Molecular Biology - Basic Texts

[Carson]

Greetings
Can any one recommend an introductory text to the practicalities of
molecular biology, particularly reagent formulations, determining the
concentration of DNA by absorbance at 260, standard data eg extinction
co-efficients of dNTPs. Although I've gleaned much of the information
I need at present, I've found it scattered in various places or
acquired it from patient colleagues.  An introductory text would be
useful for acquiring first principles.
I'd be interested in hearing about favourite texts in this area.
Jeremy Carson