Description Ferrofluid in the bottle
How the liquid iron gets into the bottle and what magnetism has to do with it, we may need to explain first. Ferrofluid, which we also offer as a pure liquid, is a solution with nano-iron particles. Just like the iron filings you know from physics class, this substance also reacts to magnetic fields. However, the liquid forms that emerge are much more impressive than the clusters of filings that typically form on the teacher's desk. ;)
Ferrofluid in the bottle goes a step further by embedding the iron particles in a clear liquid and corking it. This way, gravity interferes less with your experiments. If you hold the included magnet (with a practical handle) against the glass from the outside, you can observe how the ferrofluid aligns itself in the magnetic field. Astonishing spiky structures emerge. Change the shape by moving the magnet closer or further away. Although only one magnet is included, you can of course use a second, third, fourth... magnet to form new structures, let the ferrofluid flow back and forth, or just swirl it around a bit.
Three different colors are available: Black, Blue, and Gold. Who wouldn't want a bit of liquid gold in a bottle? ;) Besides choosing the color, there are a few points to consider: First, you should not leave the magnet on the bottle when you are not experimenting with it, as the ferrofluid could leave stains on the glass if it adheres for a long time. You can simply place the corresponding magnet on the bottle cap, where it is far enough away. Also, you should never try to open the bottle - which is very difficult anyway - as ferrofluid causes nasty stains. Of course, the contents of the bottle should not be consumed... Since the ferrofluid in the bottle includes a strong neodymium magnet and there is always the risk of shards or leaking fluid, a bit of caution is required when experimenting. This does not mean, however, that you can't have a lot of fun with it. :)
By the way, ferrofluid was not only developed to entertain us and make physics classes a bit more enjoyable, but it also has practical uses and is used, for example, in hard drives, speakers, and MRIs. There are also attempts to use ferrofluids in cancer detection and therapy. So you're bringing home a fantastic all-rounder that is simply fun.
