Harm Reduction Sterilisation of injectables in the 19th & early 20th Century?

[Gaz_hmmmm]

I was wondering how back in the 19th Century and early 20th Century were injectable products such as morphine powder made sterile for injecting?

I’ve seen product labels for injectable tablets say “Use freshly boiled water to dissolve and inject.” but this was before IV became more popular medically in the 1950’s and obviously with intramuscular you have to be even more cautious.

What technique did they use to make stuff like the morphine sterile before you added it to boiled water?

Does anyone know?