A curaré, a drug distilled from the Amazonian umboltia, a species of massive vine which only grows along the upper reaches of the Amazon and Orinoco.
Yvette Bouvier, the butler Baines, Dr Hoxton Ryman, Winker Watson, Seaton Begg were all injected with CL14 by Marie LeVeaux. Other test subjects included Iain St Claire, the 7th Earl of Morn, the Hon. Arthur Price and Sir George Ogg who all received CL14 as part of their attempts at insurance fraud.
The main purpose of CL14 is to simulate death in the recipient by paralysing their organs but otherwise doing no harm. Essentially it puts the recipient into a state of hibernation, or 'suspended animation', but unless an antidote is eventually administered death will, in time, inevitably follow.
Although completely paralysed, the recipient's brain remains fully conscious throughout the duration of their 'hibernation' so they are completely aware of their surroundings but utterly unable to interact with it.
The antidote CL14X, itself distilled from the black narcissi flowers of Hayti, reverses the effects of CL14 but also has the 'side-effect' of slowing down the victim's natural ageing process, granting greatly increased longevity.