I wrote
>>So Erastus set out to produce a lubricating oil that was not flammable.
>>He succeeded.
 
And Renee replied:
>I don't know if Claire was specifically speaking of petroleum
>jelly/Vaseline but just for the record, Vaseline IS flammable and
>it IS combustible.
 
I was indeed talking about petroleum jelly/Vaseline.  Technically it is
combustible but not flammable.  In layman's terms, it can be set on fire,
but it won't spontaneously burst into flame, which is what Erastus was
worrying about.
 
According to OSHA, the difference between flammable and combustible
depends on the volatility of the substance (it's tendency to evaporate
and make vapors) and the flash point of the vapor.  A 'flammable' liquid
is one that first, produces vapor, and secondly, has a flash point below
100 degrees fahrenheit.  (Combustible is above 100 degrees).
 
Vaseline is not considered flammable because it is not volatile; it
produces almost no vapor.  Furthermore, what little vapor there is has a
flash point of 400 degrees.  Technically it is a Class IIIb combustable
liquid, similar to olive oil.
 
This doesn't really bear on the safety to our little guys, except that
oils with high volatility (most petrochemicals) are dangerous because
damage is caused when the vapors are inhaled and get into the lungs.
Since vaseline doesn't produce those vapors, this isn't a problem when
vaseline is ingested as a laxative.
 
I hope this isn't getting too off-topic...
--Claire
[Posted in FML issue 4483]