patents

Searching old patents related to alt-photo techniques I have found some
interesting ones.
For example, by means of the British Esp@cenet site
(http://gb.espacenet.com/) I have found the beautiful Manly's ones:
GB189810026 (ozobrome, 1898) and GB190517007 (carbro, 1905).
Though the US patens database (http://www.uspto.gov/patft/index.html) does
not allow the complex search on patens before 1976, I have been able to find
a 1933 patent on the preparation of ferric oxalate by oxidation of ferrous
oxalate with hydrogen peroxide (Leo P. Curtin, US1899674 and CA334904).
Esp@cenet gives also a 1985 patent for the preparation of iron(III) ammonium
oxalate (PL245415) without any text, and I am not able to find it using the
Polish database.

Finally, I wish to bring your attention to a very recent "A method for
making internegative" (JP2004058378). See
http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=JP2004058378&F=0 (all in one
line).
It is entirely written in Japanese, but look at the images in the last two
pages!!!

Alberto
Received on Tue Feb 14 04:23:37 2006