Lee ener 2 a SS SSS 
538 BRICK-MAKING. 
last are used for inside partitions, backing walls 
that are to be plastered upon, and other work 
that is neither exposed to the eye nor the weather. 
These several varieties of brick have each a se- 
parate price, the best being worth almost twice 
as much as the worst. If the fire has not been 
carefully attended to, and has been permitted to 
get too violent, a few of the lower bricks will be- 
come distorted by partial fusion, and may fuse 
and adhere together, when they are called clink- 
ers, and are useless for building purposes, but 
form an excellent road material. In the United 
States the names of bricks are different, but 
derived from the same source, being called hard 
burnt or arch bricks, body bricks, and soft or 
salmon bricks; though this last name is gener- 
ally altered by workmen intosammy. ‘The good- 
ness of a brick is derived from its regular shape 
and appearance, its tenacity and hardness, its 
sound, and by its not absorbing water, or being 
affected by frost. The tenacity and hardness are 
judged of by striking one brick against another, 
or letting them fall upon stone pavement. Good 
bricks should have a sound approaching to that 
of a metal when so treated, and they ought to 
ring, and bear a very hard blow with the edge 
of the trowel, before they divide. If they readily 
break with a blow, or crumble to dust by a fall, 
such bricks are of the soft or sammy kind, and 
are unfit for introduction into a heavy wall, par- 
ticularly on the outside of it, as they will be sure 
to be attacked by frost, and crumble to pieces. 
The absorbency of bricks is judged of by weigh- 
ing them in the dry state, and then soaking 
them in water for an hour, and weighing them 
again. Those bricks that take up the greatest 
quantity of water, are the least fit for use, when 
they are to be exposed to its action. The aver- 
age weight of a sound and dry London stock brick 
is 4 pounds 15 ounces avoirdupois. 
Independent of the above, two other kinds of 
brick are made, called cutters or rubbers, and fire- 
bricks. Cutters or rubbers are very common in 
London. Theyare made of the best and most select 
materials, passed through a much finer sieve or 
strainer than the other bricks, and the whole 
manufacture is conducted with peculiar care, on 
which account they are expensive. They derive 
their name from their being so perfectly homo- 
geneous, and free from stones or hard parts, that 
they may be cut with a saw, or chopped to any 
form, and then rubbed on a rubbing-stone until 
they obtain a perfectly flat surface. They are 
only used for ornamental purposes, such as con- 
structing gauged or rubbed arches over doors or 
windows, niche heads, and the like. Fire-bricks 
are used for lining the insides of furnaces of all 
kinds, in which the heat may be so great as to | 
fuse and vitrify bricks of ordinary materials. 
They are also used for that part of the setting of 
steam-engine boilers that is most exposed to the 
fire, and for lining the insides of fire-places in- 
tended for burning anthracite coal. ‘'wo varie- | 
BRICK-WORK. 
ties of them are made, called Stourbridge and 
Windsor fire-bricks, both excellent, but of very 
different qualities, and they both derive their 
value from the peculiar local earth of which they 
are formed. The Stourbridge brick is always 
larger than other bricks, of a pale yellow or red 
colour, and when well burnt so hard that it will 
give fire with steel, and has no absorbent power. 
When broken, it may be seen that this brick 
consists chiefly of the same brick previously 
burnt, and reduced to coarse powder, and then 
made over again with an additional quantity of 
the same fire-clay. The Windsor brick, on the 
contrary, is made below the usual size, and is so 
soft and tender, that it can scarcely be handled 
without breaking, and when broken-its whole 
substance is discovered to be nothing but sand, 
cemented and held together by a very minute 
quantity of argillaceous earth. This brick is of 
a deep, but bright red colour throughout, and is 
so soft that it may be cut to any required form 
by a common saw or knife, notwithstanding 
which, it withstands a higher heat than the for- 
mer kind, and becomes very hard and durable 
after it has been exposed to such heat. On this 
account it is constantly used for forming the 
arch over wind or reverberating furnaces for 
melting iron. A similar brick is made at Cheam 
in Surrey, and as they are all stamped with PP. 
they are known under the name of PP. or Non- 
such bricks. The hard brick should be used in 
all furnaces subject to blows or concussions, as 
when large logs of wood are thrown in, or the 
fire has to be raked with large iron pokers; but 
for domes, or places not likely to be disturbed, 
and where the heat is very great, the soft bricks 
will be found preferable. Large blocks, called 
lumps, are made of the Stourbridge material, and 
are very useful in the construction of many fur- 
naces. Fire-bricks are often made wedge-formed 
for building arches, and in segments of circles, 
for building round furnaces or flues. 
Common brick earth is frequently formed into 
what are called drain bricks; they are made 
large enough to admit of having a semicircular 
cavity of about three inches diameter sunk into 
one of their sides, so that two of them inverted, 
one over the other, form a three inch tube, with 
a square outside.—Millington. 
BRICK-WORK. In using bricks for building 
purposes, an even surface or foundation is first 
prepared, and should be truly level in each direc- 
tion. This may be covered with mortar, and the 
bricks are then placed upon it flatwise, or with 
their broadest surfaces upwards and downwards, 
with mortar filled in between their vertical joints; 
but the general practice in beginning a wall is to 
lay the first or foundation course dry, or without 
mortar ; that done, another layer of bricks is 
placed above the first, each layer being called a 
course of brick-work. Any course being finished, 
mortar is laid over a part of its upper surface to 
bed the bricks of the next course, and in this 
le 
