99 
MICROSCOPICAL SECTION. 
March 16th, 1863. 
Mr. Joseph Sidebotham, Vice-President of the Section, in 
the Chair. 
Mr. Watson presented specimens of Jungermannia tomen- 
tella and asplenoides, collected on Baguley Moor. 
Mr. Sidebotham presented specimens of the following 
mosses, in fruit : Fissidens exilis, Fissidens adiantoides, 
Grimmia pulvinata, Weissia controversa, Brynm atropur- 
pnreum, &c., in a good state for microscopical examination. 
Mr. J. G. Dale, F.C.S., presented a specimen of crystal- 
lised film of picrate of aniline ; and in a note to the Secretary 
explained his method of preparation from picric acid and 
aniline. The equivalent of picric acid is 229 ; that of aniline 
is 93 ; and when dissolved in strong alcohol in those propor- 
tions by weight, mixed and set aside, the picrate of aniline 
will crystallise in yellow needles. The film for the micro- 
scope is formed from a solution of these needles in absolute 
alcohol, a drop of which being spread over a clean hot glass 
slide, the crystallised film is at once produced by the rapid 
evaporation of the alcohol, if the slide he at the proper degree 
of heat, which can only be found by repeated trials. If too 
hot, the salt will melt and become partially decomposed ; if 
not hot enough, it will he crystallised in needles, or be 
deposited as an amorphous film. When properly crystallised, 
circular radiated discs will appear with more or less regularity, 
showing with the polariscope very brilliant colours, and a 
black cross in the centre. The crystallised films may be 
mounted in new soft balsam ; but a mixture of chloroform 
and balsam dissolves them immediately. 
