Process for separating Silver and Copper. 235 
I have been induced to send you this account, not having met 
with any one in your Magazine, and with a wish that some of 
those persons who saw any extraordinary appearance in the look 
of the sun that morning, will communicate their observations to 
you, stating the ¢ime and place where they observed it. 
Walthamstow, Essex, 14th September, 1821. B. M. Forster. 
LITHOGRAPHY. 
An experiment has lately been made to take off impressions 
from plants by lithographic printing, which, although it did not 
succeed so well as was desirable, leaves little doubt but this me- 
thod may prove of considerable use to botanists. 
A specimen of Silthorpia eurcpcea, which was gathered several 
years ago in Cornwall, was, we understand, covered with lithogra- 
phic ink, and impressed on the stone, from which several impres- 
sions were taken. There is a well-known method made use of 
for taking impressions of the leaves of vegetables by covering 
them with printers’-ink, and then impressing them on paper. 
The benefit likely to arise from impressing plants on stone, is 
owing to the facility of multiplying copies much more accurate in 
some respects than a drawing can be expected to be. 
ECONOMICAL PROCESS FOR SEPARATING SILVER AND COPPER. 
Dissolve the alloy in nitric acid, and evaporate the solution to 
dryness, in a glass vessel. Place the salt in an iron spoon over 
a moderate fire, and keep the mixture in fusion till it entirely 
ceases to afford bubbles, when itis to be poured out upon an oiled 
plate. To be certain that all the nitrate of copper is converted 
into the black oxide of copper, dissolve a small portion of it in 
water, and test it with ammonia. If the solution, which ought 
to be at first clear and limpid, does not acquire the slightest 
shade of blue, it may be concluded that the nitrate of silver ob- 
tained is quite free from copper. If not so, the fusion must be 
continued a few seconds longer. The black product is to be 
dissolved in cold water; and the solution being filtered, the nitrate 
of silver passes through in a state of purity. By washing the 
oxide which remains upon the filter, the small portion of nitrate 
of silver with which it may be impregnated will be removed ; 
the oxide is then to be dried. The nitrate of silver is afterwards 
treated differently, according to the use to which it is to be 
applied. 
This process is more simple, expeditious, and accurate, than 
the common method of separating silver from copper by the hu- 
mid way. 
Gg 2 FISH 
