EXPERIMENTS IN MOUNTING THE AMPHIPLEURA PELLUCIDA. 125 
gee but failed. Mr. C. Watt kindly made me a small quantity 
m some crude india-rubber which I supplied him with. 
eying again and again I did not get an better results, in fact not 
so good as from the thymol. I gave it up in despair, determined 
to abandon the sulphur in future. However, sulphur as a moun 
m 
size of nalf a small pea, melted it on the end of a glass slip, and 
having trimmed to a point a wooden lucifer match I dipped it into 
the caoutchine and then stirred it well into the molten sulphur. 
I then held the slide over the flame of the spirit lamp, gently tilting 
the slide to cause the sulphur to flow into position a little out of 
centre ; I then brought the heat up to ignition of the sulphur, the 
flame was immediately blown out andthe upper surface of the edge 
of the cover-glass gently passed over the surface of the sulphur, 
skimming off all the burned carbonaceous products which had 
formed on the surface of the melted sulphur, the cover-glass placed 
in position, and the air-cells gently tapped out from under the 
pressure until the sulphur hardens outside the cover-glass. 
hazy or any crystallization form, this is owing to a 
still retained under the cov er-glass ; remelt, tap the air-cells out and 
press as before. I find t at two or three remelts are quite sutti- 
cient to get rid of all the air-cells and to make the slide permanent. 
The secret is that whatever hydro-carbon is used heat must be 
peeved ae to decompose it, and no more hydro-carbon than 
th ct quantity must be used. B 
“ees r and selenium.—The same treatment as for the sulphur, 
but the selenium is so dirty it is impossible to have a clean mount. 
Silver film.—This process, so far as the silver deposit is 
concerned, I made known to you in November last ; the one 
evening Dr. A. Y. Moore’s, of America, slide sent me in exchange 
for one of mine, You will see that his process and mine are two 
distinct methods, 
onobromide of napthaline.—This medium used to serve me in 
the same way as the lia: of iakeeen, the diatoms getting 
completely spoiled by the globules forming over and around them. 
By adding 3 grains of salicylate of chinoline 9 the dram of the 
monobromide this separation is prevented. I suppose its action 
is by taking up the moisture which may be held in suspension by 
