24 Profs. W. B. and R. E. Rogerson the, &c. 
2. A solution containing | part in 2000 produced the pellicle 
in distinct spots and not continuous as in the former case. At the 
same time the liquid became of a deep greenish purple color, and 
although only one quarter of an inch thick was nearly opaque. 
3. A solution of 1 part in 10,000 gave no adherent pellicle, but 
on continuing the heat for two or three minutes became strongly 
colored, presenting a deep greenish purple by transmitted, ant a 
dull olive by reflected light. 
A. In a solution of 1 part.in 20,000, ddiomecelnuieunmtliciet 
ple tint was still quite decided, and even when the solution was 
diluted so as.to contain only ,;1,,;th of nitrate of silver this 
color was very distinctly manifested after heating it sometime 
with aldehydite. Compared with the faint opalescence caused 
by the addition of chloride of sodium to the same solution, this 
effect of the ee compen to ‘be the more apetone of the 
two. 
lish tint (theliquid, marked in these exner. 
rl, 
The pecul experi 
ments, s evide ionily due to the finely divided 1 metallie silver held in 
suspension, and. affords therefore a striking confirmation of the 
statement of Dupasquier, that not only gold, but silver and other 
opaque bodies, present this hue when greatly subdivided and 
viewed through a clear suspending medium, (Comp. Bends Bio. 
1, July, 1845.) It may be added that the 
when a very: dilute solution of nitrate of silver i ds subjected to the 
reducing action of a formiate. we 
Allusion has already been made to se scRigtian of. hediedtseid 
in large amount by a modification in the above process. For this 
purpose the powdered bichromate and the sulphuric: acid -in ‘the 
proportion of about 2 to 3, are to be first mixed in the retort so as 
to develop a large amount of free chromic acid. The alcohol is 
then introduced from the pipette as in the former case and with 
like precautions. During the violent action that ensues, much - 
acetic acid passes over without the aid of external heat. When 
‘the alcohol thus added amounts to about twice the weight of the 
bichromate employed, the action having. subsided, we apply a 
gentle lamp heat and obtain a large additional quantity of the 
acid. This we have found to be free from sulphurous acid and 
enn neon ai ae 
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