Landslides Along the Columbia River Valley, Northeastern Washington
July 2, 2009
Things have been a bit busy this week with family coming into town and a shift in projects at my work. However, I will be back on track next week and start adding in more landslide information.
Recently, Lee, the librarian here at the Washington Geological Survey, gave me an extra copy of the Geological Survey Professional Paper 367 (Landslides Along the Columbia River Valley, Northeastern Washington). I will be adding in these landslides to our landslide database and probably pluck a few out here and there to add into this blog.
Hope everyone has a safe 4th of July. While watching aerial bursts and swinging around sparklers, remember to think about the chemical and geological sciences that went into creating such magical fires.
Colors in fireworks are usually generated by pyrotechnic stars—usually just called stars—which produce intense light when ignited. Stars contain five basic types of ingredients.
* A fuel which allows the star to burn
* An oxidizer—a compound which produces (usually) oxygen to support the combustion of the fuel
* Color-producing chemicals
* A binder which holds the pellet together.
* A Chlorine Donor which provides chlorine to strengthen the color of the flame. Sometimes the oxidizer can serve this purpose.
Some of the more common color-producing compounds are tabulated here. The color of a compound in a firework will be the same as its color in a flame test (shown at right). Not all compounds that produce a colored flame are appropriate for coloring fireworks, however. Ideal colorants will produce a pure, intense color when present in moderate concentration.
Color Metal Example compounds
Red Strontium (intense red): SrCO3 (strontium carbonate)
Lithium (medium red): Li2CO3 (lithium carbonate)
Orange Calcium: CaCl2 (calcium chloride)
Yellow Sodium: NaNO3 (sodium nitrate)
Green Barium: BaCl2 (barium chloride)
Blue Copper halides:CuCl2 (copper chloride), at low temperature
Purple Potassium or Strontium + Copper: KNO3 (potassium nitrate) or SrCl+ + CuCl+ (Strontium chloride + Copper chloride)
Gold Charcoal, iron, or lampblack
White Titanium, aluminium, or magnesium powders
The brightest stars, often called Mag Stars, are fueled by aluminium. Magnesium is rarely used in the fireworks industry due to its lack of ability to form a protective oxide layer. Often an alloy of both metals called magnalium is used.
Many of the chemicals used in the manufacture of fireworks are non-toxic, while many more have some degree of toxicity, can cause skin sensitivity, or exist in dust form and are thereby inhalation hazards. Still others are poisons if directly ingested or inhaled.