It embodies all the essential components of present day definition, i.e. site, nature, aggravating and relieving factors and referral. According to him angina is chest pain which is precordial, temporary, exertional, emotional, burning like and relieved by rest. He also linked this kind of pain to obesity (medoroga).
Pure substances are defined as substances that are made of only one type of atom or molecule. The purity of a substance is the measure of the extent to which a given substance is pure. The physical properties of a pure substance include well-defined melting and boiling points. The purity of a substance also impacts the chemical properties of a substance by reducing the chances of unexpected products being formed if impurities are present within the substance.
Chemical substances are often called 'pure' to set them apart from mixtures. A common example of a chemical substance is pure water; it has the same properties and the same ratio of hydrogen to oxygen whether it is isolated from a river or made in a laboratory. chemical substance is a form of matter that has constant chemical composition and characteristic properties. It cannot be separated into components by physical separation methods, i.e., without breaking chemical bonds. Chemical substances can be chemical elements, chemical compounds, ions or alloys.