I am looking for catalogue references for 4" blue pocket sputum flasks which have been in production at a considerable number of glass factories from ca. 1890 to the mid 1930s. They all have a lid - either screw cap, flip top or bayonet - in metal - and some have two lids, one on top and one on the bottom. The flasks are all cobalt blue and may or may not have embossed logos or measure division.
Not once (!) have I found these items detailed in product catalogues - and you will search bottle sites and books in vain, as if they never existed. True they are rare - but it is certain they were in production in France and in Germany, and quite likely also in Holland, Belgium and Denmark - and most probably in the UK as well.
But who?
Also, should you have one in your collection, let me know.