Sulfur sticks are used in industrial ammonia

Ammonia

Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...

 refrigeration

Refrigeration

Refrigeration is a process in which work is done to move heat from one location to another. This work is traditionally done by mechanical work, but can also be done by magnetism, laser or other means...

 systems to detect minor ammonia leaks. A sulfur stick is made from a wick which contains particles of sulfur.

The sulfur stick is lit and smolders, something like the taper that is used to light fireworks. The color of the sulfur smoke is used to find the leak. When there is no ammonia the smoke is colorless but when ammonia is present the combined sulfur and ammonia vapors produce a white smoke.

Sulfur sticks have been used to find ammonia leaks for at least 100 years.