Great finds Vic. The introduction of the 1851 is treatise is opinionated. You get to sense a little of the Gothic Revival attitudes. In the 1857 one it warns, while descibing Gold-based enamels, that German gold coins are alloyed with silver. Fun stuff.
Given this was decades before the greatest American invention ever (the glass wheel), I was curious to see how they cut glass. They suggest a diamond (which I found OK for a straight line but not much use otherwise), a hot poker (which, when I tried it, just cracked the glass roughly where I wanted it) or cutting with scissors under water, which is basically safe grozing but it wrecks the scissors. Quite amazing the stuff they cut with those limitations.
Holy smokes. The 1851 one is an undergrad course in silicate chemistry. I've never seen that comprehensive information in the enameling and overglaze painting books I've gone through (quite a few). Now I wish I had the tenacity to comprehend it.