Lycopodium powder

Lycopodium powder is a yellow-tan dust-like powder historically used as a flash powder. It is composed of the dry spores of clubmoss plants, various fern relatives principally in the genera Lycopodium and Diphasiastrum. When mixed with air, the spores are highly flammable because of their high fat content and their large surface area per unit of volume — a single spore's diameter is about 33 micrometers (μm),^[1] requiring about 30 laid side by side to span a millimeter, or 750 to span an inch. Preferred source species are Lycopodium clavatum (wolf's-foot clubmoss) and Diphasiastrum digitatum (common groundcedar) because these widespread and often locally abundant species are both prolific in their spore production and easy to collect.^{[citation needed]}

Lycopodium has been used in fireworks and explosives ^{[citation needed]}, fingerprint powders, as a covering for pills, and as an ice cream stabilizer. Today, the principal use of the powder is to create flashes or flames that are large and impressive but relatively easy to manage safely in magic acts and for cinema and theatrical special effects. Lycopodium powder is also sometimes used as a lubricating dust on skin-contacting latex (natural rubber) goods, such as condoms and medical gloves.^[2]

In physics experiments and demonstrations, lycopodium powder is used to make sound waves in air visible for observation and measurement, and to make a pattern of electrostatic charge visible. The powder is also highly hydrophobic; if the surface of a cup of water is coated with lycopodium powder, a finger or other object inserted straight into the cup will come out dusted with the powder but remain perfectly dry.

As a then-common laboratory supply, lycopodium powder was often used by inventors developing experimental prototypes. For example, Nicéphore Niépce used lycopodium powder in the fuel for the first internal combustion engine, the Pyréolophore, about 1807,^[3] and Chester Carlson used lycopodium powder in 1938 in his early experiments to demonstrate xerography.^[4]

References