Blagden , Sir , Charles , 1748-1820 , Knight , physician

Blagden was born at Wotton-Under-Edge, Gloucestershire. He studied medicine at Edinburgh and received his M.D. in 1768. He was elected FRS in 1772 and served as a medical officer in the British Army from about 1776 to 1780. He was Henry Cavendish's assistant from 1782 to 1789, from whom he received an annuity and a considerable legacy. Blagden succeeded Paul Henry Maty as Secretary of the Royal Society in 1784 (while the Society was divided over the efficacy of its President, Sir Joseph Banks, a close friend of Blagden's), serving until 1797. Both in this capacity and as Cavendish's assistant he became involved in the prolonged 'water controversy' - who had priority in discovering the composition of water, claimed by both Cavendish and James Watt in England and A L Lavoisier in France. Blagden admitted responsibility for conveying, quite well-meaningly, word of the experiments and conclusions of both Cavendish and Watt to Lavoisier; and he overlooked errors of date in the printing of Cavendish's and Watt's papers. His experiments on the effects of dissolved substances on the freezing point of water led to what became known as 'Blagden's Law', where he concluded that salt lowers the freezing point of water in the simple inverse ratio of the proportion the water bears to it in the solution. In fact Richard Watson had first discovered the relationship in 1771. Blagden spent much of his time in Europe, particularly in France, where he had many friends among French scientists such as C L Berthollet. He died in Arcueil in 1820. He was knighted in 1792.