QUARTATION, is the alloying of one part of gold that is to be refined,
along with three parts of silver, so that the gold shall constitute one
_quarter_ of the whole, and thereby have its particles too far separated
to be able to protect the other metals originally associated with it,
such as silver, copper, lead, tin, palladium, &c., from the action of
the nitric or sulphuric acid employed in the subsequent parting process.
See REFINING.
QUARTZ, has been described in the article LAPIDARY.
QUASSIA, is the wood of the root of the _Quassia excelsa_, a tree which
grows in Surinam, the East Indies, &c. It affords to water an intensely
bitter decoction, which is occasionally used in medicine, and was
formerly substituted by some brewers for hops, but is now prohibited
under severe penalties. It affords a safe and efficacious fly-water, or
poison for flies.
QUEEN’s WARE. See POTTERY.
QUEEN’s YELLOW, is an antient name of Turbith Mineral, or yellow
subsulphate of mercury.
QUERCITRON, is the bark of the _Quercus nigra_, or yellow oak, a tree
which grows in North America, The colouring principle of this yellow
dye-stuff has been called _Quercitrin_, by its discoverer Chevreul. It
forms small pale yellow spangles, like those of _Aurum musivum_, has a
faint acid reaction, is pretty soluble in alcohol, hardly in ether, and
little in water. Solution of alum developes from it, by degrees, a
beautiful yellow dye. See CALICO-PRINTING and YELLOW DYE.
QUICKLIME; see LIME.
QUICKSILVER; see MERCURY.
QUILL; see FEATHERS.
QUININA. This medicine is now prepared in such quantities as to
constitute a chemical manufacture. Quinina and cinchonina are two
vegetable alkalis, which exist in Peruvian bark or cinchona; the pale or
gray bark contains most cinchonina, and the yellow bark most quinina.
The methods of extracting these bases are very various. In general,
water does not take them out completely, because it transforms the
neutral salts in the barks into more soluble acidulous salts, and into
less soluble sub-salts. To exhaust the bark completely, one or other of
the following solvents is employed:
1. _Alcohol._--An extract by this menstruum, is to be treated with very
dilute warm muriatic acid, in order to dissolve every thing thus
soluble; the acid liquor is to be saturated with magnesia, by boiling it
with an excess of this earth; the precipitate is to be dried, filtered,
and then exhausted by boiling-hot alcohol.
2. _Dilute acids._--Boil the bark, coarsely pounded, with eight times
its weight of water, containing 5 per cent. of the weight of the bark of
sulphuric acid. This treatment is to be repeated with a fresh quantity
of dilute acid. The whole liquors must be filtered, the residuum
strained, and the solution mixed with quicklime, equal to one fourth of
the bark employed. This mixture, after having been well stirred, is to
be strained, whenever it acquires an alkaline reaction, that is, tinges
reddened litmus paper blue, or turmeric brown. The calcareous mass is to
be now washed with a little water, and dried, and then boiled thrice
with spirit of wine of sp. grav. 0·836. This solution being filtered, is
to be mixed with a little water, and distilled. The bases, cinchonina
and quinina, remain under the form of a brown viscid mass, and must be
purified by subsequent crystallization, after being converted into
sulphates.
3. _An alkali, and then an acid._--The object of this process is, to
retain the vegetable alkalis in the bark, while with the alkaline water
we dissolve out the acids, the colouring matters, the extractive, the
gum, &c. Boil for an hour one pound of the bark with six pounds of
water, adding by degrees a little solution of potash, so that the liquor
may have still an alkaline taste when the boiling is over. Allow it to
cool, filter, wash the residuum with a little water, and squeeze it.
Diffuse it next in tepid water, to which add by degrees a little
muriatic acid, till after a prolonged digestion the mixture shall
perceptibly redden litmus paper. Filter the liquor, and boil it with
magnesia. The precipitate being washed and dried, is to be treated with
hot alcohol, which dissolves the quinina and cinchonina.
Obtained by any of the above methods, the quinina and cinchonina are
more or less coloured, and may be blanched by dissolving them in dilute
muriatic acid, and treating the solution with animal charcoal.
There are several methods of separating these two vegetable alkalis.
1. When their solution in spirit of wine is evaporated by heat to a
certain point, the greater part of the cinchonina crystallizes on
cooling, while the quinina remains dissolved.