British Library MS. Sloane 3761. Paper. Duodecimo. 43 folios. 17th Century. 'Mullers process which hee gave too a noble Earle of Scotland under a severe oath of secrecy with a collection of other Authors which agreeing and confirming the same thing are collected and sett down as a proof to confirme his process for the makeing the white and red Elixir or L.P.'. ff.1-42.