The points referred to were the apparently unimportant details which
often contribute so much to the ease and pleasure of working. First,
the use of square pieces of felt, such as are used under beer glasses
in saloons, for setting hot beakers and flasks on to prevent chilling
and consequent cracking. Second, in crystallizing substances for
examination under the microscope; one watch glass is placed upon
another with the substance between them, and the upper glass filled
with ether, the cold produced by its evaporation hastening the
crystallization. Third, removing precipitates and solid matter from
flasks, by heating to boiling, and inverting in a vessel of water.
Fourth, crystallization by gradual dilution. Fifth, filter paper
without ash. In German laboratories it is customary to dissolve out
the mineral matter from white filtering paper by washing in dilute
hydrochloric and hydrofluoric acids. Sixth, the use of infusorial
silica for drying purposes. Being very porous, it will absorb five
times its own volume of water. If a filter paper, holding a wet
precipitate, be placed upon a layer of this earth, it will become
quite dry in a very short space of time. Mr. Austen also remarked that
substances retain their heat for several days when placed in cork
boxes. To keep a substance air-tight, it may be placed in a flask, the
neck painted with a solution of india rubber in chloroform, and a
plate of glass laid upon it. The solvent quickly evaporates, leaving a
delicate film of rubber, which holds the glass tightly in place.
The next meeting of the Chemical Section will be held February 12; of
the Mineralogical Section, February 19.
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