No, I did no general search for `AgX´. Only at Apug. (Here is another AgX around; he saw some light though…)
Yeah AgX is a good name, but since it's so short it's hard to find a domain and can be expensive
To my information it was in the late twenties that by two other Agfa people (Mathies/Wendt) the predecessor of that stabilizer was found, a sulphur containing heterocycle.[...]But I admit finding these dates is difficult and the results are not necessarily trustworthy as long one did not see the original documents, which I did not.
1-phenyl-5-mercaptotetrazole is a famous sulfur containing heterocycle but I don't think it was from Wolfen. Another family of famous thiol, 2-mercaptobenzimidazole (2-MBI) and 2-MBI with substitution on the benzene ring are very commonly used, both in emulsion and developers, and this is from Wolfen. I thought TAI was late 20s but I was writing from memory, but it was actually the date of the previous generation compounds. I just searched for the date of TAI but date varies from 1935 or 1937. Birr has published a whole book but doesn't say the date of this work! Since this is not the only one he worked on but it just happened to be the famous compound, it may be hard to give a single date. Anyhow, it's mid 30s.
Glafkides say:
The most remarkable of all the photographic emulsion stabilizers are the
aza-indolizines discovered in 1935 by Birr.(32) They were kept secret for many
years, and enable gold sensitizers to be used which, as we know, produce
considerable storage fog.
Duffin (the author of an old emulsion technology book) says 1935.
The website of Organica (ORWO) says:
1936 The "Agfacolor-Neu" is presented to the
world. It is the first multi-layered colour film with
inserted couplers and it wins the Grand Prize of the
Paris World Exposition.
The Sodium salt of the Benzenesulfinic acid
(00540, S-Salt) is used in the manufacture of
emulsions as an antifogging agent since the middle
of the 30 ́s. Later on, other film manufacturers
will use the corresponding salt of the
4-Toluenesulfinic acid (12060).
Trough his search for stabilisers, which do not
have any negative influence on the sensitivity
while using Mercapto compounds, Birr comes
across Triazaindolizines, which Bülow had already
synthesised in 1907. The condensation product of
Ethylacetoacetate and 3-Amino-1,2,4-triazole will
soon be considered to be the perfect stabiliser (12210, TM-2, Sta-Salt). Within
two years it is used in all types of film and replaces the Mebi acid in the
"Agfacolor-Neu" material. Thus, it permits the full benefit of the Koslowsky
effect. This unique combination of Gold complex and Sta-Salt, which has been
kept secret until the BIOS- and FIAT- reports were published, has been applied
world-wide since 1945 in all Silver halide materials.
Until 1945, China-, Oxa-, Selena- and Thiacarbocyanines in form of their
Iodides, Bromides, Chlorates and Ethylsulfates are used as spectral
sensitisers in all black-and-white and colour materials (12680).
All this is getting very special and I guess annoying to some people and I sometimes think it would be better to have a special historic forum, but I do not see the smooth transition from issues coming up in other forums to that historic one.
I always think that forum is a better place for issues of current nature, that is, things that aren't fixed. Historical matters, among other things, are probably better served in the form of wiki or other forms where information is consolidated. Historical matters, of course, are more academic and meticulous checking with references and cross checking with multiple sources becomes more important, but doing this for every single thing in forums is tedious. I can make an AgX wiki site, or just join wikipedia, there are a couple of good options here.