58 Double Staining of Wood, &c. By G. D. Beatty. 
mortar for about ten minutes two drachms of ground campeachy 
wood with one ounce of absolute alcohol, setting it aside for twelve 
hours, well covered, triturating again and filtering. Ten drops of 
this are added to forty drops of a solution of alum ; twenty grains 
to the ounce of water. After one hour the mixture is filtered. 
Into this the section, previously soaked in alum-water, is placed 
for two or three hours, or until dyed of a moderately dark shade. 
When dyed of the depth of shade desired, which is determined by 
dipping it in alum-water, the section is successively washed for a 
few minutes each, in alum-water, pure water, and 50 per cent, 
alcohol. Finally it is put in absolute alcohol until transferred to 
the blue. 
Carmine and aniline blue produce marked stainings, but they 
are rather glaring to the eye under the glass. I use an ammoniacal 
solution of the former, double the strength of Beale's, substituting 
water for glycerine. In this a section is kept for several hours. 
On removal it should be dipped in water, and then put for a few 
minutes in alcohol acidulated with 2 per cent, of nitric acid ; then 
in pure alcohol ; then in the half-grain blue solution before spoken 
of, from which it should be removed to alcohol; then to oil of 
cloves. Much colour will be lost in the acid alcohol. The acid 
is to neutralize the ammonia, which is inimical to aniline blue. 
Magenta aniline or haematoxylon may be used with green instead 
of blue aniline. The brand of green I prefer is the iodine brand, 
one grain to the ounce of alcohol. 
Double stainings of sections of leaves in which red is first used 
have the spiral vessels stained this colour, other parts being purple 
or blue. Kadial and tangential sections of wood have the longitu- 
dinal woody fibres red, and other parts purple or blue. 
This selection of colour is, I think, due to the fact that spiral 
vessels and woody fibres take up more red than other parts, and are 
slower in parting with it. The blue, therefore, seems first to over- 
come the red in parts where there is less of it. It will entirely 
overcome the red if sufficient time be given. 
If the blue be used before the magenta aniline, the selection of 
colour is reversed. 
I would here call special attention to the importance of examin- 
ing these stainings at night, as the red in them has a trace of blue in it 
which does not show at that time, but comes out so decidedly by day- 
light, as to change, even spoil, the appearance of the specimen. 
I think they should be mounted in Canada balsam, softened 
with benzole, as the presence of the latter may be beneficial in pre- 
serving its magenta. 
I would offer a few words upon section-cutting, and upon pre- 
paring sections for dyeing. 
To cut a thick leaf, place a bit of it between two pieces of potato 
