_Lignum Campechianum v. Campescanum_; _Logwood_, _Peachwood_; F. _Bois
de Campèche_, _Bois d’Inde_; G. _Campecheholz_, _Blauholz_.
=Botanical Origin=—_Hæmatoxylon campechianum_ L., a spreading tree[821]
of moderate size, seldom exceeding 40 feet in height, native of the
bay of Campeachy, Honduras and other parts of Central America. It
was introduced into Jamaica by Dr. Barham[822] in 1715, and is now
completely naturalized in that and other of the West Indian Islands.
=History=—Hernan Cortes in his letter to the Emperor Charles V., giving
an account of his expedition to Honduras in 1525,[823] refers to the
Indian towns of Xiculango and Tabasco as carrying on a trade in cacao,
cotton cloth, and _colours for dyeing_,—in which last phrase there may
be an allusion to logwood. We have sought for some more definite notice
of the wood in the _Historia de las Indias_ of Oviedo,[824] the first
chronicler of America, but without much success.
Yet the wood must have been introduced into England in the latter
half of the 16th century, for, in 1581, an Act of Parliament[825]
was passed, abolishing its use and ordering that any found should be
forfeited and burned. In this Act the obnoxious dye is described as “a
certain kind of ware or stuff called _Logwood_ alias _Blockwood_ ... of
late years ... brought into this realm of England.” The object of this
measure was to protect the public against the bad work of the dyers,
who, it seems, were unable at that period to obtain durable colours by
the use of logwood. Eighty years later the art of dyeing had so far
improved that logwood was again permitted,[826] the colours produced by
it being declared as lasting and serviceable as those made by any other
sort of dyewood whatsoever.
The wood is mentioned by De Laet (1633) as deriving its name from the
town of Campeachy, whence, says he, it is brought in great plenty to
Europe.[827]
[821] Fig. in Bentley and Trimen, _Med. Plants_, part 5 (1876).
[822] _Hortus Americanus_, Kingston, Jamaica, 1794. 91.
[823] _Fifth Letter of Hernan Cortes to the Emperor Charles V._, Lond.
(Hakluyt Society) 1868. 43.
[824] The first edition bears date 1535. We have used the modern one of
Madrid, 1851-55, 4to., and may refer in particular to tom. i. lib. ix.
c. 15, iii. lib. xxxi. c. 8 and c. 11.—See Appendix: Fernandez.
[825] 23 Eliz. c. 9.
[826] 13-14 Car. ii. c. 11. sect. 26 (A.D. 1662), by which the Act of
Elizabeth was repealed.
[827] _Novus Orbis_, 1633. 274 and 265.
As a medicine, logwood was not employed until shortly before the year
1746, when it was introduced into the London Pharmacopœia under the
name of _Lignum tinctile Campechense_.
=Description=—The tree is fit to be felled when about ten years old;
the dark bark and the yellowish sapwood are chipped off, the stems
cut into logs about three feet long, and the red heartwood alone
exported. By exposure to air and moisture, the wood acquires externally
a blackish-red colour; internally it remains brownish red. It splits
well, although of a rather dense and tough texture.
The transverse section of a piece of logwood exhibits to the naked eye
a series of very narrow concentric zones, formed by comparatively large
pores, and of small parenchymatous circles separated by the larger and
darker rings of the proper woody tissue. The numerous medullary rays
are visible only by means of a lens. The wood has a pleasant odour.
For use in pharmacy, logwood is always purchased in the form of chips,
which are produced by the aid of powerful machinery. The chips have a
feeble, seaweed-like odour, and a slightly sweet, astringent taste,
better perceived in a watery decoction than by chewing the dry wood,
which however quickly imparts to the saliva its brilliant colour.
=Microscopic Structure=—Under a high magnifying power, the concentric
zones are seen to run not quite regularly round the centre, but in a
somewhat undulating manner, because they do not correspond, as in our
indigenous woods, to regular periods of annual growth. The vascular
bundles contain only a few vessels, and are transversely united by
small lighter parenchymatous bands. The latter are made up of large,
cubic, elongated or polygonal cells, each loaded with a crystal of
oxalate of calcium. The large punctuated vessels having frequently
150 mkm. diameter, are surrounded by this woody parenchyme, while
the prevailing tissue of the wood is composed of densely packed
prosenchyme, consisting of long cylindrical cells (_libriform_) with
thick, dark red-brown walls having small pores.
The medullary rays are of the usual structural character, running
transversely in one to three straight rows; in a longitudinal
section, the single rays show from 4 to 40 rows succeeding each other
perpendicularly. No regular arrangement of the rays is obvious in a
longitudinal section made in a tangential direction. The colouring
matter is chiefly contained in the walls of the ligneous tissue and the
vessels, and sometimes occurs in crystals of a greenish hue within the
latter, or in clefts of the wood.
=Chemical Composition=—Logwood was submitted to analysis by Chevreul as
early as the year 1810,[828] since which period all contributions to
a knowledge of the drug refer exclusively to its colouring principle
_Hæmatoxylin_, which Chevreul obtained in a crystallized state and
called _Hématine_. The very interesting properties of this substance
have been chiefly examined by Erdmann (1842) and by O. Hesse (1858-59).
[828] _Annals de Chimie_, lxxxi. (1812) 128.
Erdmann obtained from logwood 9 to 12 per cent. of crystallized
hæmatoxylin, which he showed to have the formula C₁₆H₁₄O₆. In a pure
state it is colourless, crystallizing with 1 or with 3 equivalents
of water, and is readily soluble in hot water or in alcohol, but
sparingly in cold water or in ether. It has a persistent sweet taste
like liquorice. The crystals of hæmatoxylin acquire a red colour by
the action of sunlight, as likewise their aqueous solution. They are
decomposed by ozone but not by pure and dry oxygen. In presence of
alkalis, hæmatoxylin exposed to the air quickly yields dark purplish
violet solutions, which soon acquire a yellowish or dingy brownish
colour; hence in analytical chemistry hæmatoxylin is used as a test for
alkalis.
By the combined action of ammonia and oxygen, dark violet crystalline
scales of _Hæmateïn_, C₁₆H₁₄O₆ + 3 OH₂, are produced.[829] They show a
fine green hue, which is also very commonly observable on the surface
of the logwood chips of commerce. Hæmateïn may again be transformed
into hæmatoxylin by means of hydrogen or of sulphurous acid.
Hæmatoxylin separates protoxide of copper from an alkaline solution
of the tartrate, and deviates the ray of polarized light to the right
hand. It is not decomposed by concentrated hydrochloric acid; by
melting hæmatoxylin with potash, pyrogallol (pyrogallic acid, C₆H₆O₃)
is obtained. Alum and the salts of lead throw down precipitates from
solutions of hæmatoxylin, the latter being of a bluish-black colour.
Logwood affords upon incineration 3·3 per cent. of ash.
The colouring matter being abundantly soluble in boiling water, an
_Extract of Logwood_ is also prepared on a large scale. It occurs in
commerce in the form of a blackish brittle mass, taking the form of
the wooden chest into which it is put while soft. The extract shares
the chemical properties of hæmatoxylin and hæmateïn: whether it also
contains gum requires investigation.
=Production and Commerce=—The felling and shipping of logwood in
Central America have been described by Morelet,[830] who states that in
the woods of Tabasco and Yucatan the trade is carried on in the most
irrational and reckless manner. By advancing money to the natives, or
by furnishing them with spirits, arms, or tools, the proprietors of
the woods engage them to fell a number of trees in proportion to their
debts. This is done in the dry season, the rainy period being taken
for the shipment of the logs, which are conveyed chiefly to the island
of Carmen in the Laguna de Terminos in South-western Yucatan, and to
Frontera on the mouths of the Tabasco river, at which places European
ships receive cargoes of the wood.
In 1877 the export of Laguna de Terminos amounted to 528,605 quintals
(one quintal = 46 kilogrammes), that from Port-au-Prince, Hayti, in
1872, nearly to 90,000 tons.
Four sorts of logwood are found in the London market, namely
_Campeachy_, quoted[831] at £8 10_s._ to £9 10_s._ per ton; _Honduras_,
£6 10_s._ to £6 15_s._; _St. Domingo_, £5 15_s._ to £6; _Jamaica_,
£5 2_s._ 6_d._ to £5 10_s._ The imports into the United Kingdom were
valued in 1872 at £233,035. The quantities imported during that and the
previous three years were as follows:—
1869 1870 1871 1872
50,458 tons. 62,187 tons. 39,346 tons. 46,039 tons.
[829] Benedikt, in 1875, assigned them the formula C₄₈H₃₉O₁₈N + 9 OH₂.
[830] _Voyage dans l’Amérique centrale, l’île de Cuba et le Yucatan_,
Paris, 1857.
[831] _Public Ledger_, 28 Feb. 1874.
In 1876 the import was 64,215 tons, valued at £415,857. The largest
quantity is supplied by the British West India Islands. Hamburg also
imports annually about 20,000 tons of logwood.
=Uses=—Logwood in the form of decoction is occasionally administered
in chronic diarrhœa, and especially in the diarrhœa of children. Cases
have occurred in which its use has been followed by phlebitis. Its
employment in the art of dyeing is far more important.
=Adulteration=—The woods of several species of _Cæsalpinia_ imported
under the name of _Brazil Wood_ and used for dyeing red, bear an
external resemblance to logwood, with which it is said they are
sometimes mixed in the form of chips. They contain a crystallizable
colouring principle called _Brasilin_, C₂₂H₂₀O₇, or, according to
Liebermann and Burg (1876), C₁₆H₁₄O₅, which affords with alkalis _red_
and not bluish or purplish solutions, and yields trinitrophenol,
C₆H₂(NO₂) 3OH (picric acid), when boiled with nitric acid, while
hæmatoxylin yields oxalic acid only. The best source for brasilin is
the wood of _Cæsalpinia Sappan_ L., a tree of the East Indies, well
known as _Bakam_, _Brazil Wood_, _Lignum Brasile_, _Verzino_ of the
Italians, an important object of commerce during the middle ages.[832]