Instructions for magnesium photography, around 1915 (in Spanish).
“AT NIGHT, with utmost ease and with no preparation you can take beautiful pictures with magnesium. Just press the release and touch with a match a magnesium capsule that costs $ 0.20.
It is the most practical method for children photography.
Do a test and you will be convinced that this procedure is even simpler than daylight photography.
ASK FOR INFORMATION.”