Some pointers concerning the Bunsen burner:How is is possible to know if the gas tap is on or off?No matter what the shape or color of the tap, the same rule applies. When the tap is pointing in a different direction than the tube or pipe which carries the gas, then the gas cannot flow. In other words, it is off. The blue arrow below shows the direction of the gas flow. The yellow arrow shows the direction of the tap.
If the tap and the tube or pipe are both lined up and pointing in the same direction, then gas can flow through the tap. In other words, the tap is on.
Why are some Bunsen burners different?You may notice that certain models have an extra tap on them with a thin tube running up the side of the Bunsen burner. This is an extra feature which allows you to turn off the Bunsen burner without turning off the gas and turn it on again without having to relight it each time. Such Bunsen burners look like this:
Notice the small flame on the side which stays lit even when it is turned off. This is the secret for being able to turn the Bunsen burner on again without having to relight it. Notice also that the mini tap (with the black handle) follows the same rule as the yellow tap shown above. If you know that rule, you can easily tell if it is on or off. Don't burn yourself!
However, anything above the flame can get very hot: the wire grill, the top of the tripod, any glass beakers and solutions you heat up. Since hot glass and cold glass look the same and hot metal looks the same as cold metal, you should always presume that something is hot. Touch it lightly and quickly to find out its temperature or pick up things with metal tweezers to be sure not to get burned. - Good luck and stay safe! |
Off: 
On: 
The
only part of a Bunsen burner which gets hot is the top. The rest
of it is safe to touch. The collar, for example (shown in the
photo to the right) is safe to touch so that the flame can be
adjusted at any time, especially when the Bunsen burner is on.