Bauhaus-Universität Weimar

The Art of Projecting. A Manual of Experimentation in Physics, Chemistry, and Natural History with the Porte Lumière and Magic Lantern
Dolbear, A. E.
Nearly fill the tank with water and add a few drops 
of blue litmus solution ; then dip a glass rod into a 
weak acid solution of any convenient kind and gently 
stir the litmus solution with it : it will turn red in the 
neighborhood of the rod. After washing the rod, dip 
it into an alkaline solution of ammonia or potash, and 
again stir the solution in the tank. Blue clouds will 
form in the red sky upon the screen until the whole is 
again a beautiful blue. 
In place of litmus solution use a solution made by 
boiling purple cabbage. Acid turns this red, and an 
alkali turns it green. Such changes may be effected a 
number of times in succession in the same solution. 
Nearly fill the tank with sulphate of soda, in which 
is put either litmus or cabbage solution to color it ; the 
latter is the best. After projecting it as a blue solu¬ 
tion dip the terminals of a battery of three or four 
cells into it. Decomposition will begin and the acid 
and alkaline reactions will be observed about the poles. 
Fill the clean tank nearly full of pure water and add 
a drop or two of a solution of nitrate of silver and stir 
it well. Then dip the glass rod into very dilute hydro¬ 
chloric acid. Very dense clouds of chloride of silver 
will form and fall to the bottom of the tank. Add a 
few drops of strong ammonia water, and the cloudy 
solution will again become clear. 
A small piece of carbonate of lime or of soda placed 
in the tank containing a very dilute solution of hydro¬ 
chloric acid gives up its carbonic acid in apparently 
large quantities


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