On Sun, 12 Dec 2004 04:47:13 GMT, "Martin H. Eastburn"
wrote:

One reason for the non match is Propane is very often Not Propane.

Liquefied Petroleum gas or LPG - is a mixture of a number of gases
to make a general heat content of real Propane.

In warm states Butane is the word and they switch to LPG / Propane
in the winter as it won't liquefy like Butane will.

My bet is the mixture.

Now that you mention it, I have noticed the usability of my converted
gas range changing with the seasons. At my home here in California it
rarely gets too cold even for pure butane, but I guess my gas company
delivers on the other side of the mountain with the same trucks, so
they proably are changing mixtures.

Loren