rik,
You can find all your posts at My Place at top of the page. Then you can post on that thread so that there's continuity.
I moved the above post to this old one.
As for the paintings, the walkthrough states:
Click on both paintings until Holmes says they are identical.
Use the magnifying lens on both. See that the painting on the left has a picture of Lupin standing on the balcony holding a painting that is on fire (or on the shore at bottom left in far view).
Use the lamp on the left painting. See the letter I.
So - take the lamp from inventory and click it on the left painting
after Holmes says they are identical.
Then the left painting will be burned and you will see the letter I.