When I was at school, boys would have a small amount of burning charcoal in a jar.We heated the jar first, and didn't of course use a lid! We used them as hand warmers in winter. But quite often the bottom of the jar would crack and fall out. We used to carry these about on a loop of string. They did work for a time; even a lighted candle was good as a warmer. An empty bean can was best!
Oh, no! Not a thick jar; in fact the thinner the better. These were small jam (jelly) jars.I remember the Science teacher telling us that the bottom *thickest* part of the jar would crack because the outside of the glass was colder than the inside.
AS I said, we soon got used to the idea that an empty can was best. It held more burning coals, too!
Besides Brysings heater jar/can I was watching public television today and there was a show on crafts. the guy made a really cool lantern using a mason jar.
he made a kind of handle using some heavy gauge wire. then he put some colorful gravel/stones at the bottom and put a tea light candle on top of the gravel. then he lit it using one of those long lighters. it was very nice and charming
so yeah, it is possible to put fire in a jar without burning yourself or your house down.
Okay,Moonwind, and others. A simple science lesson. If you are making jam (jelly) and put the boiling jam into a cold jar, the jar will shatter.Because the inside of the jar is hotter than the outside,causing stress on the glass.But even your old grandma would know that if you heat the glass first it would not break!
It is the same with putting fire into a glass jar. If the inside is hot, and the outside cold, the jar will break; usually at the thickest part.But, heat the jar, and you can put a small fire in it.
However, if the outside of the jar cools quicker than the inside; the jar will no doubt break.
