SUB 
SUB 
726 SUB 
SUBERATS, salt formed with the suberic 
acid, which see. 
SUBERIC ACID maybe formed by pour- 
ing six puits of nitric acid of the specilic gra- 
vity 1.2B1 on one part of cork grated down or 
simpiy broken down into small pieces, and 
distilling the mixture with a gentle heat as 
long as red vapours continue to escape. 
As the distillation advances, a yellow matter 
like wax makes its appearance on the surface 
of the liquid. While the matter contained in 
the retort is hot, it is to be poured into a glass 
vessel, placed upon a sand-bath over a gen- 
tle fire, and constantly stirred with a glass rod. 
By this means it becomes gradually thick. 
As soon as white vapours, exciting a tickling 
in the throat, begin to disengage themselves, 
the vessel is removed from the bath, and 
the mass continually stirred till it is almost 
cold. 
By this means an orange-coloured mass is 
obtained of the consistence of honey, of a 
strong and sharp odour while hot, but hav- 
ing a peculiar aromatic smell when cold. 
On this mass twice its weight of boiling 
water is to be poured, and heat applied til! it 
becomes liquid ; and then that part of it which 
is insoluble in water is to be separated by fil- 
tration. '1 he filtred liquor becomes muddy ; 
on cooling it deposits a powdery sediment, and 
a thin pellicle forms ©n its surface. The sedi- 
ment is to be separated by filtration, and the 
liquor reduced to a dry mass by evaporating 
in a gentle heat. This mass is suberic acid. 
It is still a little coloured, owing to some 
accidental mixture, from which it may be 
purified either by saturating it with potass 
and precipitating it by means of an acid, 
or by boiling it along with charcoal-pow- 
der. 
Suberic acid thus obtained is not crystal- 
livable, but when precipitated from potass by 
an acid it assumes the form of a powder : 
when obtained by evaporation it forms thin 
irregular pellicles. 
Its taste is acid and slightly bitter; and when 
dissolved in a small quantity of boiling water 
it acts upon the throat, and excites cough- 
ing. 
It reddens vegetable blues; and when 
dropped into a solution of indigo in sulphu- 
ric acid (liquid blue, as it is called in this coun- 
try), it changes the colour of the solution, 
and renders it green. 
Water at the temperature of 60° or even 
70° dissolves only-^j. part of its weight of su- 
b'ricacid; and if the acid is very pure, only 
•j-^th part: boiling water, on the contrary, 
dissolves half its weight of it. 
When exposed to the air, it attracts mois- 
ture, especially if it is impure. 
When exposed to the light of day, it be- 
comes at last brown ; and this effect is pro- 
duced much sooner by the direct rays of the 
sun. 
When heated in a matrass, the acid sub- 
limes, and the inside of the glass is surrounded 
with zones of different colours. If the sub- 
limation is stopped at the proper time, the 
acid is obtained on the sides of the vessel in.' 
small points formed of concentric circles. 
When exposed to the heat'of the blowpipe on 
a spoon of platinum, it first melts, then be- 
comes pulverulent, and at last sublimes en- 
tirely with a smell resembling that of sebacic 
acid. 
It is not altered by oxygen gas: the othe 
acids do not dissolve it completely. Alcotio 
developes an aromatic odour, and an ether 
may be obtained by means of this acid. 
It converts the blue colour of nitrat of cop- 
per to a green ; the sulphat of copper also 
to a green ; green sulphat of iron to a deep 
yellow ; and sulphat of zinc to a golden yel- 
low'. 
It has no action either on platinum, gold, or 
nickel ; but it oxidizes silver, mercury, copper, 
lead, tin, iron, bismuth, arsenic, cobalt, zinc, 
antimony, manganese, and molybdenum. 
With alkalies, earths, and metallic oxides, 
it forms compounds known by the name of 
suberats. 
Its affinities are as follows : 
Barytes, 
Potass, 
Soda,, 
Lime, 
Ammonia, 
Magnesia, 
Alumina. 
SUBLIMATION, a process by which 
certain volatile substances are'raised by heat, 
and again condensed by cold in a solid form. 
I lowers of sulphur are made in this way'. 
Soot is also an instance of sublimation. See 
Chemistry. 
SUBNORMAL, in geometry, is a line 
which determines the point in the axis of a 
curve, where a normal, or perpendicular, 
raised from the point or contact of a tangent 
to the curve, cuts the axis. Or the subnorm- 
al is a line which determines the point where- 
in the axis is cut by a line falling perpendicu- 
larly on the tangent in the point of the con- 
tact. 
SUBPCENA, is a writ by which all persons 
under the degree of peerage are called into 
Chancery, in such case on Iv where the com- 
mon law tails, and has made no provisions? so 
as the party .who in equity has wrong, can 
have no other remedy by the rules and course 
of common law. But the peers of the realm 
in such ca-.es are called by the lord chancel- 
lor’s, or lord keeper’s letters, giving notice of 
the suit intended against them, and requiring 
them to appear. There is also a subpoena ad 
testificandum for the summoning of witnesses 
as well in chancery as other courts. 
1 here is also a subpoena in the exchequer, 
as well in the court of equity there, as in the 
office of pleas. 
SUBROGATION, or Surrogatjon, in 
the civil law, the act of substituting a person 
in the place, and entitling him to the rights, 
of another ; but, in its general sense, subroga- 
tion implies a succession of any kind, whe- 
ther of a person to a person, or of a person to 
a thing. There are two kinds of subroga- 
tion, t lie one conventional, the other legal. 
Conventional subrogation is a contract, 
whereby a creditor transfers his debt, with all 
appurtenances thereof, to the profit of a third 
person. Legal subrogation is that which the 
law makes, in favour of a person who dis- 
charges an antecedent creditor, in which case 
there is a legal translation of all rights of the 
antient creditor to the person of the new one. 
This the civilians more usually call succes- 
sion, as being wholly the work of the law ; 
and to distinguish it from the conventional 
subrogation, which they also call cession. 
SUBSIDY, in law, signifies an aid or tax 
granted to the king, bv parliament, for the 
necessary occasions of the kingdom ; and is 
to be levied on every subjec t of ability, ac- 
cording to the rate or value of his lands or 
goods : but this word, in some of our statutes, 
is confounded with that of customs. 
SUBSISTENCE, in the military art, is the 
money paid to the soldiers weekly, not 
amounting to their full pay ; because their 
clothes, accoutrements, tents, bread, &c. are 
to be paid. It is likewise the money paid to 
officers upon account, till their accounts are 
made up, which is generally once a year, and 
then they are paid their arrears. 
SUBSTtTU 1 ION, in the civil law, a dis- 
position of a testament, whereby the testator 
substitutes one heir for another, who has only 
the usutruit, and not the property of the 
thing left him. Substitution is only a kind of 
fiduciary inheritance, called also lidei com- 
missio, in regard the immediate inheritor has 
only the use or produce of the thing; the 
body thereof being substituted and appropri- 
ated to certain persons, who are likew'ise to 
have the usutruit in their turns, but are never 
to have the property. 
Substitution, in algebra, &c. is the 
putting, in the room of any quantity in an 
equation, some other quantity , w hich is equal 
to it, but expressed in another manner. 
SUB 1 ANG ENT of a curve, in the high- 
er geometry, is the line which determines the 
intersection of the tangent with the axis ; or, 
that determines the point wherein the tan- 
gent cuts the axis prolonged. 
In any equation, if the value of the sub- 
tangent comes out positive, it is a sign that 
the points of intersection ot the tangent and 
axis fall on that side ot the ordinate w here the 
vertex of the curve line lies, as in the para- 
bola and paraboloids: but it it comes out ne- 
gative, the point of intersection will fall on 
the contrary side ot the ordinate, in respect 
of the vertex, or beginning of the abscissa ; 
as in tin' hyperbola and hyperboiitorm figures. 
And universally, in all parabolifonn and hy- 
perbolitorm figures, the subtangent is equal 
to the exponent of the power of the ordinate, 
multiplied into the abscissa. 
If CB is an ordinate to AB, in anv given 
angle, terminating in any curve AC, and AB 
= x , BC zzz y, and the relation between x and 
y, that is, the nature of the curve, is expressed 
by this equation, ,v’ — 2 xxy -(- bxx — bbx -\~ hyy 
— y' = 0 ; then this will be the rule of drawing 
a tangent to it : multiply the terms of the equa- 
tion by an arithmetical progression ; suppose, 
according to the dimensions of y, 
■V s — 2.rxy -(- bxx — bbx -j- byy — 
0 1 0 0 2 3 
as also according to the dimensions of ,r, as 
x 5 L 2xxy — |— bxx — bbx — |— byy — yd: the 
3 2 2 1 6 o 
former product shall be the numerator, and 
the latter, divided by x, the denominator, of a 
fraction expressing the length of the subtangent; 
which, in this case, will be 
_ — 2 r vy 2byy — 3 y 5 
3xx — 4 xy -j- l 2bx — bb 
SUB1 ENSE, in geometry, the same with 
the chord of an arch. See Chord, 
Hence, the subtense of an angle is a right 
line supposed to be drawn between the two 
extremities of the arch that measures that 
angle. 
