To the top of finial jar measures approx 12", base diameter is 5". Embossing reads, Ajax Fire Engine Works, PUT LEAD STOPPER IN BOTTLE BEFORE PUTTING BOTTLE INTO ENGINE, New York city, USA. 

The engine was a large tank on wheels which was filled with water containing dissolved baking soda. The jar in this listing was filled with sulfuric acid and the glass stopper was replaced with one made of Lead. Jar was then placed in the tank. When it was time to use the chemical engine firefighters would tilt tank top down allowing Lead stopper to fall away releasing sulfuric acid into the baking soda water mix. The resulting reaction produced carbonic acid gas as well as a rapid increase in pressure within the tank. The pressure resulted in a 80 ft stream of the chemical aimed at the fire and the carbonic acid gas would smother the fire.