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ashes in commerce, it is combined with
a small quantity of carbonic acid. Po-
tassa in its combined state, as has been
mentioned, page 94, consists of the high-
ly inflammable metal potassium, and oxy-
gen, one proportion of each.

Soda, or the mineral alkali, is found in
some plants that grow near the sea, and
is obtained combined with water, or car-
bonic acid, in the same manner as potas-
sa ; and, consists, as has been stated, page
94, of one portion of sodium, and two
proportions of oxygen. In its properties
it is very similar to potassa ; but may be
easily distinguished from it by this cha-
racter ; it forms a hard soap with oil ;
potassa forms a soft soap.

Pearl-ashes, and barilla, and kelp, or
the impure soda obtained from the ashes



* According to Dr. Thompson's experiments, oxalic
acid contains of 3 proportions of carbon, 4 of oxygen,
and 4 of hydrogen, a result very diflerent, indeed, from
that of the French chemists.



SIR H. DAYV S AGRICULTURAL CHEMISTRY;



151



ot marine plants, are very valuable in common in the vegetable kingdom than
commerce, principally on account of their I magnesia, and magnesia more common



uses in the manufacture of glass and
soap. Glass is made from fixed alkali,
flint, and certain metallic substances.

To know whether a vegetable yields
alkali, it should be burnt, and the ashes
washed with a small quantity of water.
If the water, after being for some time ex-
posed to the air, reddens paper, tinged
^vith turmeric, or renders vegetable blues
green, it contains alkali.

To ascertain the relative quantities of
pot-ashes afforded by different plants,
equal weights of them should be burnt ;
the ashes washed in twice their volume
of ^vater ; the washings should be ])assed
through blotting paper, and evaporated to
dryness ; the relative weights of the salt
obtained, will indicate very nearly the
relative quantities of alkali they contain.
The value of marine plants in produc-
ing soda, may be estimated in the same
manner with sufficient correctness for
commercial purposes.

Herbs, in general, furnish four or five
times, and shrubs two or three times as
much pot-ashes as trees. The leaves pro-
duce more than the branches, and the
branches more than the trunk. Vegeta-
bles burnt in a green state produce more
ashes than in a dry state. The following
table* contains a statement of the quan-
tity of pot-ashes afforded by some com-
mon trees and plants.
10,000 parts of Oak - - - 15

of Elm - - - 39

of Beach - - 12

of Vine - - - 55

of Poplar - - 7

of Thistle - - 53
of Fern - - - 62
of Cow Thistle - 196
of Worm Wood - 7.30
of Vetches - - 275
of Beans - - 200

of Fumitory - - 790
The earths found in plants are four ;
silica, or the earth of flints, alumina, or
pure clay, lime and magnesia. They are
procured by incineration. The lime is
usually combined with carbonic acid.
This substance and silica are much more



• It is founded upon the experiments of Kirwaji,
Vauqulin, and Pertuis.



than alumina. Tiie earths form a prin-
cipal part of the matter insoluble in
water, afforded by the ashes of plants.
The silica is known by not being dis-
solved by acids ; the calcareous earth,
unless the ashes have been very intensely
ignited, dissolves with effervescence in
muriatic acid. JNIagnesia forms a soluble
and crystallizable salt, and lime a diffi-
cultly soluble one with sulphuric acid.

Alumina is distinguished from the
other earths, by being acted upon very
slowly by acids; and in forming salts
very soluble in water and difficult of
crystallization with them.

The earths appear to be compounds of
peculiar metals (mentioned page 94,) and
oxygen, one proportion of each.

The earths afforded by plants are ap-
plied to no uses of common life ; and
there ai'e few cases in which the know-
ledge of their nature can be of impor-
tance, or afford interest to the farmer.

The only metalic oxides found in
plants are those of iron and manganesum:
they are detected in the ashes of plants,
but in very minute quantities only.
When the ashes of plants are reddish
brown they abound in oxides of iron.
When black or purple in oxide of man-
ganesum ; when these colors are mixed
they contain both substances.

The saline compounds contained in
plants, or afforded by their incineration,
are very various.

The sulphuric acid combined with po-
tassa, or sulphate of potassa, is one of the
most usual. Common salt is likewise
very often found in tlie ashes of plants,
likewise phosphate of lime, which is in-
soluble in water but soluble in muriatic
acid. Compounds of nitric, muriatic,
sulphuric, and phosphoric acids with al-
kalies and earths exist in the sap of many
plants or are afforded by their evapora-
tion and incineration. The salts of po-
tassa are distinguished from those of soda,
by their producing a precipitate in solu-
tions of platina ; those of lime are cha-
racterized by the cloudiness they occa-
sion in solutions containing oxalic acid ,
those of magnesia, by being rendered
cloudy by solutions of ammonia. Sul-



152



SIR H. Davy's agricultural chemistry.



phuric acid is detected in salts by the
dense white precipitate it forms in solu-
tions of baryta. Muriatic acid by the
cloudiness it communicates to solution of
nitrate of silver, and when salts contain
nitric acid, they produce scintillations by
being thrown upon burnino; coals.

As no applications have been made of
any of the neutral salts, or analogous



compounds found in plants, in a separate
state, it will be useless to describe them
individually. The following tables are
given from M. Th. de Saussure's Re-
searches on Vegetation, and contain re-
sults obtained by that philosopher. They
exhibit the quantities of soluble salts,
metalic oxides, and earths afforded by the
ashes of different plants.



NAMES OF PLANTS.


2

- So

E c


-a


a
a,

a

5 s




Constituents of 100


parts of t


It ashes. [


"a


2


1




s

'55

o






2 '^




Q


745


3
■3


a


a


en


"a


3
1-1


1. Leaves of oak, (jwercMsrofiwr,) ")
May 10. 5


13


53


47


24


0.12


3


0.64


25.24


2. Ditto, September 27,


24


55


549


17


18.25


23


14.5


1.75


25.5


3. Wood of a young oak, May 10.




5




26


28.5


12.25


0.12


1


32.58


4. Bark of ditto.




60




7


4.5


63.25


0.25


1.75


22.75


5. Entire wood of oak,




2




38.6


4.5


32


2


2.25


20.65


6. Alburnum of ditto.








32


24


11


7.5


2


23.5


7. Bark of ditto,




60




7


3


66


1.5


2


21.5


8. Cortical layers of oak,




73




7


3.75


65


0.5


1


22.75


9. Extract of wood of ditto.




61




51












10. Soil from wood of ditto.




41




24


10.5


10


32


14


8.5


11. Extract from ditto,




111




66












12. Leaves of the poplar, (pupu- ")
lus nigra,) May 26, 3


23


66


652


36


13


29


5


1.25


15.75


13. Ditto, September 12,


41


93


565


26


7


36


11.5


1.5


18


14. Wood of ditto, September 12,




8


26




16.75


27


3.3


1.5


24.5


15. Bark of ditto.




72




6


5.3


60


4


1.5


23.2


16. Leaves of hazel, {Corylusavel- ")
lana,) May 1, 3






















61




26


23.3


22


2.5


1,5


24.7


17. Ditto, washed in cold water,




57




8.2


19.5


44.1


4


2


22.9


18. Leaves of ditto, .Tune 22,


28


62


655


22.7


14


29


11.3


1.5


21,5


19. Ditto, September 20,


31


70


557


11


12


36


22


2


17


20. Wood of ditto. May 1,




5




24.5


35


8


0.25


0.12


32.2


21. Bark of ditto.




62




12.5


5.5


54


0.25


1.75


26


22. Entire wood of mulberry, (mo-")
rus nigra,) November, 3






















7




21


2.25


56


0.12


0.25


20.38


23. Alburnum of ditto.




13




26


27.25


24


1


0.25


21.5


24. Bark of ditto,




89




7


8.5


45


15.25


1.12


23.13


25. Cortical layers of ditto.




88




10


16.5


48


0.12


1


24.38


26. Entire wood of hornbeam, 7
{carpinas betulus,) Novem. 3




















4


6


346


22


23


26


0.12


2.25


26.63


27. Alburnum of ditto.


4


7


390


18


36


15


1


1


29


28. Bark of ditto,


88


134


346


4.5


4.5


59


1.5


0.12


30.38


29. Wood of horse-chesnut, (ws- ")
culushypocastanum,) May 10, 3






















35




9.5












30. Leaves of ditto. May 10,


16


72


782


50












31. Leaves of ditto, July 23,


29


84


652


24












32. Ditto, September 27,


31


86


630


13.5












33. Flowers of ditto, May 10.


9


71


873


50












34. Fruit of horse-chesnut, {xscu- 7
lushypocastanum,) Octob. 5,3




















12


34


647


82


12




0.5


0.25


5.25


35. Plants of peas, {pisum sati- )




















vum,) in flower, 3


95




49.80


17,25


6


2.3


1


24.65


36. Ditto, ripe.


81




34.25


22


14


11


2,5


17,25'


37. Plants of vetches, {viciafaba,) ")


















before flowering. May 23, 3


1 16


150


895


55.5


14.5


.3.5


1.5


0,5


24,50



Coiiiinued on ne.xt page.



PREPARATION OF INDIGtJ.



153









5


(


Jonstitufi


lis of 100


>ails lit' th


e ashrs.






s


""










o C

St




o p






2

3




-3




NAMES OF PLANTS,


sS"


v^


*^


■1




^




9








•5
o"


4i


3


P.




i


1






< "

o


(5


o


O

to


W


w


'(fi


s


S


38. Ditto in flower, June 23,


20


122


876


55.5


13.5


4.12


1.5


0.5


24.38


39. Ditto ripe, June 23,




66




50


17.75


4


1.75


0.5


26


40. Ditto, seeds separated,




115




42


5.75


36


1.75


1


12.9


41. Seeds of ditto.




33




69.28


27.92






0.5


2.3


42. Ditto, in flower, raised in dis- 7
tilled water, 5




39




60.1


30






0.5


9.4


43. (^Solydaga vulgaris,) before 7
flowering. May 1, 5




92




67.5


10.75


1.5


1.5


0.75


18.25




















44. Ditto, just in flower, July 15,




57




59


59


1.5


1.5


0.75


21


45. Ditto, seeds ripe, September20,




50




'48


11


17.25


3.5


1.5


18.75


46. Plants of turnsol, {helianihus "^




















annuus,) a month before C




147




63


67


11.56


1.5


0.12


16.67


flowering, June 23. j




















47. Ditto, in'flower, July 23,


13


137


877


61


6


12.5


1.5


0.12


18.78


48. Ditto, bearing ripe seeds, Sep- 7
tember 20. 5


23


93


753


5.15


22.5


4


3.75


0.5


17.75


49. Wheat, {trilicum sativum,) in 7
flower, 3








43.25


12.75


0.25


32


0.5


12.25








I












50. Ditto, seeds ripe,








}^


15


0.25


54


1


18.75


51. Ditto, before flowering,




79




60


11.5


0.25


12.5


0.25


15.5


52. Ditto, in flower, June 14,


16


54


699


41


10.75


0.25


26


0.5


21.5


53. Ditto, seeds ripe.




33




10


11.75


0.25


51


0.57


23


54. Straw of wheat.




43




22.5


6.2


1


61.5


1


78


55. Seeds of ditto,




13




47.16


44.5




0.5


0.25


7.6


56. Bran,




52




4.16


46.5




0.5


0.25


8.6


57. Plants of maize, (zea mays,) ~)




















a month before flowering, ^




122




69


5.75


0.25


7.5


0.25


17.25


June 23, J




















58. Ditto, in flower, July, 23,




81




69


6


0.25


7..5


0.25


17


59. Ditto, seeds ripe,




46
















60. Stalks of ditto,




84




72.45


5


1


18


0.5


3.05


61. Spikes of ditto,




16
















62. Seeds of ditto.




10




62


36




1


0.12


0.88


63. Chaff of barley, {hordeuml
vulgare,) 5




42




20


7.75


12.5


57


0.5


2.25


64. Seeds of ditto,




18




29


32.5




35.5


0.25


2.8


65. Ditto,








22


22




21


0.12


29.88


66. Oats,




31




1


24




60


0.25


14.75


67. Leaves oi rhododendron ferru- "^




















gineum, raised on Jura, a C




30




23


14


43.25


0.75


15.63


15.68


limestone mountain, June 20, j




















68. Ditto, raised on Breven, a 7
granitic mountain, June 27, j




25




21.1


16.75


16.75


2


5.77


31.52


69. Branches of ditto, June 20,




8




22.5


10


39


0.5


5.4


22.48


70. Spikes of ditto, June 27,




8




24


11.5


29


1


11


24.5



PREPARATION OF INDIGO.

By the observations of Lechenault, it
appears that in Java they make an indigo
which is superior to that formed by fer-
mentation.

The plant is washed to separate the
dirt, and then boiled in copper pots, con-
taining about seven or eight quarts of
water, until the water attains a green



color. The water is then poured into
earthen jars, holding about SO or 90
quarts, and beat up until the scum appears
bluish, the fecula is then permitted to
subside, and afterwards dried.

Indigo certainly exists in many plants.
It may be discovered by leaving the ex-
pressed juice of a plant exposed to the air
for some days, and then evaporating itj



154



WIND-MILL, (on mechanics.)



the indigo will be separated as a blue or
green powder, which will yield a ):)urple
smoke when placed on a hot iron. It
may also be dissolved in sulphuric acid,
which, with indigo, forms a permanent
blue solution.

If the indigo is mixed with green fe-
cula, as in woad, the plant must be ex-
hausted by water, and then treated with
boiling alcohol. The first solutions con-
tain much of the fecula, but the succeed-
ing ones, which are bluish, contain more
of the indigo. If these solutions are eva-
porated almost to dryness, and alcohol
again added, it will take up the fecula,
and leave the indigo.

Indigo ought to be looked for in Ga-
lega officinalis, (goal's rue,) from whence
Linnaeus says, a fine blue color is ex-
tracted; and in Scabiosasiiccisa,{



Online LibraryD. PeirceObserver and record of agriculture, Science and art (Volume v.1) → online text (page 28 of 35)