50o 
RESINS. 
with a portion of that liquid*; for the) be- 
coine Opaque, and lose much ot their brittle- 
rie^. i his at least is the case with common 
losm. J hey are all, with a few exceptions, 
soluble in alcohol, especially w hen assisted by 
heat. I lie solution is usually transparent; 
and when the alcohol is evaporated, the resin 
:s obtained unaltered in its properties. When 
the solution is mixed with water, it becomes 
milky, and the resin falls in the state of a 
wnite powder. They are soluble also in sul- 
phuric ether. Many of them are soluble in 
* several ot the fixed oils, especially in the dry- 
ing oils. The greater number are soluble in 
the volatile oils; at least in oil of turpentine, 
the one commonly employed. 
Hitherto it has been affirmed by all che- 
mists, botli antient and modern, that the al- 
kalies do not exert action on the resins. 
J'ourcroy, for instance, in his last work, af- 
firms this in the most positive manner ; but 
the experiments ot Mr. Hatchett have de- 
monstrated this opinion to be completely er- 
roneous. He reduced a quantity of common 
rosin to powder, and gradually added it to a 
boiling lixivium ot carbonat of potass *'a per- 
fect solution was obtained of a clear yellow 
colour, which continued permanent after 
Jong exposure to the air. The experiment 
succeeded equally with carbonat of soda, and 
with solutions of pure potass or soda. Every 
other resin tried was dissolved as well as ro- 
sin. Mr Hatchett’s discovery must lead to 
very important consequences. The well- 
known iact, that the soap-makers in tliis coun- 
try constantly mix rosin with their soap; that 
it owes its yellow colour, its odour, audits 
easy solubility in water, to this addition ; 
ought to have led chemists to have suspected 
the solubility of resins in alkalies. No .such 
consequence, however, was drawn from this 
notorious fact. 
It has been supposed also that the acids are 
-incapable of acting upon the resins. Four- 
croy is equally positive with regard to this ; 
and Gren speaks of it in such a manner, 
that every reader must conclude that he had 
tried the effect of nitric acid upon resins. 
Net Mr. Hatchett has ascertained this opi- 
nion likewise to be erroneous, at least as far 
as nitric acid is concerned. He found that 
resins are thrown down from their solutions 
in alkalies in the state of a curdy precipitate ; 
-but when nitric acid is added in excess, the 
whole of the precipitate is redissolved in a 
boiling heat. This remarkable fact, which 
did not hold when sulphuric or muriatic acids 
were used, led him to try whether the resins 
were soluble in nitric acid. lie poured ni- 
tric acid, of the specilic gravity 1.38, on 
powdered rosin in a tubulated retort ; and by- 
repeated distillation formed a complete solu- 
tion of a brownish yellow colour. The solu- 
tion took place much sooner in an open ma- 
trass than in close vessels. The solution con- 
tinues permanent, though left exposed to the 
air. It becomes turbid when water is added ; 
but when the mixture is boiled, the whole is 
redissolved. When Mr. Hatchett collected 
the precipitate thrown down by water by fil- 
tration, he found that it still possessed" the 
properties of resin. The resin is thrown 
down from nitric acid by potass, soda, and 
ammonia ; but an excess of these alkalies re- 
dissolves the precipitate, and forms brownish 
orange coloured liquids. When Mr. Ilaich- 
«ett dissolved resin in boiling nitric acid, the 
solution was attended with a copious dis- 
charge of nitrous gas; and when the pow- 
dered resin was thrown into cold nitric acid, 
a considerable offer \ escence soon took place, 
and a porous mass was formed, commonly of 
a deep orange-colour. 
hen resins are subjected to destructive 
distillation, we obtain, according to Gien, 
carbureted hydrogen and carbonic acid gas, 
a very small portion of acidulous water, and 
much empyreumatic oil. The charcoal is 
light and brilliant, and contains no alkali. 
When volatile oils are exposed for some 
time to the action of the atmosphere, they ac- 
quire consistency, and assume the properties 
of resins. During this change they absorb a 
quantity of oxygen from the air. Westrum 
put 30 grains ot oil of turpentine into 40 cu- 
bic inches of oxymuriatic acid gas. Heat was 
evolved; the oil gradually evaporated, and 
assumed the form of vellow resin. Mr. 
Proust observed, that when volatile oil is ex- 
posed to the air, it is partly converted into a 
resin, and partly into a crystallized acid ; 
usually the benzoic or the camphoric. Hence 
we see that the oil is converted into two dis- 
tinct substances. During this change oxy- 
gen is absorbed ; and Fourcroyhas observed 
that a portion of water is also formed. It is 
probable, from these facts, that resin is vola- 
tile oil deprived of a portion of its hydrogen, 
and combined with -oxygen. 
Hermstadt affirms, that to know whether 
1 any vegetable substance contains resin, we 
have only to pour some sulphuric ether upon 
>t in powder, and expose the infusion to the 
light. If any resin is present, the ether will 
assume a brown colour. 
Having now described the general proper- 
ties of resinous bodies, it will be proper to 
take a more particular view of those of them 
which are ot the most importance, that 
we may ascertain how far each possesses the 
general characters of resins, and by what pe- 
culiarities it is distinguished from the rest. 
J he most distinguished of the resins are the 
following : 
1. Rosin. This substance is obtained 
from different species of lir ; as the pinus 
abies, sylvestris, larix, balsamea. It is well 
known that a resinous juice exudes from the 
pinus sylvestris, or common Scotch fir, which 
hardens into tears. The same exudation ap- 
pears in the pinus allies, or spruce fir. These 
tears constitute the substance called thus, or 
common frankincense. When a portion of 
hark is stripped off these trees, a liquid juice 
(lows out, which gradually hardens* This 
juice has obtained different names according 
to the plant from which it comes. The pinus 
sylvestris yields common turpentine ; the la- 
rix, V enice turpentine ; the balsamea, balsam 
of Canada, &c. All these juices, which are 
commonly distinguished by the name of tur- 
pentine, are composed of two ingredients; 
namely, oil of turpentine, and rosin. When 
the turpentine is distilled, the oil comes over, 
and the rosin remains behind. When the 
distillation is continued to dryness, the resi- 
duum is known by the name of common ro- 
sin, or colophoniuin ; but when water is mixed 
with it while yet fluid, and incorporated by 
violent agitation, the mass Is called yellow 
rosin. During winter the wounds made in 
the fir-trees become incrusted with a white 
brittle substance called barras or galipot. 
J consisting of rosin united to a small portion of 
oil. The yellow rosin made by melting and 
agitating this substance in water, is prelerred 
tor most purposes; because it is more duc- 
tile, owing probably to its still containing 
some oil. The properties of rosin are those 
which have been detailed in the former part 
ot this article. Its uses are numerous and 
well known. 
2. Mastich. This resin is obtained from 
the pistacea lentiscus ; a tree which grows in 
the Levant*, particularly in the island of 
Chios. When transverse incisions are made 
into this tree, a fluid exudes, which soon con- 
cretes into yellowish semitransparent brittle 
grains. In this state it is sold under the 
name of mastich. It softens when kept in the 
mouth, but imparts very little taste. This 
has induced surgeons to employ it to fill up 
tiie cavities of carious teeth, which it does to- 
lerably well. When heated, it melts, and ex- 
hales a fragrant, odour. It contains a little 
volatile oil. It dissolves readily in fixed oils 
and in alcohol ; but is too fusible and opaque 
to answer as a varnish. Mr. Hatchett found 
it soluble in alkalies and nitric acid with the 
phenomena described in the former part of 
this article. Its specific gravity is 1.074. 
3. Sandaraclt. T his resin is obtained from 
thejuniperus communis, or common juniper. 
It exudes spontaneously, and is usually in the 
stale of small round tears of a brown colour, 
and semitransparent, not unlike mastich, but 
rather more transparent and brittle. Besides 
the resinous part, it contains a peculiar prin- 
ciple. Mr. Hatchett found the resin of juni- 
per soluble in alkalies and nitric acid. Its 
specilic gravity is 1.092. 
4. Elemi. This resin is obtained from the 
amyris elemifera; a tree which grows in Ca- 
nada and Spanish America. Incisions are 
made in the bark during dry weather, and the 
resinous juice which exudes is left to harden 
in the sun. It comes to this country in long 
roundish cakes wrapped in flag-leaves. It is 
of a pale yellow colour, semitransparent; at 
first softish, but it hardens by keeping. Its 
smell is at first strong and fragrant, but it 
gradually diminishes. When distilled, it 
yields a portion of volatile oil. The residu- 
um is a pure resin. Its specific gravity is 
1.018. 
5. Tacamahac. This resin is obtained 
from the fagara octandra, and likewise it is 
supposed from the populus balsamifera. It 
comes from America in large oblong masses 
wrapt in flag-leaves. It is of a light-brown 
colour, very brittle, and easily melted when 
heated. Mr. Hatchett found it soluble in 
alkalies and nitric acid with the usual pheno- 
mena. Its specific gravity is 1.046. 
6. Anime . This resin is obtained from 
the hymenaca courbaril or lucust tree, which 
is a native of North America. Aniirfo re- 
sembles copal very much in its appearance ; 
but is readily soluble in alcohol, which copal 
is not: this readily distinguishes them. It is 
said to be very frequently employed in the 
making of varnishes, i ts specific gravity, ac- 
cording to Brisson, is 1.028. 
7. Ladanum, or lubdumon. This resin is 
obtained from the cystus creticus, a shrub 
which grows in Syria and the Grecian islands. 
See Labdanum. 
8. Opobalsamum, or balm of Gilead . 
r l his resin is obtained from the amyris Gi- 
