我不大清楚这是什么，怎么弄出来的，看看有没人知道。或许有磁铁在里面吧。
板凳~ 
好神奇啊～～～！！！
A ferrofluid (from the Latin ferrum, meaning iron) is a liquid which becomes strongly polarised in the presence of a magnetic field. It is a colloidal mixture comprising extremely small magnetic particles suspended in a synthetic oil. The particles are coated with a soap or detergent to prevent them from clumping together.
Ferrofluids are composed of nanoscale ferromagnetic, or ferrimagnetic, particles suspended in a carrier fluid, usually an organic solvent or water. The ferromagnetic nano-particles are coated with a surfactant to prevent their agglomeration (due to van der Waals and magnetic forces). Although the name may suggest otherwise, ferrofluids do not display ferromagnetism, since they do not retain magnetization in the absence of an externally applied field. In fact, ferrofluids display (bulk-scale) paramagnetism, and are often referred as being “superparamagnetic” due to their large magnetic susceptibility. Permanently magnetized fluids are difficult to create at present.
长见识了~~
神奇啊.