Chemical compounds can exist in three basic phases, gaseous, liquid, or solid. Gases consist of weakly bonded atoms and expand to fill any available space. Solids are characterized by strong atomic bonding and have a rigid shape. Most are crystalline, having a three-dimensional periodic atomic arrangement. Some, such as glass, lack this periodic arrangement and are noncrystalline, or amorphous. Liquids have characteristics that fall in between gases and solids. This cinemicrographic collection shows time-lapse movies of various chemical compounds as they change physical states.

• Aminocaproic Acid - Amicar is the common name for the compound aminocaproic acid (6-aminohexanoic acid), a coagulant that is used medically to reduce or prevent bleeding.

• Aspirin - Acetylsalicylic acid, better known as aspirin, is well known for its properties as a nonnarcotic analgesic and anti-inflammatory drug. A derivative of salicylic acid, the drug crystallizes in the form of a white, needle-like powder with only a faint odor.

• Calcium Chloride - A colorless or white solid, calcium chloride is well known for its anhydrous properties, absorbing more than its own weight of water. The compound is commonly used as a drying agent as well as for many other applications.

• Carnitine - Technically, this chemical is not an amino acid, but a water-soluble, vitamin-like compound that is readily synthesized in the body from the amino acids lysine and methionine and Vitamin C. It is important for helping the body's cells convert fatty acids into energy.

• Cholesterol - For animals, cholesterol is essential to life, a primary component of the membrane that surrounds every cell. It is also the precursor chemical from which the body synthesizes bile acids, steroid hormones, and vitamin D. Cholesterol circulates in the bloodstream and is manufactured by the liver and several other organs.

• DDT - One of the most effective, if deadly, pesticides, this organochlorine insecticide is certainly the most historically significant, due to its effects on the environment, agriculture, and human health.

• DNA - Deoxyribonucleic acid is a complex organic molecule found in all prokaryotic and eukaryotic cells and in many viruses. DNA carries the chemical information needed to direct protein synthesis and cell replication.

• Ephedrine - This drug belongs to the class of drugs that serve to open up the bronchial tubes of the lungs. It is derived from any of several species of evergreen shrubs belonging to the genus Ephedra and, in China, extracts from this plant have been used to treat colds and asthma for over 5,000 years.

• Glutamic Acid - First isolated in 1865, glutamic acid is an amino acid that functions as an important metabolic intermediate. A salt of glutamic acid, monosodium glutamate (MSG), is sometimes used as a condiment for flavoring foods.

• Liquid Crystals - Liquid crystals are sometimes referred to as the "fourth state" of matter following gases, liquids, and solids. The individual molecules flow past each other as they do in a liquid but tend to be oriented in the same manner, like the molecular arrangement in a solid crystal.

• Malonic Acid - Commercially, malonic acid is used to synthesize barbiturates, vitamins B1 and B6, and other compounds. Although malonic acid is a normal component of human urine, in small quantities, a genetic disorder called methyl malonic aciduria can cause high levels of methyl malonic acid in the blood serum and urine.

• Methylphenidate - More commonly known as Ritalin or Methylin, methylphenidate is a mild central nervous system stimulant prescribed primarily to treat attention deficit disorders and narcolepsy.

• Moth Balls - A crystalline white hydrocarbon, naphthalene is well known for the aromatic odor it gives to moth balls. Derived from coal tar, it is used to manufacture plastics, dyes, solvents, and other chemicals. It is also used as an antiseptic and insecticide.

• Nicotine - An oily liquid substance found in tobacco plants, nicotine is the principal alkaloid of tobacco. Nicotine is found throughout the tobacco plant, but occurs in highest concentrations in the leaves. In its pure form nicotine is colorless, but when exposed to light or air, it acquires a brown color and gives off a strong tobacco odor.

• Potassium Thiocyanate - This compound is one of the essential raw materials for the production of a variety of pharmaceutical products. When recrystallized from the melt, potassium thiocyanate will slowly crystallize, forming beautiful dendritic needle-like crystals.

• Sodium Thiosulphate - A white, crystalline, water-soluble salt of sodium, sodium thiosulphate is used primarily as a photographic fixing agent. It is also utilized for electroplating and tanning and widely used in the chemical, pharmaceutical, textile, and paper making industries.

• Strontium Acetate - Strontium acetate hemihydrate is a compound used in some toothpastes to desensitize teeth to extremes of hot and cold, sweets, acids, or contact. Tooth sensitivity, or "dentinal hypersensitivity" is one of the most common dental complaints of adults.

• Sulfanilamide - Sulfa drugs were the first chemical substances used to cure and prevent bacterial infections in humans. Sulfonamides are bacteriostatic drugs. They do not kill bacteria but inhibit growth and multiplication by interfering with their enzyme systems.

• TNT (Trinitrotoluene) - Trinitrotoluene is a nitrated toluene derivative that exists as a pale yellow, crystalline solid at room temperature. It can only be ignited with a detonator, making it a favored chemical explosive for munitions and demolitions.

• Urea - Also called carbamide, urea is a colorless, crystalline compound that is the chief nitrogenous end product of the metabolic breakdown of proteins in all mammals and some fishes.

• Vitamin C - Ascorbic acid is a water-soluble vitamin that functions as a powerful antioxidant. Although most animals can synthesize vitamin C, others -- such as humans, other primates, and guinea pigs -- obtain it only through their diets.

• Water - One of the most plentiful and essential of compounds, at room temperature, pure water is a colorless, tasteless, and odorless liquid.