Later, they contained *carbon tetrachloride* which when heated produces Phosgene and Hydrogen Chloride gas, which are fire-inhibitors, but also deadly to humans trapped in the fumes!
They could be hand-held missiles, kept in a convenient carrying case...
(📷: 1stdibs.com)
But other innovations included spring-loaded racks that lobbed them if heat caused a lead alloy securing them to melt.
Or giant racks of them suspended upside down with wax stoppers. Heat melted them open, where diverters spread the fire inhibitor.
Dry-cleaning fluid?
I never would have guessed that carbon tet was once used as a fire suppressant.
Clearly it wasn't as good an idea as it seemed at the time -- a good lesson for today, perhaps?
Carbon tet???? Ugh.
When I lived in SF my neighbor was moving back to Hong Kong and gave me her cleaning supplies. Included was a liter bottle of benzene.