There are better, and safer, ways to teach heat transfer. I cannot, in good conscience, recommend putting your hand into a fire or into liquid nitrogen for "demonstration" purposes. Doing so invites the potential for injury and I have seen impressionable
youth try to imitate such actions without the proper understanding of the principles involved.
I believe the ACS has also formally discouraged this type of activity in chemistry outreach programs.
Sent from my Verizon, Samsung Galaxy smartphone
-------- Original message --------
From: davivid <davivid**At_Symbol_Here**WELL.COM>
Date: 9/22/16 7:43 PM (GMT-07:00)
Subject: Re: [DCHAS-L] Liquid Nitrogen Ice Cream