<P> Eventually, one of the chemicals used in the serum ran low, and subsequent batches prepared from new stocks failed to work . Jekyll speculated that one of the original ingredients must have some unknown impurity that made it work . Knowing he would become Hyde permanently, Jekyll decided to write his "confession". He ended the letter by writing, "I bring the life of that unhappy Henry Jekyll to an end ." </P> <Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2012) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section does not cite any sources . Please help improve this section by adding citations to reliable sources . Unsourced material may be challenged and removed . (December 2012) (Learn how and when to remove this template message) </Td> </Tr> <P> Dr Jekyll is a "large, well - made, smooth - faced man of fifty with something of a slyish cast", who occasionally feels he is battling between the good and evil within himself, upon leading to the struggle between his dual personalities of Henry Jekyll and Edward Hyde . He has spent a great part of his life trying to repress evil urges that were not fitting for a man of his stature . He creates a serum, or potion, in an attempt to mask this hidden evil within his personality . However, in doing so, Jekyll transpired into the smaller, younger, cruel, remorseless, evil Hyde . Jekyll has many friends and an amiable personality, but as Hyde, he becomes mysterious and violent . As time goes by, Hyde grows in power . After taking the potion repeatedly, he no longer relies upon it to unleash his inner demon, i.e., his alter ego . Eventually, Hyde grows so strong that Jekyll becomes reliant on the potion to remain conscious . </P>

The strange case of dr jekyll and mr. hyde