INGEN-110USZ, JOHAN, a distinguished natural philosopher, was horn at Breda in 1730. Fur some years he practised medicine in that city, and employed his leisure in the performauce of experiments in chemistry and electricity ; but at length quitting his native country ho came to London, where his discoveries in those branches of science soon attracted the notice of the English philosophers, and led in 1769 to his being elected a Fellow of the Royal Society. He had the good fortune to obtain an introduction to Sir John Pringle ; and this cele brated physieiao, immediately appreciating his merits, warmly encou raged him In the prosecution of his researches, and honoured him with his esteem and friendship. Ho appears also occasionally to have corresponded with Franklin on the subject of electricity, which was at that time rapidly rising in importance.
The reputation of Ingen.housz as a physician must have been great, for the Empress Maria Theresa, who had lost two of her children by the small-pox, having directed her ambassador in London to consult Sir Johu Pringle respecting the choice of a physician whom she might invite to her court for the purpose of inoculating the young princes and princesses of the imperial family, Sir John, then president of the Royal Society, without hesitation recommended Dr. Ingen-housz ; the latter, accepting the invitation, set out, in 1772, for Vienna, where ho performed the operations with complete success. The example of the sovereign was followed by the nobility of Austria, and the children of the highest families of the country were inoculated by Ingen.houaz or under his immediate inspection. The empress, in testimony of her sense of his merit and attention, gave him the titles of Antic Councillor and Imperial Physician, and accompanied these honours with the grant of a pension, which he enjoyed during the rest of his life.
During his residence on the Continent, Ingeu-housz visited Italy, where he made experiments on the torpedo, France, and various parts of Germany; and at intervals continued to prosecute his researches in electricity and magnetism, and on the air produced by plants. While
at Vienna the Emperor Joseph IL honoured him with especial notice, inviting him frequently to the palace, and occasionally visiting him at his own house, in order to witness the performance of his philosophical experiments. After an absence of several years, Dr. Ingen-housz returned to England, where lie continued to prosecute his experi ments ; and an account of an electrophorus, which he had invented, is described in the ' Philosophical Transactions' for 1778. About tho same time he made the discovery that plants exposed to the light while growing discharge oxygen gas from their leaves into the atmos phere; and an account of his researches relating to this subject was in London in 1779, under the title of Experiments upon Vegetables, discovering the power of Purifying the Air in the Sun shine and of Injuring in the Shade,' Ate. The work was translated into French by the author, and published in Paris in 1780.
In the 'Philosophical Transactious ' for 1779 there Is an account of en electrical machine, which about that time Dr. Ingen-housz had constructed, and which probably led to the invention of the plate electrical machine, which is generally ascribed to Ingen-housz. Dr. Ingen-housz died on the 7th of September 1799.
Dr. Ingen-housz published in English a work entitled New Expe riments and Observations concerning Various Physical Subjects,' which was translated into Freuch and published iu Paris. lie also published in French a work entitled 'Esaai our la Nourriture des Plantes,' which was translated into English and published in Loudon in 1798.