' s ▁existing ▁stock ▁and ▁in ▁ 2 0 0 0 ▁took ▁delivery ▁of ▁a ▁ 5 . 5 - ton ne ▁dies el - power ed ▁rep lica ▁tank ▁engine . ▁The ▁line ' s ▁original ▁equipment ▁was ▁purchased ▁by ▁the ▁W alth am ▁Ab bey ▁Royal ▁Gun pow der ▁M ills ▁museum ▁at ▁W alth am ▁Ab bey . ▁ ▁Lo comot ives ▁ ▁See ▁also ▁ ▁British ▁narrow ▁gauge ▁rail ways ▁ ▁References ▁ ▁External ▁links ▁B ic ton ▁Wood land ▁Railway ▁ ▁Category : 1 8 ▁in ▁gauge ▁rail ways ▁in ▁England ▁Category : T our ist ▁attra ctions ▁in ▁Dev on <0x0A> </s> ▁Cob alt ▁hyd ride ▁is ▁an ▁in organ ic ▁comp ound ▁with ▁a ▁chemical ▁formula ▁Co H 2 . ▁It ▁has ▁dark ▁grey ▁cry st als . ▁It ▁ox id izes ▁slowly ▁in ▁air ▁and ▁react s ▁with ▁water . ▁ ▁Two ▁forms ▁of ▁c ob alt ▁hyd ride ▁exist ▁under ▁high ▁pressure . ▁From ▁ 4 ▁to ▁ 4 5   G Pa ▁there ▁is ▁a ▁face ▁cent red ▁cub ic ▁form ▁with ▁formula ▁Co H . ▁This ▁can ▁be ▁decom pressed ▁at ▁low ▁temper atures ▁to ▁form ▁a ▁met ast able ▁comp ound ▁at ▁atmos pher ic ▁pressure . ▁Over ▁ 4 5   G Pa ▁a ▁c ob alt ▁di h yd ride ▁Co H 2 ▁also ▁cry st all ises ▁in ▁a ▁face ▁cent red ▁cub ic ▁form . ▁ ▁Pre par ati om ▁Cob alt ▁hyd ride ▁can ▁prepared ▁by