ROYAL INSTITUTION— FLOOR CLOTH MANUFACTORY. 
23 
weighing 1000 grains, was 1 yard 5§ inches, 
and its breadth 33 inches. Thus, a piece of 
cloth, amounting to 1386 square inches, or 
rather, 2772 square inches, (as both sides of 
the cloth had been equally subjected to an 
aluming process) had combined with 7'6 grains 
of alumina ; or every square inch of the cloth 
had combined with 0 0027 grains (g^o't^ ^ 
grain nearly) of alumina. 
1000 grains of the same cloth were dyed 
the palest shade of Turkey-red usually given 
to cloth. When burnt, the ashes were found 
to contain 0.8 grain of alumina. Substracting 
the 0 4 grain of alumina belonging to the cotton 
fibres, there remains 0 4 grain for the quantity 
communicated during the aluming process. 
In this case, every square inch of surface of 
the cloth had combined with 0 00012 grain of 
alumina, or less than g^^h of a grain. Yet 
this quantity of alumina small as it is, was 
essential to the permanence of the dye. For, 
when unalumed cloth was dyed with madder, 
the colour was easily washed out with water. 
When cloth to be dyed i-ed is impregnated 
with this mordant, it is not thickened, When 
applied only to particular parts of the cloth, 
by the block or cylinder, it is thickened with 
flour, or calcined starch, or gum Senegal, ac- 
cording to the nature of the style of work. 
2. OXIDE OF TIN. — Perchloride of tin 
is very much used as a mordant. The colour- 
ing matter is previously mixed with it, and 
both are applied at once. Such applications 
are usually called chemical colours.'*' The 
mixture is allowed to dry on the cloth, which 
is then merely washed with water. When 
colours are applied in this way they are easily 
altered by soap, exposure to the light, &c. 
Hence, in common language, a chemical 
colour means a fugitive colour. The colours 
produced in this way, are pink from Brazil 
wood, peach wood, and cochineal ; purple 
from logwood, and yellow from Persian 
berries. 
Perchloride of tin is much used in another 
common process of calico-printing, known 
technically, by the apellation of steam colours. 
It is decomposed and converted into stannate 
of potash. The whole piece of cloth is im- 
mersed in the liquid containing the stannate 
of potash, and dried. The peroxide cf tin is 
then deposited on the cloth, by immersing the 
piece in a solution of sal ammoniac, or sulphate 
of magnesia ; but most commonly, in a very 
weak solution of sulphuric acid. The ditfer- 
ent colouring matters, previously thickened 
wiih starch, are then printed on the cloth, 
and the whole subjected to the action of 
steam. By the joint action of moisture and 
heat, a combination takes place between the 
colouring matter and the oxide, which is thus 
rendered insoluble. And no considerable 
quantity of water is ever present to carry 
* A very general error prevails with regard 
to chemical colours, that it is the mode of ap- 
plying them which renders them fugitive. It 
is because chemical colours are made with 
changeable materials, that they are more easily 
acted on than madder colours. Brazil pink for 
instance, is equally acted upon by light and 
soap when dyed. 
olf the colouring matter, before it has com- 
bined with the mordant. 
3. PEROXIDE OF IRON— This metal- 
lic oxide is much used as a mordant. It is 
employed in the state of acetated protoxide 
of iron, formed by dissolving iron in pyrolig- 
nic acid. Within a few days after it has 
been applied to the cloth, especially if expos- 
ed to a moist atmos[)here, it loses its acid, 
and the iron becomes peroxidized. 
Acetate of iron, of the specific gravity 
1-05 gives a black, with madder. Various 
shades of purple are obtained by adding dif- 
ferent portions of the mordant and dye-stuffs. 
Different shades of red, from brown, red to 
pink, are obtained in the same way, substi- 
tuting the alum mordant of various strengths 
for the iron. Chocolates are got by mixing 
the aluminous and iron mordants, and then 
dyeing with madder. 
Indigo, oxide of manganese, catechu, &c. 
are colours per se, and therefore, require no 
mordant. 
(To he continued .) 
ROYAL INSTITUTION. 
FEBRUARY 27. 
FLOOR CLOTH MANUFACTORY .—Mr. Brande 
gave a description of this manufacture, and 
added greatly to its interest by going through 
the various steps of the process, with the as- 
sistance of some workmen employed in the 
manufactory at Knightsbridge. The main 
part of the manipulation is similar to calico- 
printing, the figures on the blocks being upon 
a much larger scale, and the cloths which are 
printed being of an infinitely greater size. 
The common dimensions of a floor cloth are 
210 or 22J square yards, and hence the im- 
mense size and often unseemly appearance of 
floor cloth works. A stout canvass is chosen 
in the first instance. This is nailed to one ex- 
tremity of a wooden frame, and stretched by 
means of hooks which are attached to the 
other sides. It is then washed with a weak 
size and rubbed over with pumice stone. No 
other substance has yet been found which an - 
swersthe purpose so well as this mineral. 
The next step is that of laying on the colour, 
which is performed by placing dabs of paint 
over the canvass with a brush, and then rub- 
bing or polishing it with a long peculiar shaped 
trowel. Four coats of paint are thus applied 
in front and three on the back of the cloth. 
To remove it from the frame w^hen these pro- 
cesses are finished, a roller on a carriage is 
employed, upon which it is rolled and convey- 
ed to the extremity of the manufactory for the 
purpose of being printed. 
It is then gradually transferred from the 
roller and passed over a table which is 30 
feet long and 4 feet wide, made of planks 
placed vertically, and as it proceeds over the 
table, the blocks, dipped in the appropriate 
colours, are applied. The colours used are 
ochre, umber, vermilion, and dilferent kinds 
of chrome, mixed up with lintseed oil and a 
little turpentine. 
The number of blocks applied to one pat- 
tern depends upon the number of colours. 
