Aren't they just
Armed with my glass dictionary I will have a go at a soda glass definition.....
Soda glass doesn't have any lead content so is much lighter and also more difficult to cut .
The alkali is soda rather than potash . Soda glass also lacks resonance but remains plastic longer than glass made with potash so it is much easier to manipulate as in the case of Venetian glassware (facon de venise). This candlestick being a classic example. Soda glass is slightly brownish , yellowish or greeny-grey . It also contains some lime and the basic proportions are 60% silica, 25% soda, & lime 15%...so it's often called soda-lime glass. The soda itself is used as a flux and reduces the fusion point of the silica i.e. the glass can be produced at a lower temperature. Kelp was used as a source of soda in England.
Gosh, anyone would think I knew what I was talking about
Well spotted , there is definitely a piece that looks something like Paul's , perhaps without the trailing.