The objective of this experiment is to characterise four particular high-pressure polymorphs of various hydrates discovered by us in recent years during work carried out using the Paris-Edinburgh cell on PEARL/HiPr. At present, the crystal structures of these materials are unknown: our attempts at indexing and/or powder structure solution have been limited by either the low signal to noise ratio in the data at d-spacings longer than ~ 3.5 angstrom, or due to extreme sample texture. These high-pressure phases will be synthesised using the Paris-Edinburgh cell on PEARL/HiPr, quenched to liquid nitrogen temperatures and then recovered to atmospheric pressure for characterisation on the GEM diffractometer.