"The Proprietors" = Robert Dickinson and his father-in-law Thomas Vincent, who here publish Gowland's work as "found among other MS. papers after his death" (p.11), with an advertisement for their version of "Gowland's lotion" at the end
This work is not mentioned in an early printing of a work by the same proprietors, A parlour companion ... And description of ... Gowland's vegetable lotion (dateable to between Oct. 1793 and June 1794); but it is in a slightly later version of the same, printed after Vincent's death (date unknown)
The publishing firm Murray became Murray and Highley 1794-1803 (Ian Maxted, The London book trades 1775-1800, 1977, p.159)
Copy 1 Supplier/Donor: Found Note: Photocopy only. From Sion College Library copy. Unbound