SUL 
compound of sulphuric acid and lime, sulphat 
of lime, &c. 
It absorbs a very considerable quantity of 
nitrous gas, and acquires by that means a 
purplish colour. 
Its affinities are as follows: 
Barytes, Ammonia, 
Strontian, Glucina, 
Potass, Yttria, 
Soda, Alumina, 
Lime, Zirconia, 
Magnesia, Metallic oxides. 
This is one of the most important of all 
the acids, not only to the chemist but to the 
i manufacturer also ; being employed to a 
very great extent in a variety of manufac- 
ture', especially in dyeing. 
Sulphurous acid. Though some of the 
properties of this acid must have been known 
in the remotest ages, as it is always formed 
during the slow combustion of sulphur, 
| Stahl was the tirst chemist who examined it, 
| and pointed out its peculiar nature. His 
' method of procuring it was to burn sulphur 
at a low temperature, and expose to its flames 
j cloth dipped in a solution of potass. By this 
method he obtained a combination of potass 
I and sulphurous acid ; for at a low tempera- 
ture sulphur forms by combustion only sul- 
phurous acid. Scheele pointed out, iji 1771, 
a method of procuring sulphurous acid in 
quantities. Dr. Priestley, in 1 774, obtained 
it in the gaseous form, and examined its pro- 
perties while in a state of purity. 
1. Sulphurous acid may be procured by 
the following process : Put into a glass retort 
two parts of sulphuric acid and one part of 
.mercury, and apply the heat of a lamp ; 
the mixture effervesces, and a gas issues 
from the beak of the retort, and may be re- 
ceived in glass jars filled with mercury, and 
standing in a mercurial trough. This gas is 
sulphurous acid. 
2. Sulphurous acid, in the state of gas, is 
colourless and invisible like common air. It 
jis incapable of maintaining combustion ; nor 
[can animals breathe it without death. It has 
a strong and suffocating odour, precisely the 
same with that exhaled by r sulphur burning 
with a blue flame : sulphur, by such a com- 
bustion, being totally converted into a sul- 
phurous acid. Its specific .gravity, accord- 
ing to Bergman, is 0.00240 ; according to 
Lavoisier, 0.00251. It is therefore some- 
what more than twice as heavy as air. One 
hundred cubic inches of it weigh nearly 63 
{grains. 
| 3. This acid reddens vegetable blues, and 
gradually destroys the greater number of 
them. It exercises this power on a great 
variety of vegetable ana animal colours. 
Hence the use of the fumes of sulphur in 
bleaching wool and in whitening linen stained 
by means of fruits. 
4. Dr. Priestley discovered, that when 
a strong heat is applied to this acid in close 
vessels, a quantity of sulphur is precipitated, 
and the acid is converted into sulphuric. Ber- 
thollet obtained the same result ; but Four- 
jcroy and Vauquelin could not succeed. 
5. Water absorbs this acid with avidity. 
According to Dr. Priestley, 1000 grains of 
wafer, at the temperature 54.5°, absorb 39.6 
grains of this acid. Fourcroy, on the other 
hand, affirms that water at 40° absorbs the 
third of its weight of sulphurous acid gas. 
SUL 
Ice absorbs this gas very rapidly, and is in- 
stantly melted. Water saturated with this 
gas, in which state it is known by the name 
of liquid sulphurous acid, or sulphurous acid, 
is of the specific gravity 1.040. It may be 
frozen without parting with any of the acid 
gas. When water, which has been saturated 
with this acid at the freezing temperature, 
is exposed to the heat of 65.25°, it is filled 
with a vast number of bubbles, which con- 
tinually increase and rise to the surface. 
These bubbles are apart of the acid sepa- 
rating from it. It freezes a few degrees be- 
low 32°. 
6. When liquid sulphurous acid is exposed 
to atmospheric air or to oxygen gas, it gradu- 
ally combines with oxygen, and is converted 
into sulphuric acid. This change takes place 
more completely if the acid is combined with 
an aikali or earth. When a mixture of sul- 
phurous acid gas and oxygen gas is made to 
pass through a red-hot porcelain tube, the 
two bodies combine, and sulphuric acid is 
formed. 
7. Of the simple combustibles, sulphur and 
phosphorus have no action on it whatever; 
hydrogen gas and charcoal do not alter it 
while cold, but at a red-heat they decom- 
pose it completely; water or carbonic acid 
is formed, and sulphur deposited. 
8. Neither azote nor muriatic acid produces 
any change on it. 
9. Sulphurous acid does not seem capable 
of oxidizing or dissolving any of the metals 
except iron, zinc, and manganese. 
10. It combines with alkalies, earths, and 
metallic oxides, and forms salts known by T the 
name of sulphites. 
11. Sulphuric acid absorbs this gas in con- 
siderable 'quantity. It acquires a yellowish- 
brown colour, a penetrating odour, and the 
property of smoking when exposed to the 
air. When this mixture is distilled, the first 
vapour which comes over, and which is a 
compound of the two acids, crystallizes in 
long white prisms. This singular compound, 
formerly known by the name of glacial sul- 
phuric acid, smokes in the air ; and when the 
atmosphere is moist, melts with effervescence. 
When thrown into water, it hisses like a red 
iron. It lias the odour of sulphurous acid. 
Fourcroy has lately demonstrated, that this 
is a compound of sulphuric and sulphurous 
acids. 
12. The affinities of sulphurous acid, as 
far as they have been investigated, are as 
follow: 
Barytes, Magnesia, ) 
Lime, Ammonia, y 
Potass, Glucina, 
Soda, Alumina, 
Strontian, Zirconia. 
13. As this acid is formed by the combus- 
tion of sulphur, it cannot be doubted that it 
is composed of the same ingredients with sul- 
phuric acid ; and as it is evolved from sul- 
phuric acid by the action of sulphur, and like- 
wise by some of the metals, it cannot be doubted 
that it contains a smaller proportion of oxy- 
gen. But no precise set of experiments has 
yet been made to determine the proportion of 
its component parts. Fourcroy affirms that 
it contains 
85 sulphur 
15 oxygen 
1 0 £>. 
4 Z 2 
SUP 731 
But he does not inform us upon what evi 
deuce lie assigns these proportions. 
SUM, m mathematics, signifies the quan- 
tity that arises from the addition of two or 
more magnitudes, numbers, or quantities 
together. 
The sum of an equation is, when the ab- 
solute number being brought over to the 
other side of the equation, with a contrary 
sign, the whole becomes equal to 0 ; thus, 
the sum of the equation x 3 — 12 x 2 -j- 41 x 
— 42, is x s — ■ 12 x 2 -j- 41 x — 42 = 0. See 
Algebra, and Arithmetic. 
SUMACH. See Rhus. 
SUN. See .Astronomy. 
SUNDAY. See Lord’s Day. 
SUPERCARGO, a person employed by 
merchants to go a voyage, and oversee their 
cargo, or lading, and dispose of it to the best 
advantage. 
SUPERFICIES, or Surface. See Ge- 
ometry. 
SU PERSEDEAS, a writ that lies in a great 
many cases, and signifies in general, a com- 
mand to stay proceedings, on good cause 
shewn, which ought otherwise to proceed. 
By a supersedeas, the doing of a thing, which 
might otherwise have been lawfully done, 
is prevented; or a thing that has been done, 
is (notwithstanding it was done in a due course 
of law) thereby made void. 4 Bac. Abr. 
667. 
A supersedeas is either expressed or im- 
plied ; an express supersedeas is sometimes 
by writ, sometimes without a writ ; where it 
is by writ, some person to whom the writ is 
directed, is thereby commanded to forbear 
the doing something therein mentioned; or 
if the thing has been already done, to revoke', 
as that can be done, the act. 4 Bac. Abr. 667. 
SUPER STATUTO de articulis 
cleri, in law, a writ that lies against the 
sheriff, or other officer that distrains in the 
king’s highway, or in the lands antiently 
given to the church. 
Super statuto facto pour sene- 
schal et marshal de roy, &c. a writ 
which lies against the steward or marshal, 
for holding plea of freehold in his court, or 
for trespass, or contracts not made within the 
king’s household. 
SUPPLIES, the sums granted by parlia- 
ment for defraying the public expenditure 
for the current year. The known or pro- 
liable amount of the different branches of 
the year’s expences, is stated to the house 
of commons in a committee of supply, by the 
chancellor of the exchequer; and after "they 
have been voted by the committee, are for- 
mally granted by an act of parliament. The 
granting of the annual supplies as well as per- 
manent taxes, is a peculiar privilege of the 
house of commons, who never permit any 
alteration or amendment to be made by the 
lords, in the bills passed for this purpose. 
The grants of parliament were original'v 
considered, merely as temporary aids, to 
assist the sovereign in defraying such extra- 
ordinary expences as he was subject to for 
the benefit of the public ; and unless the 
commons happened to entertain at the time, 
any particular jealousy of the crown and its 
ministers, the sum granted was commonly 
left entirely to their disposal. But after the 
restoration of Charles 11., not only more 
frequent grants were demanded, but, in con- 
sequence of the property to which the crown 
