A NEW OR IMPROVED METHOD FOR MANUFACTURING SILK FROM THE BARK OF MULBERRY TREES
Year: 1876

page_text: PROVISIONAL SPECIFICATION left by Alexander Browne at the Office of the
Commissioners of Patents on the 26th August 1876. A communication from
abroad by Joseph Honoré Brunet, of Paris, France.
ALEXANDER BROWNE, of the Firm of Browne and Company, Patent Agents, of
5, Southampton Buildings, in the County of Middlesex. "A NEW OR IMPROVED
METHOD FOR MANUFACTURING SILK FROM THE BARK OF MULBERRY TREES." A
communication from abroad by Joseph Honoré Brunet, of Paris, France.
According to this Invention it has been discovered that the bark of the mulberry
tiee when not quite dry furnishes a large quantity of material which can be applied
to textile fabrics. But in order that this material shall be suitable for undergoing
the hackling and combing operations it must be quite disintegrated, that is, fieed
from the gummy matter in which the fibres are enveloped. For this purpose the
following process is employed:-The bark is peeled off, the branches annually
lopped off; this may be done by hand or by machinery, and the outside skin is
detached; the bark is then plunged into a hermetically closed vessel or bath, in
which is dissolved, say, 7 to 10 pounds of carbonate of soda per 100 pounds of bark
under treatment, all according to the size and consistency of the immersed bark.
The bath is made to boil for a sufficient time; one hour is sufficient in some cases,
but in general four hours will be found sufficient.
The removing of the outer skin is very easy when the bark is fresh, that is, from
about the 1st of April to the 15th of May, the time for pruning the mulberry tree;
but this operation is almost impossible when the material is dry.
The bark pieces are tied together in bundles, and subjected to boiling for an
hour or two in a bath containing clay; the outer skin can then be easily taken off
the bark. The material is then boiled in the alkaline bath, as above described, for
extracting the textile matter. When this has been obtained it is put for about two
hours in a pure water bath of about 195 degrees F., wherein the bulk of the saline
matter is left behind; the material is then steeped in a soap bath of about 195
degrees F. The material must be constantly stirred and turned over in order that
the liquid may thoroughly penetrate it, and take away the carbonate of soda
remaining, and also a large part of the gummy matter. The textile material is then
passed to a centrifuge or other exhauster, which draws off the liquid and dries the
textile material. In this condition the material will keep for any length of time.
This first part of the process, which I call the steeping is for obtaining the fibrous

page_text: material which is contained in mulberry tree bark, and this material can then be
prepared for spinning.
Carbonate of soda has been mentioned above as the alkali herein employed, other
alkaline salts may however be employed, such for instance, as the salts of potassa.
The employment of soap or soapy wood, such as Panama wood is also reserved.
A preliminary steeping of the bark may be effected by means of running water,
as for hemp and flax. In that case the bark must be so treated for a sufficiently
long time, and be dried on the turf, and then submitted to a squeezing and beating
process in order to disengage the fibres. This mode of treating has also been found
successful.
The material may then be further treated by the alkali bath as described.
The bark of the mulberry tree furnishes an abundance of fibre, but it is opaque.
The following is a mode of giving it the appearance and properties of silk-The
material on coming out of the centrifuge is plunged into another soap bath, heated
to about 195° F. for a length of time, similar to that of the aforesaid steeping; the
material is then strained, and plunged into another bath of about the same
temperature, but containing about one third less soap than the previous bath; this
latter bath also contains lard, grease, or animal or vegetable oil in varying
proportions, according to circumstances. The material removed therefrom is then
washed in two weak baths of soap water, heated to about 212° F., the effect of
which is to remove the fatty parts, and to dissolve the gum, which remained and
hid the true silky aspect of the fibre; the fibres are then dried in the centrifuge
boiling water being poured over them at different times during this operation. The
silk thus obtained must be dried in the shade, and shaken from time to time; it can
then be prepared for spinning.