A perfect storm – brutal cold, an Eagles home game Sunday afternoon, and a Mummers Parade on Monday – has made hand warmers a tough find in and around Philly.

My colleague Mari Schaefer, assigned to cover the Mummers Parade, went to four stores in the city, Devon and Wayne in search of  hand warmers Friday and Saturday, only to find them sold out. Her search was to continue Sunday.

I figured that if there are recipes for making your own slime, there must be a how-to for hand warmers. Indeed, there is. Online offers a few recipes, of course.

But this is a city rich with academic minds. So I consulted one – Robert J. Levis, a chemistry professor at Temple University, who turned his Rose Valley living room into a mini-lab Sunday morning to test out a couple DIY methods for making hand warmers.

Here's the one he suggests. He ensures you don't need a Ph.D. in chemistry to do it:

In a sealable plastic bag, put equal parts ice-melt salt (table salt will not do) and water. "And, boom, you have warm water," Levis said. "You should get a half an hour or hour of warm water out of that."

Why does it work?

"When you have a salt like calcium chloride, which is in the ice melt, when that dissolves in water, it gives off energy," Levis said.

Why it gives off energy has to do with two words: hydrogen bonding. Which is why table salt won't prove as effective. It doesn't form as many hydrogen bonds as calcium chloride.

Now, obviously, because of the fast-acting nature of this concoction, there will be no mixing it at home and taking it to the parade. This will be an on-site job. If you don't want to deal with water in a bag and the possibility of the bag breaking, Levis advises adding equal parts of dehydrated polymers   from a clean diaper (they resemble crystals), which will soak up the water and work just as effectively when mixed with the calcium chloride.

"Mix it at the parade and try not to make a mess," Levis said. "But don't stay home. Go down to the Mummers."

And don't worry about our parade reporter, Schaefer. She finally found some hand warmers Sunday afternoon at Dick's Sporting Goods in King of Prussia where, Schaefer reports: "They didn't have a lot left."