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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, 



