workaround for blocked applets on Safari 6 for Mac

As of Jan 30, 2013, Safari 6 on MacOS 10.7 with Java 1.7 installed will no longer run Java applets, including MarvinSketch.  The best solution is to revert to Safari 5.1.7, which will run applets even with Java 1.7 update 11. You can download Safari 5.1.x from http://mac.oldapps.com/safari.php.  Firefox 18.0 will also run applets, although they have to be activated manually on each page.  (An icon appears on the upper left that allows you to activate all applets on a single page.)  

Thank you for the information! We have came across this situation but haven't found a satisfying solution. Although your answer solvs the problem, but removes tons of updtates form the system. We just couldn't recommend this soultion to anyone. We hope Apple will come out with a better solution soon.

Apple released Java 1.7 update 13 sometime over the weekend.  After installing the update, Safari 6 will run Java applets, including MarvinSketch, again.

But I don't follow your response above.  How does using Safari 5.1.7 to run Java 1.7 remove any updates from the system?  

You said, we should downgrade from Safari 6 to 5.1.7. We might have some misunderstandindg, but thank you for your report.

Installing Safari 5.1 should have no effect on the system.  One can keep copies of both Safari 5.1 and 6.0, running the former only when Java is needed.  And Safari 5.1 runs Java 1.7, so there is no loss of Java functionality.

Apple has disabled Java 7 in Safari 6.0 again.  You can revert to Safari 5.1.7, as described above, or you can revert to Java 6 by following the instructions here.