Don't know if you have a copy of Cyril Manley's book (Victorian Decorative Glass), but he does include some information on this subject on pages 45 and 99 - although too extensive to give here. Produced in several different colours, apparently, and the most important point is to make sure that the signed disc remains sealed and airtight. This is indeed a special kind of glassware, made in the U.K. for four years only - according to Manley it was first registered in 1849 and production ceased in 1852 - something to do with the complex method of production - also according to Manley there were health hazards for the makers. The coloured examples, especially when cut, are quite stunning - yellow apparently being the most rare.
There is a more extensive section in Hajdamach (British Glass 1800 - 1914) - page 269 - 272, where he details the late C20 experiment where there was a successful effort to make a goblet in clear glass - which during the making had to be re-heated twenty times!
Apparently a similar product was also made on the Continent and in the States.
Congratulations - very good find.
P.S. If you don't have these books - this is a good excuse to buy them - they are very useful.