Excerpt from Crucible, January 2005.

Learning by Accident
««« Submitted by a STAO member.

Learning by Accident is an ongoing Crucible feature, in which real-life lab accidents or incidents are recounted and explained. The goal is to highlight the consequence of ignoring safety rules so that science educators will be further encouraged to become knowledgeable, and to take appropriate action, in areas of safety that affect their daily activities in the science classroom. Submissions are encouraged. Anonymity will be guaranteed. Please send written descriptions to Ian Mackellar, STAO Safety Committee Past-Chair, Box 191, MAITLAND, ON K0E 1P0

Supercharged

Imagine my surprise recently when I was pontificating about careers in chemistry, only to be interrupted by a student putting her hand into her pocket and exclaiming, “Ow, hot!” I asked her what she had in there and she told me that she had a couple of batteries. I told her to take them out of her pocket, to which she replied that they were too hot. I was confused because I thought she was burning from the battery acid coming into contact with her skin. In fact, when I retrieved a pair of crucible tongs for her to take out the hot batteries, she emptied the contents of her pocket and found that she had two dry cells (one hot, one cold) and a variety of coins. I realized that she had managed to create a short circuit with one of the batteries and the coins! In the end she came out of the incident with only a minor red patch on her skin. I found it ironic that I was having a “Learning by Accident” moment even though I was not doing a lab or demonstration!

Comments from the Safety Committee
This incident shows that improperly handled or stored dry cells can cause injury if they are allowed to short circuit. The major danger is from heat and possibly fire that can cause

personal injury, rather than electro¬cution. The student incurred only a minor skin irritation in this event, but could have suffered injuries as severe as second degree burns.
Dry cells should be handled in such a way that the terminals cannot touch and create a short circuit.

More detailed advice with respect to the storage and safe use of dry cell batteries can be found in the STAO publication(s) Be Safe! and/or Stay Safe! available for purchase from the STAO Science Store.