DE SILICIFICATION

476. Chloride of Calcium for Bleaching (Paul 11fayer's
method').-This is a process imagined for the purpose of
getting rid of the blackening that often occurs as a conse-
quence of over-staining by osmic acid.
The specimens are put into alcohol (either of 70 or 90 per.
cent). Crystals of chloride of calcium are added until the
bottom of the vessel is covered with them. A few drops of
concentrated hydrochloric acid are then added by means of a
pipette, and mixed-in by shaking the vessel as soon as the
green colour of the evolving chlorine has begun to show itself.
Warm if necessary; but most objects, even large ones, may be
bleached in half a day without the employment of heat. The
tissues do not suffer.
Instead of hydrochloric acid, nitric acid may be used; in
which case the bleaching agent is the freed oxygen, instead of
chlorine.
The first method may be used for the purpose of removing
pigment from the eyes of insects.
477. Chlorine Bleaching Process (Marsh's method 2).-Marsh
generates chlorine in a small bottle by treating crystals of
chlorate of potash with strong HCI, and leads the gas (by
means of a piece of glass tubing bent twice at right angles)
to the bottom of a bottle containing the sections in water.
(See a fig. of the apparatus in 'Journ. Roy. Mic. Soc.,' iii
(1880), p. 854.)
478. Chlorine Solution (Sargent's method 3).-Hydrochloric
acid, 10 drops; chlorate of potash, - dr.; water, 1 ounce.
Soak for a day or two. Wash well.
This method is intended for "bleaching insects;" it will
be seen that it is only applicable to the preparation of hard
parts as soft tissues would be destroyed by the solution.
479. Chloride of Lime; Chlorinated Soda.-These and
1 ' Mitth. Zool. Stat. Neapel.,' ii (1881), p. 8.
2 'Section Cutting,' p. 89.
3 ' Journ. Roy. Mic. Soc.' (N.S.), iii (1883), p. 151.

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