Lycopodium powder is a yellow-tan dust-like powder, consisting of the dry

spore In biology, a spore is a unit of sexual reproduction, sexual (in fungi) or asexual reproduction that may be adapted for biological dispersal, dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores fo ...

s of clubmoss plants, or various fern relatives. When it is mixed with air, the spores are highly flammable and are used to create

dust explosion A dust explosion is the rapid combustion of fine particles suspended in the air within an enclosed location. Dust explosions can occur where any dispersed powdered combustible material is present in high-enough concentrations in the atmosphere ...

s as theatrical special effects. The powder was traditionally used in physics experiments to demonstrate phenomena such as

Brownian motion Brownian motion is the random motion of particles suspended in a medium (a liquid or a gas). The traditional mathematical formulation of Brownian motion is that of the Wiener process, which is often called Brownian motion, even in mathematical ...

Composition

The powder consists of the dry

s of clubmoss plants, or various fern relatives principally in the genera '' Lycopodium'' and '' Diphasiastrum''. The preferred source species are ''Lycopodium clavatum'' (stag's horn 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.

Main uses

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 Theatre or theater is a collaborative form of performing art that uses live performers, usually actors to present experiences of a real or imagined event before a live audience in a specific place, often a stage. The performers may communic ...

special effects. Historically it was also used as a photographic flash powder. Both these uses rely on the same principle as a

, as the spores have a large surface area per unit of volume (a single spore's diameter is about 33 micrometers (μm)), and a high

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...

content. It is also used in

fireworks Fireworks are Explosive, low explosive Pyrotechnics, pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays (also called a fireworks show or pyrotechnics), combining a large numbe ...

and

explosive An explosive (or explosive material) is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An ex ...

s, fingerprint powders, as a covering for

pill Pill or The Pill may refer to: Drugs * Pill (pharmacy), referring to anything small for a specific dose of medicine * "The Pill", a general nickname for the combined oral contraceptive pill Film and television * ''The Pill'' (film), a 2011 fil ...

s, and as an

ice cream Ice cream is a frozen dessert typically made from milk or cream that has been flavoured with a sweetener, either sugar or an alternative, and a spice, such as Chocolate, cocoa or vanilla, or with fruit, such as strawberries or peaches. Food ...

stabilizer.

Other uses

Lycopodium powder is also sometimes used as a lubricating dust on skin-contacting latex (natural rubber) goods, such as

condom A condom is a sheath-shaped Barrier contraception, barrier device used during sexual intercourse to reduce the probability of pregnancy or a Sexually transmitted disease, sexually transmitted infection (STI). There are both external condo ...

s and medical gloves. In

physics Physics is the scientific study of matter, its Elementary particle, fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge whi ...

experiments and demonstrations, lycopodium powder can be used to make

sound wave In physics, sound is a vibration that propagates as an acoustic wave through a transmission medium such as a gas, liquid or solid. In human physiology and psychology, sound is the ''reception'' of such waves and their ''perception'' by the ...

s in air visible for observation and measurement, and to make a pattern of electrostatic charge visible. The powder is also highly

hydrophobic In chemistry, hydrophobicity is the chemical property of a molecule (called a hydrophobe) that is seemingly repelled from a mass of water. In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, thu ...

; 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 completely dry. Because of the very small size of its particles, lycopodium powder can be used to demonstrate

. A microscope slide, with or without a well, is prepared with a droplet of water, and a fine dusting of lycopodium powder is applied. Then, a cover-glass can be placed over the water and spore sample in order to reduce convection in the water by evaporation. Under several hundred diameters magnification, one will see in the microscope, when well focused upon individual lycopodium particles, that the spore particles "dance" randomly. This is in response to asymmetric collisional forces applied to the macroscopic (but still quite small) powder particle by microscopic water molecules in random thermal motion. As a then-common laboratory supply, lycopodium powder was often used by inventors developing experimental prototypes. For example,

Nicéphore Niépce Joseph Nicéphore Niépce (; 7 March 1765 – 5 July 1833) was a French inventor and one of the earliest History of photography, pioneers of photography. Niépce developed heliography, a technique he used to create the world's oldest surviving ...

used lycopodium powder in the fuel for one of the first internal combustion engines, the Pyréolophore, in about 1807, and

Chester Carlson Chester Floyd Carlson (February 8, 1906 – September 19, 1968) was an American physicist, inventor, and patent attorney born in Seattle, Washington. Carlson invented electrophotography (now xerography, meaning "dry writing"), producing a dry ...

used lycopodium powder in 1938 in his early experiments to demonstrate

xerography Xerography is a dry photocopying technique. Originally called electrophotography, it was renamed xerography—from the Greek roots , meaning "dry" and , meaning "writing"—to emphasize that unlike reproduction techniques then in use such as c ...

References

{{reflist Pyrotechnic compositions Powders