The article is titled "Catalogue of Eighty-Seven Public Friends yt have Died in Pennsylvania since ye First Settlement of Friends there Read at ye Yearly Meeting, 1709". The prologue states that it was originally published in two parts in Quaker History in 1913-1914--so they're public domain at the JStor links below!
part 1
“A CATALOGUE OF ‘EIGHTY-SEVEN PUBLICK FFRIENDS YT HAVE DYED IN PENSILVANIA SINCE YE FIRST SETTLEMENT OF FRIENDS THERE.’” Bulletin of Friends’ Historical Society of Philadelphia 4, no. 3 (1912): 140–47. http://www.jstor.org/stable/41944902.
part 2
“A CATALOGUE OF ‘EIGHTY-SEVEN PUBLICK FFRIENDS YT HAVE DYED IN PENSILVANIA SINCE YE FIRST SETTLEMENT OF FRIENDS THERE.’ [Continued].”
Bulletin of Friends’ Historical Society of Philadelphia, vol. 5, no. 1, 1913, pp. 14–19.
JSTOR,
http://www.jstor.org/stable/41944919. Accessed 6 Sep. 2022.
Thomas Mercer is in part 2, page 16 (which is page 120 of the Pennsylvania Genealogical Magazine reprint; I confirmed they are the same entry.)
"Thomas Mercer of Andover in ye County of Wiltshire. He arrived about ye year 1682 or 1683 and died in ye year 1694."