Merchin?

No doubt brought up on rhymes for children like this

Maesyfed, yma safwn,

wrth ddwfr Llandrindod lon

Ond wfft i Sir Faesyfed,

un Seisnig remp yw hon! 

A fair proportion of Welsh academia long-ago washed its hands of Radnorshire.  Why they should be so eager to move an already precarious border 25 miles further west is a bit of a puzzle, but there you go.

The accepted viewpoint was that the Welsh language had died out in the county in the 18C and nothing seems to have been done to investigate the dialect of those few locally-born Welsh speakers shown by the 1911 census to have lived-on well into the 20C.  It's a pity, since Radnorshire must have been the transition zone between the Gwenhwyseg of the South East and the dialects of Montgomeryshire.

So we're left to search for scraps of information where ever we can find them, like in this letter to the Gloucester Journal in 1784.  For those too lazy to click the link, it describes the practice of making a small beer called merchin from kernel fruit - which I take to mean crab-apples or something similar. The use of lead-glazed jars in the production of this liquor lead to poisoning, hence the letter.

So what was merchin?  It certainly has the appearance of a Welsh word, although I can't find anything in the online version of Geiriadur Prifysgol Cymru.  Any ideas?