Thanks Adam, that's very useful.
It does seem odd to me that there are more heads specified than glass bodies for the menstrue? A mistake? There's simply no way you would break the heads that often compared to the bodies, unless you were employing children and left the bodies in place whilst taking the heads on and off repeatedly to fill them back up.
Which come to think of it isn't so impossible. Of course mine, and everyone elses experience these days is not with actual potash or soda/ lime glass, so we probably have a slightly different sense of what treatment glass will survive than was the case in the 16th century.
It would also be interesting if there was more mention of the size of the cucurbits and heads for them.
I'll have to buy a copy of your edition, or go and read the electronic ones, but I have trouble thinking of anything that would burn onto glass that is also volatile enough to leave the glass cucurbit it the first place.