A small cylinder of hydrogen fluoride with 340 g or 360 liter of HF in it. More than enough to kill someone.
Hydrogen fluoride is a colorless gas what can be liquefied quite easily, with a little ice and water, since its boiling point is 19.5 °C. The gas or its solution in water (hydrofluoric acid) attacks glass, so it could be only stored in steel or plastic. The reaction with silicates (glass) produces silicon tetrafluoride what is a low boiling point ( 4 °C), highly reactive compound and hexafluorosilicic acid.
SiO2 + 4 HF → SiF4(g) + 2 H2O
SiO2 + 6 HF → H2SiF6 + 2 H2O
Hydrogen fluoride is the only hydrohalic acid that is not considered a strong acid, i.e. it does not fully ionize in dilute aqueous solutions. When the concentration of HF approaches 100% (like in the gas cylinder on the picture), the acidity increases dramatically because of homoassociation: 3 HF is in equilibrium with H2F+ + FHF−
Once absorbed into blood through the skin, it reacts with blood calcium and may cause cardiac arrest. In the body, hydrofluoric acid reacts with the ubiquitous biologically important ions Ca2+ and Mg2+. Hydrofluoric acid exposure is often treated with calcium gluconate, a source of Ca2+ that sequesters the fluoride ions. So if anyone works with this, always have a lot calcium gluconate solution somewhere close.