Re: oil (fwd)

---------- Forwarded message ----------
Date: Sun, 12 Jul 1998 17:49:43 -0700
From: Jim Lux <jimlux-at-earthlink-dot-net>
To: Tesla List <tesla-at-pupman-dot-com>
Subject: Re: oil (fwd)

> ---------- Forwarded message ----------
> Date: Sat, 11 Jul 1998 09:25:18 -0400
> From: Kevin Wahila <kevinw-at-stny.lrun-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: oil
> i finally bought some pure mineral oil, but i was just wondering what the
> story is with different types of cooking oil?  do they work and if not,
> come?
Here it is, more about oils than you really wanted to know, but I got
started and just kept rolling.

They're not even remotely the same.... mineral oil is a very highly refined
component of crude oil (i.e. that which comes from rocks and minerals).  It
is basically a long hydrocarbon chain (generically a paraffin or alkane)
and is tasteless, fairly odorless, colorless, etc. and, by and large,
inert. (propane, gasoline, kerosine, etc are shorter chains and has a lower
boiling point, the wax that you put on top of canned foods (called paraffin
here in the US) is a longer chain, and is solid at room temperature.)

Cooking oil is derived from fats from animals (lard, tallow, butter, ghee,
whale oil, etc.) or plant seeds (palm, coconut, olive, safflower, corn,
rape, flax, etc., etc.). As such, it tends to have a distinct flavor or
odor,usually considered beneficial, as well as some useful heat transfer
and viscosity properties, and an ability to bind to starch molecules (how
else would you make that beurre blanc without butter and flour), etc.  Most
important, it also has components in it which easily oxidize and spoil.
Even if it doesn't spoil, it tends to get gummy. (although mineral oils can
also oxidize, as well, it is just slower. They also add an anti-oxidant to
most commercial mineral oil: Vitamin E or BHT, normally)

A big problem with cooking oil as an insulator is the water content. Most
oils will pick up at least a little water from the air. Water in cooking
oil isn't really a problem until the percentage gets up around 25% (of
course, if you've tried cooking with one of those "Lite" spreads which use
well emulsified water to reduce the fat content (per gram of product),
you'll know what water in the oil does).  However, even a few ppm of water
in oil ruins it as an insulator, much less a significant fraction of a
percent. (it will raise the dielectric constant though!)

An interesting exception to the general electrical non-usefulness of plant
oils is castor oil, made from the seeds of the castor bean plant, which has
good lubrication and non-spoiling properties, as well as a high dielectric
constant (and we all know we want that). Maxwell Labs uses castor oil in
their caps. If you decide to press your own castor oil (we have lots of
castor bean bushes growing around here), you should know that castor beans
contain ricin, famous as one of those "undetectable exotic tropical
poisons" (perhaps in Holmes' day, but not with modern Gas Chromatography
(and, of course, compared to England, Southern California is tropical)).

Another useful plant oil is that from jojoba beans, which has properties
much like whale oil, but doesn't require the work of chasing and catching
whales to get it. Apparently, it has good properties as a lubricant and in
cosmetics, and is also non-spoiling and inert.