less.

Peroxide of hydrogen is a weak oxidiser, and therefore, although (p. 035)
strong enough to destroy the colouring matter of the fibre is not
strong enough to decompose the fibre itself. Hydrogen peroxide is sold
as a water-white liquid, without any odour or taste. Its strength is
measured by the quantity of oxygen which is evolved when one volume of
the liquid is treated with potassium permanganate; the most common
strength is 10 volume peroxide, but 30 and 40 volume peroxide is made.
On keeping it loses its oxygen, so that it is always advisable to use
a supply up as quickly as possible.

Articles of all kinds can be bleached by simply placing them in a weak
solution of the peroxide, leaving them there for a short time, then
taking out and exposing to the air for some time. The best plan of
applying peroxide of hydrogen is the following: Prepare the bleaching
bath by mixing 1 part of peroxide with 4 parts of water. The strength
can be varied; for those goods that only require a very slight bleach
the proportions may be 1 to 12, while for dark goods the proportions
first given may be used. This bath must be used in either a wooden or
earthenware vessel. Metals of all kinds must be avoided, as they lead
to a decomposition of the peroxide, and therefore a loss of material.
To the bath so prepared just enough ammonia should be added to make it
alkaline, a condition that may be ascertained by using a red litmus
paper, which must just turn blue. Into the bath so prepared the
well-scoured goods are entered and worked well, so that they become
thoroughly saturated. They are then lightly wrung and exposed to the
air for some hours, but must not be allowed to get dry, because only
so long as they are moist is the bleaching going on; if they get dry
the goods should be re-entered into the bath and again exposed to the
air.

If one treatment is not sufficient the process should be repeated. The
peroxide bath is not exhausted, and only requires new material to (p. 036)
be added to it in sufficient quantity to enable the goods to be
readily and easily worked in the liquor. Any degree of whiteness may
be obtained with a sufficient number of workings. No further treatment
is necessary. It is found in practice that an alkaline bath gives the
best results.

Another plan of preparing the bleaching bath is to prepare a bath with
peroxide and water as before, then add to a sufficient quantity of a
solution of silicate of soda