The name "soda ash" is based on the principal historical method of obtaining alkali, which was by using water to extract it from the ashes of certain plants. Wood fires yielded potash and its predominant ingredient potassium carbonate (K2CO3), whereas the ashes from these special plants yielded "soda ash" and its predominant ingredient sodium carbonate (Na2CO3). The word "soda" (from the Middle Latin) originally referred to certain plants that grow in salt solubles; it was discovered that the ashes of these plants yielded the useful alkali soda ash. The cultivation of such plants reached a particularly high state of development in the 18th century in Spain, where the plants are named "barrilla"; the English word is "barilla". The ashes of kelp also yield soda ash, and were the basis of an enormous 18th century industry in Scotland. Alkali was also mined from dry lakebeds in Egypt.