Spark plug

General Discussion
1

1)what is hot tube ignition?

2)soot proof plugs?

2

These were used by some manufacturers in very early engine design (like the late 1800s).
Google is your friend.

3

Hmm, interesting questions, but why do you ask. Personally I never heard of either thing. Kinda makes ya wonder.

4

http://www.old-engine.com/maghtu.htm

http://oz.plymouth.edu/~trentb/ModelT/T7299/T7299.html

My wild guess with the “soot proof plugs” is that they probably had a higher operating temperature than previous plugs.

5

Well, that’s a bizarre coincidence! I’ve been reading a Clymer book compiling lots of old car info and ads from about 1895 to 1920, and one was from 1903 or so, for spark plugs claimed to be ‘nearly soot proof’!