82 GuYj on preserving Microscopic Objects in Tubes, 
Canada balsam, glycerine, castor oil, or other liquids, though 
I can conceive it to be quite easy to draw these liquids into 
the tubes, without admitting air into them, and then sealing 
them securely by Brunswick black. I must be understood, 
however, to recommend the preservation and mounting of 
objects in tubes chiefly as superseding the necessity of using 
any of these liquids for preserving the objects. The exclusion 
of air and moisture by sealing the tubes at both ends answers 
every purpose of preservation, and most purposes of display. 
I have placed under the microscopes at the side table, 
specimens of objects mounted in round and flat tubes, and 
also on the table several other specimens — some chemical, 
others belonging to the several divisions of natural history — 
seeds, pollen, and other portions of plants, antennae and legs 
of insects, portions of the wing-cases of beetles, &c. 
The objects which I have placed under the microscopes 
are — 
1. A stamen of the rhododendron in a round tube. This 
is a very beautiful transparent object consisting of a long 
cylindrical axis with jointed spokes radiating from it. It has 
been now enclosed in the tube about nine months, and is as 
fresh and clear as when first inserted. It has undergone no 
change itself, nor is the tube dimmed in the least degree. 
2. Crystals of arsenious acid, in a flat tube, being an ordi- 
nary specimen of the sublimed acid. The surface of the glass 
is apparently flat, and the specimen as distinct in every way 
as if obtained on a flat surface, and covered wdth a flat micro- 
scopic glass. 
3. Arsenite of zinc, in a round tube. My colleague^ Pro- 
fessor Bloxam, has kindly allowed me to exhibit this curious 
salt, in anticipation of a paper he is about to read at the 
Chemical Society. It consists of small pellucid, and large 
opaque, globular masses. The smaller ones cohere some- 
thing after the fashion of bunches of white currants, and 
the larger ones show a similar tendency to cling together. I 
have placed them under the binocular microscope, for which 
they form a very appropriate object. Though there are one 
or two other minerals and chemical compounds which assume 
the same globular form, it is believed that this substance 
will prove unique as an object for the microscope. 
