128 EXPERIMENTS IN MOUNTING THE AMPHIPLEURA PELLUCIDA, 
oe of chromium was the red brownish deposit which 
eR around the diatoms after mounting ; that this 
hte 
with the organic matter of the mounting pean The effect was 
the same whether I used orcinol, valerianate of quinine, or piperine, 
and when the deposit was in excess a burned or charred appear- 
‘Since the above experiments were made I have obtained a small 
vn rd of chloro-chromic acid, a highly volatile liquid, giving off 
fumes when exposed to the atmosphere. On using it as a 
liquid medium it is of no value. On holding a prepared cover- 
glass over the mouth of the vial containing this liquid a slight 
watery film is deposited, and on mounting the cover-glass I got the 
by itself. This preparation I look upon as one of the most 
valuable of the series. By regulating the amount of deposit on 
the cover-glass the colouration may be given from a deep brown 
to an almost imperceptible tinge, and if necessary the cover-glass 
can be ba cern and remounted ou another slide without damaging 
the prepara 
Chloride ee tin.—In relating the method of manipulating this 
salt it will suffice for a description of the major part of the others. 
I had already tried this agent as a liquid medium, and discarded it 
as of no value. 
On placing a small portion on the mica slip and subjecting it ‘6 
heat, dense fumes mixed with the water of <r Aare are given 
off ; and when only a clear liquid is left behind still giving off white 
fumes, the cover-glass is held in position nrg a pair of. forceps to 
intercept the fumes, a white deposit is immediately formed, and 
the moment a sufficient quantity is deposited the cover-glass is 
withdrawn and held over the heated mica until resublimation 
takes place, leaving a metalic “scud” on the cover-glass. en 
mounted in piperine, if roperly managed the diatoms will be found 
lying in a film of chloride of tin, the “striee beautifully defined, of 
a steel-grey lustre, and around the e ge of the valve a golden 
yellow tinge. I think the definition quite up to the phosphorus 
mounts. Being a deliquescent salt it must be mounted when hot ; 
if not, moisture will be again absorbed and the slide will be found 
to be worthless when mounte 
Chloride of lead. —Sublimed in the same way it runs the cbloride 
of tin pretty close, the same steel-grey lustre and the golden 
vera tinge surrounding the diatoms. The chloride of Sead is not 
eliquescent, consequently more manageable 
- Chloride of re rad cxinascel ye handirn as the butter of | 
antimony. A drop or two of this preparation is gently evaporated 
: “uecmiee until all moisture has disappeared, 1 ‘then ne 7. 
