382 SULPHURIC ACID. 
skin. In veterinary medicine, it is the grand 
remedy for mange; and, when combined with 
nitre and antimony, is an excellent alterative 
in grease, hidebound, surfeit, and other similar 
diseases of the horse; and serves also as an efli- 
cient ingredient in balls for cough and fever. 
SULPHURIC ACID. A compound of one equi- 
valent of sulphur and three equivalents of oxy- 
gen. It was discovered by Basil Valentine to- 
ward the close of the 15th century; and is often 
though very improperly called, in popular phra- 
seology, oil of vitriol. It naturally occurs in 
small quantities, concretely in the cavities of 
some volcanic mountains, and fluidly in some 
mineral waters; and it is manufactured on a 
large scale, for the purposes of medicine and the 
arts, either by subjecting protosulphate of iron 
to destructive distillation in close vessels, or by 
burning a mixture of eight parts by weight of 
sulphur and one of nitrate of potash in a pecu- 
liarly constructed furnace, connected with a 
large, leaden-walled, water-supplied, condensing 
chamber. The former method is the oldest, and 
continues to be practised in several places on the 
Continent, and yields a dense, oily - looking, 
brownish liquid, which emits copious white va- 
pours when exposed to the air, and is commonly 
called fuming sulphuric acid, and has a specific 
gravity of from 1896 to 1:9, and consists of two 
equivalents of anhydrous acid and one equivalent 
of water; and the latter method is practised in 
Britain and in most parts of the Continent, and 
yields a liquid which generally contains about 
three or four per cent. of sulphate of potash and 
sulphate of lead, and requires to be freed from 
these impurities by a process of precipitation and 
distillation, and is then a dense, oily - looking, 
colourless fluid, having a specific gravity of from 
1°847 to 1°85, and consisting of about 81°54 parts 
of anhydrous acid and 18-46 of water. Sulphu- 
ric acid as it occurs in commerce, therefore, is 
always more or less hydrous; and, as it hasa 
very powerful affinity for water, and unites with 
it in all proportions, it suffers the utmost pos- 
sible facility of adulterating dilution; so that 
persons purchasing it, in any considerable quan- 
tity or for any nice purpose, require to look well 
to its strength; and this may, in every case, be 
readily ascertained by saturating a specimen 
with subcarbonate of soda,—every 100 grains of 
that salt having the power to neutralize 92 
grains of the concentrated acid of specific gra- 
vity 1:848. 
Sulphuric acid is one of the strongest acids 
known; and is terribly corrosive. It has a fu- 
riously sour taste, and exhibits in an energetic 
manner all the reactions characteristic of power- 
ful acids. It combines with all alkaline sub- 
stances, abstracts alkaline bases from their com- 
bination with all other acids, and carbonizes 
all animal and vegetable substances, with for- 
mation of water. It acquires a brown colour 
from the mixture of any vegetable matter,—a 
—— 
W 
SULPHURWORT. 
brown, green, or blue tint from the addition to 
it of a small quantity of sulphur,—a green colour 
from selenium,—a crimson one from tellurium,— 
and successively a pink and a dark reddish brown 
one from a minute quantity of charcoal. It 
freezes at 15° into six-sided prismatic crystals, 
bevelled at both extremities; but when diluted 
with water down to the specific gravity of 1°78, 
it freezes at 45°, or 18 degrees above the freez- 
ing-point of water,—so that at all seasons, ex- 
cept summer and the warmer parts of spring 
and autumn, it is liable, in this diluted state, 
to burst the bottles in which it is kept. The 
combination of sulphuric acid and water always 
evolves sudden and intense heat, and requires to 
be conducted with caution; for when four parts 
by weight of the cold acid are instantly mixed 
with one part of cold water, the mixture sud- 
denly attains a temperature of 300° Fahrenheit. 
Sulphuric acid absorbs water so greedily and 
rapidly from the atmosphere as to increase its 
weight one-third in 24 hours, and to double its 
weight in a month; so that it needs to be kept 
in vessels with air-tight stoppers. In conse- 
quence of its powerful affinity for water, it causes 
the sudden liquefaction of snow, and is employed 
in the process of freezing water by its own eva- 
poration, and, when mixed in due _ proportion 
with snow, generates intense cold; and probably 
it is the action of the same fearfully fierce affinity 
which constitutes its power of destroying the 
skin, forming ethers, and decomposing animal 
and vegetable substances. 
Sulphuric acid has many uses in the arts,— 
chiefly, however, in connexion with the sul- 
phates; and it has of late years come into ex- 
tensive and important use upon the farm, in 
connexion with the economical preparation of 
bone-manure. See the article Bonr- Manure. 
Diluted sulphuric acid may also be employed as 
a means of increasing the fertility of all calcare- 
ous soils in the growth of whatever crops are 
benefited by the action of gypsum; for an appli- 
cation to such soils of a mixture of 100 parts of 
concentrated sulphuric acid and from 800 to 
1,000 parts of water is equivalent to the applica- 
tion of 176 parts of gypsum. See the article 
GyPsuM. 
SULPHURWORT,—botanically Peucedanum. 
A genus of herbaceous plants, of the umbellifer- 
ous order. The medicinal species, or hog’s fen- 
nel, Peucedanum officinale, is a perennial-rooted 
indigen of the salt marshes of some parts of Hng- 
land. Its root comprises many strong fibres, 
which run deep into the ground; its stem is 
cylindrical, solid, striated, branching, leafy, and 
about 6 feet high; its leaves are repeatedly com- 
pound, and have very narrow, entire, acute leaf- 
lets; its umbels are large, and comprise numerous 
smooth rays; its flowers are yellow, and bloom 
from May till July ; and its fruit is at first reddish, 
and afterwards assumes a tawny brown colour, 
This plant takes its names of sulphurwort and 
