It remains common practice to name individuals on patents and addresses can be either a person. But this type of data fully searchable is the raison d'etre of the Glass Study and over the next few years we can quickly find more on this company.
Jonas Lang & Co, 124 are listed under 'Agents, Commissioneers and Representatives' in Rousset 1909. If they also appear in the trades section will have to wait until it is fully digitised.
A J. Lang (Austria-Hungary) also received a bronze medal at Paris 1878, but no further details in the following report on a quick glance.
Jules Lang & Sons were established in 1858 but that does not mean that they had not gone under a different name before that 1950 reference when they were located at 96 Hatton Garden, London. 1950 also gives us Warehouses: Stoke-on-Trent and London, Manchester Offices and Showrooms.
In 1949 we find "Jules Lang and Son on Nov. 9, 1899, as a bookkeeper, later becoming manageress when the firm moved to Charlton Place Islington, N.1, during the First World War." Individuals mentioned are Fernand Lang and Bernard Lang. So Fernand fits the bill for F R Lang.