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Andrews his father’s office, which he left in 1828 for the university of Glasgow, where he studied chemistry under [q. v.]

In 1830 he travelled to Paris, where he became acquainted with many of the leading French chemists, and spent a short time in the laboratory of Dumas. The following years were occupied in medical studies, first at Trinity College, Dublin, then at Belfast, and finally in Edinburgh, where in 1835 he received the diploma of the Royal College of Surgeons of Edinburgh, and graduated M.D. Declining the chairs of chemistry in the Richmond and Park Street schools of medicine at Dublin, he established himself in practice in Belfast, and was at the same time appointed to teach chemistry in the Royal Belfast Academical Institution. During ten years he was occupied in this way, and gradually became known to the scientific world as the author of valuable papers on subjects connected with voltaic action and heat of combination.

In 1845 Andrews was appointed vice-president of the Northern College (now Queen’s College, Belfast), and resigned both his teaching position and his private practice. In 1849 came the opening of the Queen’s Colleges, in the organisation of which Andrews had been engaged since 1845, and he was then appointed to the professorship of chemistry in Queen’s College, Belfast, a post which he only resigned in 1879. During the intervening period, while occupied with the affairs of his college and the duties of his chair, he was constantly engaged in scientific research, and published numerous valuable memoirs.

After his resignation of the offices of vice-president and professor of chemistry in Queen’s College, he lived in great retirement in Fort William Park, Belfast. He died on 26 Nov. 1886, and was buried in the Borough cemetery, Belfast.

In 1842 Andrews married Jane Hardie, daughter of Major Walker of the 42nd highlanders, by whom he had four daughters and two sons.

Andrews was elected a fellow of the Royal Society on 7 June 1849, and an honorary fellow of the Royal Society of Edinburgh in 1870. The degree of doctor of laws was conferred upon him by the university of Edinburgh in 1871, by Trinity College, Dublin, in 1873, and by the university of Glasgow in 1877; while the degree of D.Sc. was conferred upon him in 1879 by the Queen’s University of Ireland. He was president of the chemistry section of the British Association at Belfast in 1852, and again at Edinburgh in 1871, and was president of the association at Glasgow in 1876. In 1880 he declined an offer of knighthood. His connection with Queen’s College was commemorated by the establishment after his death of an Andrews studentship, and his portrait was placed in the examination hall of the college.

Andrews published no less than fifty-one scientific papers, the list of which is to be found in the ‘Royal Society’s Catalogue.’ His most important researches were those dealing with heat of combination, ozone, and the continuity of the gaseous and liquid states of matter.

The researches on heat of combination, carried out from 1841 to 1869, dealt with a great variety of chemical reactions and exhibited a degree of precision far in advance of that of previous workers in the same field, this being largely due to his improved experimental methods. The experiments on ozone, which were partly carried out in conjunction with P. G. Tait, finally established the fact that this substance, which was discovered by Schönbein in 1840, is simply an allotropic form of oxygen, and is a perfectly definite substance, which can be prepared in a number of different ways. This work moreover laid the basis for future researches by which the exact relation of this remarkable gas to the simpler oxygen was finally ascertained.

By far the most brilliant and far-reaching of Andrews’s discoveries, however, was that of the existence of a critical temperature, above which a gas cannot be converted into a liquid by pressure, however great. The records of the behaviour of carbonic acid gas under varying temperatures and pressures, which were made by Andrews, have become classical, and have served as the foundation of all the more recent work on the relations of the gaseous and liquid states of matter. These researches moreover pointed out the fundamental condition for the liquefaction of all gases. This cannot be accomplished unless the temperature of the gas is below the critical temperature, and it is by the recognition of this fact that later experimenters have been able to bring about the reduction to the liquid state of all known gases, a work which has only recently been completed by the liquefaction of hydrogen.

Andrews is described by his biographers as personally a man of simple unpretending manner, thoroughly trustworthy and warm-hearted. In his laboratory he was distinguished by great manipulative dexterity. He took a great interest in social questions, as is evidenced by a paper upon the temperance