Scottish Inventions and Discoveries
- Carbon Dioxide - Joseph Black (1728-1799)
Joseph Black was born in Bordeaux, France, where his father (born in Belfast, Northern Ireland) and mother (born in Aberdeen, Scotland) were involved in the wine trade. Black had 12 brothers and sisters. He studied at the University of Glasgow and attended Edinburgh University to study medicine.
While he was there he studied what we now know as carbon dioxide (CO2). In the 17th century it had been observed that when charcoal is burned in an enclosed vessel, the mass of the resulting ash was less than the original charcoal. The interpretation at the time was that this was due an invisible substance (called phlogiston or "wild spirit") that was liberated when burning. In the 1750s, Joseph Black who found limestone heated or treated with acids yielded a gas which was denser than air. The gas did not support life or flames. He also demonstrated that the gas was produced by animal respiration.
Around the same time, Black developed an analytical balance based on a light-weight beam balanced on a wedge-shaped fulcrum. Each arm carried a pan on which the sample or standard weights was placed. This was more accurate than any other balance of the time and became an important scientific instrument in most chemistry laboratories.
In 1761, he discovered that when ice melts it absorbs heat without changing temperature. From this he concluded that the heat must have combined with the ice particles and become latent. This discovery was perhaps his most important, and the one on which his scientific fame chiefly rests. He also showed that different substances have different specific heats.
Black was a friend of James Watt and was associated with David Hume, Adam Smith and others in what is known as the Age of Scottish Enlightenment. He died in Edinburgh at the age of 71 and was buried in Greyfriars Churchyard.
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