly upon the same ground on which they had
been grown, to undergo the process of dew-rotting. The
hemp is permitted to remain on the ground until, by the action
of the atmospheric waters and other agencies, it has become
so far decomposed that all its soluble parts and soft tissues
are removed and washed into the soil beneath or dissipated in
the air, and the tough hemp fibre can be easily separated from
the more woody portion of the stems. It is then taken up,
braked" out, and the clean merchantable hemp fibre sep-
arated from the "hemp-herds," or "hemp siaves "-the broken
fragments of the woody parts of the stems-which are usually
burnt up by the hemp-brakers on the spots where they fall
near their hemp-brakes.
In order to study the changes which occur in the mineral
constituents of the hemp during this process of dew-rotting,
samples of dew-rotted hemp plants, ready for the brake, were
                                                         147



13

 


14        CHEMICAL EXAMINATION OF THE ASHES OF

gathered, in December, from the two lots of the experimental
field above mentioned, of the crop of the dry season of 1874.
These were thoroughly air-dried, incinerated, and their ash
submitted to analysis, with the following results:

TABLE III. OF THE ASH ANALYSES OF DEW-ROTrED HEMP PLANT,
                  CARBONIC ACID, &c., EXCLUDED.

                                 (D) sAMFL; FRcOM LO 3.  (E) SA LE FRO3  LOT 4.
                                 PL.ANTS-ID. (sfa D.)  NO TErErD.  (SEE .a)

                                 In ooparts Of In impt of ID zoopatofntsspO nloaretof
                                   ash.  dried  h h.   di  hemp-,
                                         plants.         plants.

Lime.................             68.846   1.235   63.651   0.942
Magnesia...........        .. .    8.335    .149   8.343     .24
Potash............                 5.716    .102   5.682     .084
Soda.       .        ..    . ..    .429     .oo8    .760     .012
Phosphoric aci. .13.979                     .251   15.713    .233
Sulphuric acid......... . . . 965             .017    1.552    .023
Chlorine.     . .. . .. .. . .. .           .      4 .042    .001
Silica   .        .                 .68     .030    4.257     .o63

Per centage of earthy phosphates . 27.144  .487  29.920  .443


Per cent, of ash to the dried rotted hemp .  .  793 .....  1.480

  On comparing these results with those given in tables I. A.
and I. B., in the columns D and E, where the results of the
analyses of the ashes of this same growth of hemp are given
in the unrolled state, it will be seen that a great diminution
has taken place in the amount and proportions of the ash and
its several ingredients.
  To exhibit this diminution of the ash ingredients, which
takes place in the ordinary process of dew-rotting, we place
the averages from table I. B. and the above table side by side
in
148

 



THE HEMP AND BUCKWHEAT PLANTS, &C.



TABLE IV. COMPARATIVE VIEW OF THE ASH OF THE UNROTTED AND
THE DEW-ROTTED HEMP PLANTS, CARBONIC ACID BEING EXCLUDED.
                              Ave     Aeof0Arergf D
                              an. Un- and E. D- Prpoio emovd by de-
                              ted hemp  rted heamp  rtting.
                              pLant.  pL-ns

Lime.2.o36                               1.o89 About one half.
Magnesia         ..41S                    .136 Nearly two thirds.
Potash          ..995                     .093 More than nine tenths.
Sa..................               19     .010 About one half.
Phosphoric acid.524                          .242 More than one half.
Sulphuric acid..                   o6     .o0o About two thirds.
Chlorine..01                               .001 Ten elevenths.
Silica.. . . .. . .. .. . .. .. . 138       .047 Nearly two thirds.

Per cent. of earthy phosphates . . . . ..  s. i66  .465 More than one half.

Per cent. of ash to the dried plants . . .  4.165  1.636 More than one hai.

  When we also take into consideration the fact that the dried
hemp plants lose at least one third of their weight in the dew-
rotting, we can judge how large a proportion of the essential
mineral ingredients are restored to the soil in this process.
  The above table also shows us that the more soluble ingre-
dients, such as the alkalies, &c., are removed from the plants
in the larger proportions.
  These analyses and comparisons enable us clearly to un-
derstand why the culture of hemp, when judiciously managed,
especially when it is spread out and dew-rotted on the same
surface on which it was grown, is so little exhausting to the
soil, as compared with the method in which the water-rotting
process is used.
  In order to ascertain how much of the essential elements of
the soil are carried off in the merchantable product-the hemp
fibre as ordinarily sold-analyses were made of some of this,
both in the usual condition as it is to be found in our hemp
factories, and after it had been well washed with water to
remove from it as much of its adhering dirt and soluble matter
as possible.
  Two samples of the "hemp-herds," or refuse woody por-
tions of the stems, separated in the operation of braking,
were also incinerated, in the air-dried state, and the ashes
                                                              49



I5

 


16      CHEMICAL EXAMINATION OF THE ASHES OF



submitted to chemical analysis. The results are given in the
following table:
TABLE V. COMPARISON OF THE ASH INGREDIENTS OF DEW-RO1rED
    HEMP FIBRE AND HEMP HERDS, CARBONIC ACID EXCLUDED.
               HEMYP  P103, 17X-  hEm P133,  HEUP-NIIEDS, 1873.  HEN"MP-HE, 1874.
                 WASHED.    WASHED.  MOIST SEASON.XYW SEASON.
                 Inloop't. I-nop'tsIn loOp'ts I.   'to In lop'ts  n..foflt. I
               of asX  ofdied of ash.  P.  f , of ded o f dejoi
                     hemp.                   heeds.      heds.
lime .g. . .. . . . . 59.960  ok g8. 68. 694  0.7 p 1.9 98  0. 446 6a.ggo  o.676
MagVesia .       .     .141 6.      2o6   6 8.406.070 8.966  597
Potash.7.7        3.      121 3-.7 8 9. 7 4 1 9.615. t68B.670  --93
Soda....t .72 -B0 .915                          .-B   754   -8
Phosphoncracid...  85. 85.260 15.335 .161 14.401  .24 1215    .131
Solph. c-acid..... x.70   .-9   . 487 .-o5   -.6   -.017 -.038  0-3
Cloine     FooC              .o8   .0o! a tease,a teace.obe a tace.
Silica.s ,       .6.9.00     4.624 .0     .629  .    4.465  0

Per cent. of eahy phos-
phat......... 30.567  .518  09.486  .310  29.075  .251  14.807  e 67

Percent. of ash to the air.
MMte6a.1 6.....2 ... 6              1.01     , .859       _.76

  The hemp fibre, which was analyzed in the ordinary un-
washed condition, was obtained from a factory in Lexington.
It was of the crop of 1874, dark colored, and containing, per-
haps, more than the average quantity of dirt or fine soil adher-
ing to it. Washing with cold water removed some but not
all of this adhering dirt, as well as much of the soluble matters
contained in- it, reducing the per centage of the ashy residue
more than one third. Had it been thoroughly cleaned and
bleached the ash per centage would have been still more con-
siderably reduced. All the nitrogenous matters, holding phos-
phates in a comparatively soluble condition, all the alkaline
salts, would thus be dissolved out, and very little else than
silica, with a small proportion of the earthy carbonates, would
be left in the clean hemp fibre; so that exhaustion of the soil
from its production would be quite insignificant.
  Calculating on the data of the above tables, we find that
an average crop of hemp of Soo pounds to the acre removes
from the soil only a little more than thirteen pounds of ash
ingredients, or, when in the washed condition, less than eight
pounds and a half, while it is well known that a crop of wheat
of twenty bushels takes nearly twenty pounds in the grain
ISO

 


THE HEMP AND BUCKWHEAT PLANTS, &C.



alone; a crop of fifty bushels of corn removes more than thirty
pounds in the grain alone, and a crop of tobacco of one thou-
sand pounds, more than one hundred and seventy-six pounds.
  When we compare the relative proportions of the ingre-
dients of these several ashes, the result is still more to the
advantage of the hemp crop, as is to be seen in the following
tab