_Pix abietina_; _Burgundy Pitch_; F. _Poix de Bourgogne ou des Vosges_,
_Poix jaune_; G. _Fichtenharz_, _Tannenharz_.
=Botanical Origin=—_Pinus Abies_ L. (_Abies excelsa_ DC.), the Norway
Spruce Fir,[2301] a noble tree attaining an elevation of 100-160 feet,
widely distributed throughout Northern and the mountainous parts of
Central Europe, but not indigenous to Great Britain, though extensively
planted. In Russian Lapland it reaches at 68° N. lat. almost the
extreme limit of tree-vegetation, while southward it extends to the
Spanish Pyrenees. In the Alps it ascends to 6,000 feet above the level
of the sea.
=History=—In accordance with the definition of the London
Pharmacopœias and the custom of English druggists the name _Burgundy
Pitch_ is restricted to the product of the above-named species.
The pharmacologists of France use an equivalent term with the same
limitations; but in other parts of the Continent _Pix Burgundica_ has
a wider meaning, and is allowed to include the turpentines of other
_Coniferæ_. We here employ it in the English sense.
Parkinson, an apothecary of London and herbarist to King Charles I.,
speaks of “_Burgony Pitch_” as a thing well known in his time.[2302]
Dale in his _Pharmacologia_ (1693) mentions _Pix Burgundica_ as being
imported into England from Germany, and it is also noticed by Salmon
(1693), who says “it is brought to us out of Burgundy, Germany and
other places near Strasburgh.”[2303]
[2300] Wiggers and Husemann, _Jahresbericht_, 1868. 53.
[2301] _Pesse_ or _Epicéa_ of the French; _Fichte_ or _Rothtanne_ of
the Germans.
[2302] _Theater of Plants_, 1640. 1542.
[2303] _Compleat English Physician_, 1693. 1031.
Pomet, writing in Paris about the same period, discards the prefix
_Burgundy_ as a fiction, remarking that the best _Poix grasse_ comes
from Holland and Strassburg.[2304]
Whether this resin ever was collected in Burgundy we are unable to
determine. It may probably have acquired the name through having been
brought into commerce from Switzerland and Alsace by way of Franche
Comté, otherwise called Comté de Bourgogne or Haute Bourgogne.[2305]
Burgundy pitch is enumerated among the materia medica of the London
Pharmacopœia of 1677, and in every subsequent edition. In that of 1809
it was defined under the name of _Pix arida_, as the _prepared resin of
Pinus Abies_.
=Production=—Burgundy pitch is produced in Finland, in the Black Forest
in the Grand Duchy of Baden, Austria and Switzerland. On the estate
of Baron Linder at Svarta near Helsingfors, it is obtained by melting
the crude resin in contact with the vapour of water, and straining.
The quantity annually produced there was stated in 1867 to be 35,000
kilogr. (689 cwt.);[2306] that afforded by an establishment at Ilm in
the same country amounted to 80,000 kilogr. (1,575 cwt.).[2307]
In the neighbourhood of Oppenau and on the Kniebis mountain in the
Grand Duchy of Baden the stems of the firs are wounded at equal
distances by making perpendicular channels, 1½ inches wide and the
same in depth. The resin which exudes from these channels is scraped
off with an iron instrument made for the purpose, and purified by
being melted in hot water and strained. This is performed in three or
four small establishments at Oppenau and the neighbouring village of
Löcherberg. In this state the resin, which is opaque and contains much
moisture, is called _Wasserharz_. By further straining and evaporating
a portion of the water its quality is improved.
The manufacture in that part of Germany is on the decline, partly in
consequence of the timber being injured by the wounding of the trees,
so that the collecting of resin is not permitted in the large forests
belonging to the governments of Baden and Württemberg. We have had the
opportunity of observing[2308] that in the establishments in question
French turpentine or _galipot_, imported from Bordeaux, as well as
American rosin or colophony, are used in quantities certainly exceeding
that of the resin grown on the spot.
In the middle of the last century some Burgundy pitch was produced,
according to Duhamel,[2309] in the present canton of Neuchâtel, but
no such branch of industry is now pursued there, at least on a large
scale. On the other hand, in the districts of Moutier and Delémont
in the Bernese Jura this resin is still collected, though it is not
known as _Burgundy Pitch_, but is termed simply _Poix blanche_ (White
Pitch). The surveyor of the forests of this district, which is one of
the richest in _Pinus Abies_, has informed one of us that from 790 to
850 quintals are collected and exported to Basle, Zürich, Aarau and
Vaud. The pitch is worth _in loco_ (1868) 100 to 110 francs (£4 to £4
8_s._) the _bosse_ of 6 quintals. The quantities collected in other
parts of Switzerland are even less considerable.
[2304] _Hist. des Drogues_, Paris, 1694. part i. 287.
[2305] Chabræus in his _Stirpium Sciagraphia_ (1666) remarks that he
had seen the _Pesse_ (_P. Abies_ L.) in great plenty “_in Burgundicis
montibus_,” yet makes no particular allusion to its yielding resin.
[2306] _Pharm. Journ._ ix. (1876) 164; also in Hanbury’s _Science
Papers_, pp. 46 to 53.
[2307] _Oesterreichischer Ausstellungs-Bericht_, x. (Wien, 1868) 471.
[2308] I spent several days in the localities in 1873.—F. A. F.
[2309] _Traité des Arbres_, etc. i. (1775) 12.
=Description=—Pure Burgundy pitch, of which we have numerous authentic
specimens, is a rather opaque, yellowish-brown substance, hard and
brittle when cold, yet gradually taking the form of the vessel in which
it is kept. It is strongly adhesive, breaks with a clear conchoidal
fracture, and has a very agreeable, aromatic odour, especially when
heated. It does not exhibit a crystalline structure, although, as
we have frequently observed, the resin on the stem of the tree is
distinctly crystalline.
Burgundy pitch is readily soluble in glacial acetic acid, acetone,
absolute alcohol, and even in alcohol of 75 per cent. (sp. gr. 0·860),
yet its solubility in these liquids is considerably altered by the
presence of water or essential oil; and still more by the formation of
abietic acid in the resin itself. The same influences also affect the
melting point.
The crude resin of _Pinus Abies_,[2310] deprived of essential oil and
dissolved in one part of absolute alcohol, was found to deviate a ray
of polarized light 3° to the left, in a column of 50 mm.; the essential
oil deviated 8·5° to the same direction. The oil contains a small
amount of an oxygenated oil. After treatment with sodium the oil which
remains does not form a solid compound if saturated with hydrochloric
acid.
[2310] Collected by myself.—F. A. F.
=Chemical Composition=—The investigations of Maly mentioned at p. 607
afford a satisfactory elucidation of the chemical properties of the
pinic resinous exudations. They all, according to that chemist, are
mixtures of the same amorphous resin, C₄₄H₆₂O₄, with essential oils of
the composition C₁₀H₁₆. These terebinthinous juices are collected and
sold either in their natural state as _turpentine_, or deprived more
or less completely of their volatile oil, in which condition they are
represented by _Burgundy Pitch_, and finally by _rosin_ or _colophony_.
The turpentines flowing down the stems of the trees gradually lose
their transparency if allowed to dry slowly in the air, becoming at
the same time harder and somewhat granular. This alteration is due
to the incorporation of water, which at last is not only mixed with
the components of the resinous juice, but to some extent combines
chemically with the resin so as to transform it into a crystalline body
having the characters of an acid. The fact is easily observed if clear
drops of the turpentine of _Pinus silvestris_, _P. Abies_ or _P. Picea_
are collected in vials and kept perfectly dry. Thus treated these
turpentines remain transparent, but the addition of water causes after
a short time the formation of microscopic crystals of abietic acid,
rendering them more or less opaque.
If turpentines are collected before they lose their essential oil by
evaporation and oxidation, and before they have become crystalline,
they can be retained perfectly transparent by distilling off the
volatile oil without water. The distillation being most commonly
carried on _with water_, the remaining resin is opaque.
Maly is of opinion that the same amorphous resin occurs in all the
_Coniferæ_, and that it yields by hydration the same acid, namely
_Abietic_, which has been described by former chemists as _Pinic_,
_Silvic_, and _Pimaric_ acids, all of which indeed are admitted to
have the same composition. We must however remember that several sorts
of turpentine, as Canada Balsam, appear incapable, according to our
experiments, of yielding any crystalline resinoid compound whatever;
and that their amorphous resin being but partially soluble is certainly
not a homogeneous substance.
The crystals as formed naturally in the common turpentines do not
exhibit precisely the same forms as those obtained artificially
when the resins are agitated with warm diluted alcohol, as in the
preparation of abietic acid. As to _Pimaric Acid_, we have prepared it
in quantity from _galipot_, the resin of _Pinus Pinaster_, but have
always found its crystalline character entirely different from that of
abietic acid.[2311]
[2311] _Jahresbericht_ of Wiggers and Husemann for 1867. 37.
We are inclined, therefore, to think that the composition of the resins
of _Coniferæ_ is not so uniform as Maly suggests. The remarkable
variety of their essential oils is a fact which seems in favour of our
view.
=Uses=—Burgundy pitch is prescribed as an ingredient of plasters, and
thus employed is useful as a mild stimulant. In Germany it has some
economic applications, one of which is the lining of beer casks, for
which purpose a composition is used called _Brauerpech_ (brewers’
pitch), made by mixing it with colophony or _galipot_.
=Adulteration=—No drug is the subject of more adulteration than
Burgundy pitch, so much so that the very name is understood by some
pharmacologists to be that of a manufactured compound. The substance
commonly sold in England is made by melting together colophony
with palm oil or some other fat, water being stirred in to render
the mixture opaque. In appearance it is very variable, different
samples presenting different shades of bright or dull yellow or
yellowish-brown. Many when broken exhibit numerous cavities containing
air or water; all are more or less opaque, becoming in time transparent
on the surface by the loss of water. Artificial Burgundy pitch is
offered for sale in bladders; it has a weak terebinthinous odour, and
is devoid of the peculiar fragrance of the genuine. The presence of a
fatty oil is easily discovered by treatment with double its weight of
glacial acetic acid, which forms a turbid mixture, separating by repose
into two layers, the upper being oily.