AN IMPROVED MODE OF PREPARING OR TREATING SILK
Year: 1874

page_text: PROVISIONAL SPECIFICATION left by Cyprien Marie Tossié du Motay
at the Office of the Commissioners of Patents, with his Petition,
on the 4th December 1874.
I, CYPRIEN MARIE TESSIÉ DU MOTAY, of Lyons (France), Chemist,
do hereby declare the nature of the said Invention for "AN IMPROVED
MODE OF PREPARING OR TREATING SILK," to be as follows :—
My Invention relates to an improved process whereby baryta is sub-
stituted for the soaps heretofore employed in the boiling, scouring, and
bleaching of silk, and for fixing metallic oxides on silk.
It is well known that soaps generally, and in particular olive oil soaps,
have the property of scouring white and yellow silks, and of dissolving
the dull skin or coating with which the fibre is covered. It is also
known that silks thus boiled and scoured acquire their maximum lustre
and whiteness by the repeated action of sulphurous acid baths, either
liquid or gaseous.
Baryta acts chemically in the same manner as soap in boiling and
Scouring the silk, but in the case of yellow silks it only partially removes

page_text: the yellow colouring matter, and these therefore require t
either before, during, or after the scouring with an oxidizing agent,
followed by a liquid or gaseous bath of sulphurous acid.
In boiling white silks in a bath of pure water containing a solution
of oxide of barium, they acquire a whiteness and lustre which cannot
be obtained by the best soaps, such, that on removal from the bath they
do not require to be subjected to the action of sulphurous acid.
The yellow silks, in order to attain the same lustre and whiteness, must
first be treated in a soap bath, which dissolves the yellow matter, and
secondly in a bath of baryta, which completes the scouring and imparts
to the silk its maximum lustre and whiteness.
In carrying the above-described process into practice I proceed in the
following manner:-In a bath of distilled water, or of rain water, or of
water from which the sulphates and carbonates have been removed by
the addition of a salt of baryta, or of a small quantity of oxide of
barium, I dissolve a quantity of baryta equal to twelve per cent. of
the total weight of the silk to be scoured. The bath is then heated to
about 176° Fahr.; this temperature may be raised without inconvenience
to boiling point, but only during a few minutes; the proportion of
baryta may also be raised to fifteen per cent. without fear of injuring
the silk; but beyond this proportion the baryta might act too
energetically and deteriorate the silk. The bath of baryta having been
raised to the above-mentioned temperature, the silk is immersed therein
until the scouring is completed. The boiling is finished when the dull
skin or coating which covers the silk fibro has been entirely dissolved
and the silk attains a pearly appearance. On removal from the bath
the silk is thoroughly washed in soap and water, and is then plunged for
few moments in a bath of very dilute sulphuric acid, whereby it
acquires what is termed the "rustle" and the most perfect lustre.
I have also discovered that baryta has the property of decomposing
the salts of iron, manganesc, and tin, when combined with silks, and of
fixing the resulting metallic oxides upon the silks better than can be
effected by soaps. Thus the salts of iron employed in dyeing silks
black, when first combined with the silk, are decomposed by the oxide
of barium, which combines with the acid and fixes the metal in the
state of oxide. Thus also by a similar reaction the chlorides and per-
chlorides of tin, when combined with the silk, arc decomposed and the

page_text: stannous and stannic oxides remain united with the silk in the state of
a permanent combination. The last-named combinations have the
special and important property that without altering the appearance of
the silk or its property of assimilating colouring matters they cause it
to acquire a weight which may more than compensate for that which it
looses by the dissolving action of the soaps or of the baryta during the
process of boiling and scouring.