i06 
POPULAR SCIENCE REVIEW. 
platinum, which contained, in 100 parts — Platinum, 48-82 ; lead, 51-18 : 
corresponding to the formula Pt + Pb. This alloy has a specific gravity of 
15-77, is readily decomposed by mineral acids, but withstands boiling with 
acetic acid. 
MICROSCOPY. 
Death of the President of theRoyal Microscopical Society. — On December 12 
the Rev. J. Bancroft Reade, M.A., F.R.S., P.R.A.S., passed away from among 
us, at the mature age of seventy years. He might have lived much longer 
had it not been for the presence of a peculiar cancerous affection of the 
rectum, though, singularly enough, it was really a liver affection which 
removed him from among ns. He was a dear old man, and there must have 
been few who knew him who did not also love him. He was a man not as 
well known as he deserved to be, for during the last forty years he has been 
actively engaged in discoveries, both connected with the microscope and 
photography. A full sketch of his life will, we believe, appear in an early 
number of the “ Monthly Microscopical Journal.” Mean while a very good 
sketch of his photographic labours will be found in the “ British Journal 
of Photography ” of December 16. 
The Condition of the Microscope. — The question as to whether the object- 
glasses are perfect, or are in a condition very far from perfection, still goes 
on j Mr. Wenhani approaching the former side, Dr. Royston-Pigott the 
latter. The . controversy is not yet done, and in the present number of the 
“ Monthly Microscopical Journal,” we believe, a paper appears from Mr. 
Wenham, re-asserting his conclusion. As yet it is difficult to decide who is 
right. Time will tell. 
Mounting Diatoms. — This, it must be confessed, is seldom done rightly. 
In the u Monthly Microscopical Journal” for December a paper by 
Captain Lang gives some useful hints. He says that of course all 
diatoms should be mounted on the cover. To secure the correct centering 
of them, he forms on a glass slip, by means of the turntable, a ring of gold- 
size fths of an inch in diameter, the size of his covering glass, and within 
this a very minute one exactly in the centre. This is hardened by heat, as 
his cells are. On the outer ring, at equal distances, are placed three little 
bits of beeswax. The covering glass, on which it is intended to arrange the 
diatoms, is placed on this general mounting slip, and slightly pressed on the 
wax. Instead of distilled water, he places on the cover a very slight smear 
of glycerine, into which previously, as in the case of the water, a drop of 
gum may have been added. Into this the diatoms are dropped, and may 
then be pushed within the inner ring, and their perfect arrangement and 
centering are secured. The advantage of the glycerine over the water is 
that it is a greater solvent for freeing the diatoms from any extraneous dirt, 
and that it will remain moist for any length of time. When the arrange- 
ment is completed, the covering glass is gently pushed off the three pieces 
of wax, and transferred from the slide to the hot plate, when in a few 
minutes the glycerine is evaporated. Put on another slide under the micro- 
scope ; a drop of benzole is placed on the diatoms, and whilst they are being 
