Bloodletting was a regular form of medical treatment for ancient Greeks, with its benefits debated by scholars such as Hippocrates and Galen. Bloodletting in Central America. Bloodletting or autosacrifice was a cultural trait of most of the societies in Mesoamerica, beginning with the Olmec perhaps as early as 1200 AD. 1  This type of religious sacrifice involved a person using a sharp instrument such as an agave spine or shark's tooth to pierce a fleshy part of his own body.
A mixture formed when one substance dissolves in another is called a solution. One example is salt water. In a solution, the component substances cannot be distin-guished from each other and they remain evenly distrib-uted throughout; that is, the mixture is homogeneous (ho-mo-JE-ne-us). The dissolving substance, which in the body is water, is the solvent. The substance dis- solved, salt in the case of salt water, is the solute . An aqueous (A-kwe-us) solution is one in which water is the solvent. Aqueous solutions of glucose, salts, or both of these together are used for intravenous fluid treat- ments.
Whether a substance dissolves or not depends on the relative forces between the solvent particles and the solute particles as well as their temperature. Dissolving gases are also highly influenced by the pressure the gas is under when encountering the solvent. A substance only dissolves if the attraction between the particles of the solute and the solvent is enough to overcome the attraction of the particles of each substance for others of the same type. For instance, the attraction between the ions in table salt and water molecules is enough to both pull individual ions away from the salt crystal and to separate the water molecules to accommodate the ions. Benzene, on the other hand, does not attract the ions of salt strongly enough to remove them from the crystals. Napthalene does not dissolve in water because napthalene does not exert a strong enough attraction to water molecules to separate them and make room for itself.