Magnetisation of a plain fluid

Can plain water, or the HHO off a cell, be magnetised by the coil — and how much?

M = χ \cdot H, \qquad ΔB = \mu_0 \cdot M

Method

1. Look up the medium's volume susceptibility at 20 °C and one atmosphere: −9.0 × 10⁻⁶ for water, +1.8 × 10⁻⁶ for oxygen, +6.0 × 10⁻⁷ for the two-to-one hydrogen–oxygen mix off a cell, −2 × 10⁻⁹ for hydrogen alone.
2. For a gas, scale the susceptibility with the pressure in atmospheres: twice the pressure is twice the molecules and twice the response. A liquid's density barely changes with pressure and its susceptibility is taken as fixed.
3. Multiply by the applied field for the magnetisation, in amperes per metre — the same unit as the field, so the susceptibility is simply the ratio.
4. Multiply by μ₀ for what the medium adds to the flux density. Against the coil's own μ₀H it is the susceptibility again: parts per million.
5. Compare with a 5 % slurry of micron iron in the same field, which is demagnetisation-limited to about 0.15 H — the ratio is what "plain water" costs.

Assumptions

• Linear response, M = χH, which holds for every diamagnet and for a paramagnetic gas at any field a coil can make: oxygen at room temperature is nowhere near saturating below hundreds of tesla.
• Handbook susceptibilities at 20 °C. A paramagnet's falls as 1/T (Curie's law) and a diamagnet's does not change; neither moves enough to matter here.
• A gas at pressure is an ideal gas: density and susceptibility proportional to pressure. Good to a per cent or so up to tens of bar.
• No particulate at all. The moment any iron is in the tube this page is the wrong one, and the medium-susceptibility calculation is the right one; the two differ by four orders of magnitude at 5 % loading.
• Nothing here is Meyer's. The estate material describes a medium in a tube and does not say what it is; the question "could it just be water, or the gas off the cell" is the archive's, and this is the arithmetic that answers it.