Elden,

As I mentioned earlier, I'm not going to get a chance
to do any in-depth research on your question about the
various companies that made or used anhydrous ammonia
until sometime this weekend. However, as I ran out the
door to work this morning, I grabbed a Dow Chemical Co.
publication that I acquired some time ago. It's called
"Tank Car Facts", and was intended for use by the Dow
Tank Car Department (Yes, they actually had one). The
publication is dated June 5, 1950.

In the entire book they only mention Anhydrous Ammonia
once, in reference to the ICC-106A500 class of tank car:

"SPECIFICATIONS FOR ICC 106A500

This specification covers welded steel tanks to be
mounted on or to form part of a car. This class of
tank car is called, the Multi-Unit or Cradle car,
and is used for the transportation of 15 one-ton
cylinders.

Tanks or cylinders built under this specification
must be cylindrical with heads dished convex inward.
All openings must be located in the heads. Tanks must
be securely attached to a car structure in such a
manner that they may be removed for filling by the
consignor and emptying by the consignee. Each tank
must be tested to 500 pounds per square inch.

There are many products which this type of car may
carry. It was originally designed for Chlorine and
Anhydrous Ammonia, however, the bulk of our Chlorine
and Anhydrous Ammonia, today, is carried in tank cars.
This car is very serviceable for customers which require
cylinder use, and is used by our Great Western Division
to very good advantage."

So there you have it. That Dow mentions Anhydrous Ammonia hints
that they did carry it, but whether they produced it themselves
or bought it elsewhere still needs to be researched. More details
as they become available...

As an aside, I believe somebody made this car in H.O. brass once
upon a time. Whether it fits your period of modeling I can't say.
I'm not even sure how far past the early 1950's this car was used
on American railroads.

Shawn Beckert

Jeff Coleman