Procedure modified by Jonathan Breitzer and George Lisensky from
"Preparation and Properties of an Aqueous Ferrofluid" by
Patricia Berger, Nicholas B. Adelman, Katie J. Beckman, Dean J.
Campbell, Arthur B. Ellis, and George C. Lisensky, J. Chem.
Educ., 76, Ferrofluids are colloidal suspensions of magnetic
nanoparticles. Ferrofluids respond to an external magnetic field
enabling the solution's location to be controlled through the
application of a magnetic field. Fe3O4 magnetite nanoparticles
can be produced by mixing Fe(II) and Fe(III) salts together in a
basic solution. The particles must remain small and separated
from one another in order to remain suspended in the liquid
medium. Surfactants are used to prevent the nanoparticles from
approaching one another too closely. Once prepared, ferrofluids
have the captivating property of exhibiting "spikes" when placed
in the proximity of a strong magnet. Ferrofluids can be messy.
The particular ferrofluid you will prepare will permanently
stain almost any fabric.