Connect positive to positive first, there will be no spark.  Connect one
negative to the battery and the other to a part on the engine or frame.
The explosive gas detonating spark will be away from the explosive
gasses.  However, a battery with an internal short can spark internally
(due to low acid level) when jumped, or even when cranking, and ignite
the hydrogen gas inside.  This has happened to me!
--
Stuart MacMillan
Manager, Case Program
800-909-8244 ext. 8208

Getting your share of the Net yet?
http://cobaltgroup.com
http://UsedEquipNet.com