Quince - 8-2-2005 at 01:53
This is very neat (look at the pictures with the brown stuff growing in the test tubes):
http://www.sas.org/tcs/weeklyIssues/2004-04-30/feature1/
I read of this experiment when I was about 12 in a very old book, and did the experiment as I found someone to give me potassium ferrocyanide. But
now I don't know where to find this reagent OTC. Any suggestions?
Esplosivo - 8-2-2005 at 02:24
Well I don't think it is a restricted chemical, at least I have bought the stuff through a chemical supplier. Nice 'experiment' though.
Would love to have a test-tube like that in my room - makes a nice decoration 
What ferrocyanide is used potassium ferrocyanide (II) or (III). From the rxn with Cu2+ I would suppose it is the Ferrocyanide (II) which is used. Am I
correct?
I am a fish - 8-2-2005 at 02:48
Some photographic suppliers sell it. Alternatively, you could convert potassium ferricyanide, which is available from many more photographic
suppliers:
If solutions of potassium ferricyanide and iron(II) sulphate are mixed, a redox reaction will occur and iron(III) ferrocyanide (AKA Prussian blue)
will precipitate out. Prolonged boiling of the precipitate in potassium hydroxide solution will convert this into potassium ferrocyanide and
iron(III) hydroxide. If a nominal excess of the iron(III) ferrocyanide is used, all the potassium hydroxide will react and so a pure solution of
potassium ferrocyanide can be obtained by filtration.
The_Davster - 8-2-2005 at 19:27
Will sodium ferrocyanide work instead of the potassium salt?
Oh well, I just tried it on 1/10 the scale presented on the site posted(with sodium ferrocyanide instead). Before adding the ferrocyanide to the
solution a couple of .5 mm prills of sodium hydroxide were added because the solution tested slightly acidic. Brownish film is forming on the bottom
around the pellet of copper sulfate and sugar a few seconds after being placed in solution.
Also would the pellet have to be completly dry for this experiment to work?
EDIT: I go back to the lab after posting this and a few little tendrils have started to grow, they currently are only a few millimeters long.
[Edited on 9-2-2005 by rogue chemist]
The_Davster - 13-2-2005 at 13:55
Leduc plants...Nah...Leduc fungus 
Thats what I get for using sodium ferrocyanide intsead of potassium ferrocyanide.
Quince - 13-2-2005 at 16:26
You should do a mix of the two...
Now if you could figure out a way to get different colors, you could grow a garden of the stuff 
I'm still having trouble finding ferrocyanide
[Edited on 14-2-2005 by Quince]