Haemalchemy is a book that gives details on what the Vampyres are experimenting with. It must be telegrabbed in the lab to be obtained. It is given to Safalaan at the end of the Darkness of Hallowvale quest.
Haemalchemy, when broken down by definition, is the study of transmuting or modifying blood.
If a player attempts to read the book on Halemalchemy, they will get the message, "This book seems far too complex to you at the moment." As such, the exact contents of the book are a mystery.