What was the first type of foam introduced into a hose stream?

The first type of foam introduced into a hose stream is chemical foam. This type of foam was developed in the early days of firefighting to combat flammable liquid fires, particularly those involving hydrocarbons. Chemical foam is created through a process involving the mixing of certain chemicals that produce a foam when aerated. This foam serves to smother the fire and prevent re-ignition by creating a barrier between the fuel and the fire.

Chemical foam is particularly effective because it can be used on various types of flammable liquids. Its ability to be easily produced and delivered through a hose stream made it a practical choice for early firefighting applications. As foam technology advanced, other types of foam like protein foam and alcohol foam were developed to address specific types of fires more effectively, but chemical foam remains notable as the first to be used in hose streams for fire suppression.