Asphyxiant gas can smell the odorants, and assigning a different smell to each gas may be impractical. Another difficulty is that most odorants (e.g., the thiols) are chemically reactive. This is not a problem with natural gas intended to be burned as fuel, which is routinely odorized, but a major use of asphyxiants such as nitrogen, helium, argon and krypton is to protect reactive materials from the atmosphere. The dangers of excess concentrations of nontoxic gases has been recognized for centuries within the mining industry. The concept of black damp (or "stythe") reflects an understanding that certain gaseous mixtures could lead to
Most common words in Spanish of spoken Spanish. Most common words in Spanish Below are two estimates of the most common words in Modern Spanish. Each estimate comes from an analysis of a different text corpus. A "text corpus" is a large collection of samples of written and/or spoken language, that has been carefully prepared for linguistic analysis. To determine which words are the most common, researchers create a database of all the words found in the corpus, and categorise them based on the context in which they are used. The first table lists the 100 most common word forms from the Corpus de Referencia