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contain sufficient indications whether the specimens deserved 
further attention. 
The Secretary read a letter from Mr. Joseph Sidebotham, 
accompanying a specimen and a drawing of the Aulacodiscus 
formosus, showing the four projecting knobs or handles visible 
upon that diatom. Mr. Sidebotham states that in all draw- 
ings hitherto published, these protuberances appear like simple 
elevations or bosses, nor could they be seen otherwise until 
the binocular microscope revealed their true shape. Mr. 
Dancer first called his attention to this peculiarity. 
Mr. Crompton exhibited, and presented to the members, 
specimens of capillary tubes used by him to collect and pre- 
serve fluids for microscopical examination for medical purposes. 
Mr. Crompton has used such tubes for more than a year, and 
has preserved specimens of blood, urine, &c., which by any 
other method would have spoiled. The main feature consists 
in hermetically sealing the tubes after the introduction of the 
fluid, by holding their ends alternately in the flame of a 
candle or lamp until the glass melts, and the orifice closes ; 
the tubes may be about three-fourths filled by capillary 
attraction or immersion, and care must be taken not to allow 
the fluid to approach the hot end of the tube whilst being 
sealed. The Edinburgh vaccine tubes answer the purpose 
well ; they may be about three inches long, and a number of 
them may be carried in a small pocket case at all times ready 
to be filled. When required for examination, the tube is 
broken, and the enclosed fluid placed under the microscope. 
The Secretary exhibited a specimen of the compound 
salt of magnesia and copper, prepared by Mr. Thomas Davies, 
of Warrington. Doubts having been expressed if it were a 
true compound salt, or a mere mechanical mixture, Mr. Dale, 
who at the Secretary’s request had prepared some of the salt, 
