ROSIN.
717
la i , ! OI ’ F ' rttes -—Rosin is compact, solid, brittle, almost odourless andlWii S ’ w *th a smooth shining fracture, becomes electric by friction, isin * e a moderate heat, decomposable at a higher temperature, yield-ing amon S other products a volatile oil (Luscombe’s rosin oil) and an, 0 l^mablo gas (Daniell’s rosin gas), and burning in the air with anth 0VV sm °ky flame. It is insoluble in water, but soluble in alcohol,ills' 01 ’ an< ^ die volatile oils. With wax and the fixed oils it unites byn ^a,V ’ *^ ie caus tic alkalies it unites to form a resinous soap (the
Sii1 pW.
Yllo
OV
resinates, principally the pinates). Heated with concentratedvie or nitric acid mutual decomposition takes place.
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rosin is opaque and yellow, or yellowish-white. Its opacity isis to wa ter, with which it is incorporated. By continued fusion thisr i<l of, and the rosin then becomes transparent ( transparent rosin).y >n r osin or colophony is more or less brown and transparent.
Pall °. 1 iPositi on. —Rosin is a compound or mixture of pinic acid (princi-c olophonic acid (variable in quantity), sylvic acid (a small quantity),(;/■ riaces of an indifferent resin (Unverdorben, in Gmelin, Hand. d.lra • ri. 520).
Co],j acid .—May be regarded as an oxide of oil of turpentine. It is soluble in
alcohol
"Ith ( |.' ( ^ ori of an alcoholic solution of acetate of copper. Pinate of magnesia dissolves
tl | ( . . 1 ]) l _[i ,, f l °l of sp. gr. 0 883. The solution forms a precipitate (pinate of copper) on
«t Ue difficul >y in water. The ultimate composition of pinic acid (the essential con-a of rosin) is as follows (Dumas, Traite de Chim. t. v. p. 686:—
Eq.
Eq. wt.
Per cent.
Carbon . . .
. . 40 . .
. . . 240 . .
. . . 78-9
Hydrogen . .
. . 32 . .
. . . 32 . .
. . . 10-5
Oxygen . . .
. . 4
. . . 32 . .
. . . 105
Pinic acid . .
. . 1 . .
. . . 304 . .
. . . 99-9
Husnu ^Phonic acid .—Formed by the action of heat on pinic acid, and, therefore, the•Is hf ni ^ u contained in rosin varies according to the heat employed. Rosin owes^I'fial I** c< d° ur to it. It is distinguished from pinic acid by its greater affinity forl 1 . ^ases, and its slight solubility in alcohol (Berzelius , Traite de Chim. t. v.
8 "lu'hV^ric “cirf,—Is isomeric with pinic acid, from which it is distinguished by ltsm-^ 1 lt .y in cold alcohol of sp. gr. 0 883.
ti| le ^different resin .—Is soluble in cold alcohol, oil of petroleum, and oil of turpen-It forms with magnesia a compound readily soluble in water.
*Hv
'all' Sl<) .T' 0GICAL Effects. —Not being used internally, its effects when
of ^ ° w ed are scarcely known. It is probable, however, that they areriblv ^ arne kind as those of common turpentine, though very conside-Ot J lighter. In the horse it acts as a useful diuretic, in doses of five'ocal • rach ms (Youatt, The Horse, in the Libr. of Useful Knowl.) Its!l jUlr| | Iri *hier) c e is very mild. “ It may be considered,” says Dr. Maton
Hi
ei 't s Pinus), “ as possessing astringency without pungency.”
■ owdered rosin has been applied to wounds to check hemor-
^SE.
t A . # 1 L
lint tij aU( ls occasionally used for this purpose in veterinary practice.
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, Uu Wit
Principal value of rosin is in the formation of plasters and oint-