Reduction of Phosphate Esters

My Organic Chemistry professor told an interesting story during class the other day. I don't remember what his point was, but in it he mentioned how he was once given the task of reducing a phosphate triester to a trialkyl phosphate using Zinc dust:

O=PR3 --(Zn)--> PR3

The story goes that he was having no luck, but it was a proven procedure from 1887. So finally he asks his instructor what he's doing wrong...

The instructor looks at his equipment and reagents, then dumps the Zinc powder on the floor and shuffles all over it. "Sweep it up and try again," he says. The reaction worked beautifully with the addition of the "catalytic crud," as he called it.

In 1887, they did not have pure reagents--it was mostly stuff they'd made themselves. So whatever was on the floor helped my professor's zinc powder out

But that aside, this is a very interesting reaction. Trialkyl Phosphates are fairly unreactive in the ways I'd like ;-), boring, and aren't so hard to get [although they are possible carcinogens]:

Ag3PO4 + RI --> R3PO4 + AgI

But conversion to a Phosphite gives a direct precursor to toxic organophosphates. From there, an Alkyl Halide could be reacted with it to form a Phosphoryl bond, according to the Arbusov Reaction.

So of course I want to know the details of how his Zinc reduction worked, but I dared not ask. When he drew the structure "O=PR3" on the board, I assume the R's weren't meant to represent Phosphorus-Carbon bonds, but P-O-C bonds.

After class, I promptly went to the chemistry library to find whatever information I could on this reaction, but could find nothing...

So, what do you all think? Any ideas on how to approach this?

Unfortunately, it is just that kind of small class--the special organic chem class for chemistry majors, so of course our professor wants to know us. That's not so bad, only we are on odd terms which I don't feel like getting into I might just ask though.