In 1756, he was appointed to the chair of chemistry and anatomy, at Glasgow; but the latter being unsuited to his taste, he exchanged it for that of medicine. In 1762, he added another new feature to chemical philosophy, by his discoveries with respect to latent heat, its connexion with fluidity, the phenomena that occur during the processes of freezing and boiling, &c.; all which he explained in the most clear and satisfactory manner. We have not space to enter fully into the nature of his investigations, but one of his propositions should be stated, in order that the reader may fully understand the term, latent heat. Water, it seems, when converted into ice, gives out 140 deg. of heat; ice, when converted into steam, absorbs about 1,000 deg. of heat, without becoming sensibly hotter than 212 deg. Philosophers had long been accustomed to consider the thermometer as the surest method of detecting heat in bodies, yet this instrument gives no indication of the 140 deg. of heat which enter into air when it is converted into water, nor of the 1,000 deg. which combine with water when it is converted into steam. Dr. Black, therefore, said that the heat is concealed (latet) in the water and steam; and briefly expressed this fact by calling the heat in that case, latent heat. This was, undoubtedly, a principal leading step to some of the grand discoveries made by Lavoisier, Laplace, and others; yet these chemists scarcely ever named Dr. Black in their dissertations; and Mr. Deluc had the impudence to claim the theory of latent heat as his own.

In 1765, he succeeded Dr. Cullen, as professor of chemistry, at Edinburgh; and the success and perseverance with which he carried on his researches,

were accompanied by a series of lectures equally remarkable for ease, elegance of style, and originality of reasoning, with novelty of information. His only publications, subsequent to this appointment, were, a paper On the Effects of Boiling upon Water in disposing it to Freeze more readily, printed in The London Philosophical Transactions for 1774; and An Analysis of the Water of some Hot Springs in Iceland, in The Edinburgh Philosophical Transactions for 1791. The latter relates, principally, to the formation of the silicious stone, which is deposited by these springs, and is considered a perfect specimen of accuracy in the analysis of mineral waters. This eminent chemist died suddenly, on the 6th of December, 1799; at which time he was a member of the Philosophical Societies of London and Edinburgh; and, what was considered a very distinguished honour, one of the eight foreign members of the Academy of Sciences of Paris. He was found dead in his chair, still holding a cup in his hand, so that his servant came into the room and went out again without, at first, perceiving he was a corpse.

The reputation of Dr. Black began to suffer, in the decline of his life, in consequence of his permitting others to pass him in the very career of discovery which he had opened. This arose, in a great measure, from the almost entire devotion of his time to the duties of his lectureship; and with such distinguished eminence did he fill the chair, that few gentlemen left Edinburgh without having attended a course or two of Professor Black. His private character was highly estimable, and few men have died more respected in the Scotch metropolis.

MATTHEW

MATTHEW BOULTON was born at Birmingham, on the 14th of September, 1728, and after having received a tolerable education, studied drawing and inathematics. He commenced business as a manufacturer of hardware; and, having discovered a new method of inlaying steel, he sent a considerable

BOULTON.

quantity of buckles, watch-chains, &c. to the continent, where they were purchased by the English, as the offspring of French ingenuity. Finding his premises at Birmingham not sufficiently capacious for his purposes, he, in 1762, purchased an extensive tract of heath, about two miles from the town, and at

own account, in the town of Leicester. His religious doctrines, it is said, operated against him, and prevented him from obtaining much employment in his profession. He struggled, however, says his biographer, "against pecuniary difficulties with economy; and shielded his peace of mind against bigotry, in himself or others, by looking through nature up to nature's God.'' In other words, he had imbibed a taste for natural history, to which he devoted the principal part of his time; and so early as the year 1750, he appears to have communicated some papers to The Gentleman's Magazine. To this periodical he continued to be a contributor for a period of fifty years, and some of the most valuable articles which it contains, relative to botany, are from his pen. Among those written by Dr. Pulteney, the principal are, A Series of Letters on the Poisonous Plants of this Country; A Brief Dissertation on Fungi in general; A Series of Experiments and Observations, to Shew the Utility of Botanical Knowledge in relation to Agriculture and the Feeding of Cattle; an abstract of a Latin treatise, published by Linnaeus, and entitled Somnus Plantarum (The Sleep of Plants); An Account of the First and Second Volumes of a New and Enlarged Edition of Professor Linnaeus's Systema Naturæ ; On Tremella Nostoc; On the Orcheston Grass; Account of the Flora Rossica; On Myrica Gale; The Aërostatica described; On Tri

chitae.

The importance of the above communications will be at once acknowledged, when it is recollected that, at the time when they were written, the pursuit of natural history, in England, was confined to a very few persons, and an acquaintance with the principles of the Linnæan system, to stiil fewer. The Somnus Plantarum, mentioned above, was afterwards treated, by the subject of our memoir, in an enlarged and more scientific manner, and obtained insertion in the Philosophical Transactions, under the title of Some Observations upon the Sleep of Plants; and an account of that faculty which Linnæus calls Vigilia Florum, with an enumeration of several plants which are subject to that law. For these papers, and a previous communication

relative to the rare plants of Leicestershire, our author was, in 1762, admitted a member of the Royal Society. The president of this learned body, at that time, was the Earl of Macclesfield, to whom Dr. Pulteney was introduced, besides several other distinguished characters, who not only admired his scientific knowledge, but intimated a desire to encourage him in his professional career. In consequence of this, he proceeded to Edinburgh; and, in 1764, graduated M. D., his inaugural dissertation being entitled Cinchona officinalis; a subject which he treated with so much ability, that it was afterwards inserted in the third volume of The Thesaurus Medicus.

On his return to London, Dr. Pulteney was introduced, by the celebrated Mrs. Montagu, to the Earl of Bath, who acknowledged him as a relation, and appointed him his travelling physician. The death of his patron taking place soon after, he removed to Blandford, in Dorsetshire, and there commenced medical practice under very favourable circumstances. His professional merit soon became conspicuous; and, in a few years, his circuit included not only the whole of his own county, but also the contiguous parts of Wiltshire, Hampshire, and Somersetshire. In 1779, he married a Miss Galton, a lady of superior attainments, but by whom he never had any children.

In 1781, he published his General View of the Writings of Linnæus, one of the most popular botanical publications which ever appeared in this country. "Sanctioned by the commendations," says his biographer, Dr. Maton, "of all who were already conversant with its subjects, the work soon attracted general curiosity: the labours of Linnæus and the sciences to which they related, became much more correctly understood; and Dr. Pulteney found himself placed among the first, both of the Linnæan scholars and of the philosophical naturalists of his country." The work sold extensively; and, in 1789, was translated into French, by L. A. Millin de Grandmaison. Royal Academy of Sciences of Stockholm, testified their approbation of it, by presenting the author with two medals, struck in honour of Linnæus; one by command of the King of Sweden,

The

and the other at the expense of Count Tessin.

In 1784, he was chosen an honorary member of the Royal Medical Society of Edinburgh; and, in 1787, of the Chirurgical and Obstetrical Society of that city, and also of the Medical Society of London. In 1790, he published a more original and laborious work than the last, under the title of Historical and Biographical Sketches of the Progress of Botany in England, from its Origin to the Introduction of the Linnæan System. This, though abounding with original and valuable information, does not contain all that might have been collected on the subject; a defect of which the author himself seems to have been well aware. "I have no expectation," he said, in a letter to a friend, "that a book of this nature will come to a second edition, in my lifetime; after I am gone, somebody will take it up and make a good work of it, now I have led the way." Such has not yet been the case; owing, probably, as Dr. Maton observes, to the original edition not being hitherto wholly disposed of.

In 1793, Dr. Pulteney was elected a fellow of the Royal Society of Edinburgh. Of the Linnean Society he had been elected a fellow from its earliest institution, and was a most valuable contributor to its Transactions. Among his communications may be mentioned, Description of a Minute Epiphyllous Lycoperdon, discovered on the Leaves of Anemone Nemorosa; Observations on the Economical Use of Ranunculus Aquatilis, with Introductory Remarks on the acrimonious quality of some of the English species of that genus; and On Ascarides discovered in the Intestines of Pelicanus Carbo and Cristatus. His medical papers, in the Philosophical Transactions, are, The Case of a Man whose Heart was found enlarged to a very Uncommon Size; Concerning the Medical Effects of a Poisonous Plant (Enanthe crocata), exhibited instead of the Water-Parsnip; and An Account of Baptisms, Marriages, and Burials,

during Forty Years, in the Parish of Blandford Forum. He also wrote some professional papers in The Memoirs of the Medical Society of London, and in The Medical Observations and Inquiries. His principal contribution to the former publication is entitled, Case of an Extraordinary Enlargement of the Abdomen, owing to a Fleshy encysted Tumour. As an antiquarian, also, Dr. Pulteney displayed considerable re search and skill. He was a liberal contributor to Dr. Aikin's England Delineated, and Mr. Nichols's History of Leicestershire. Archdeacon Coxe profited by his valuable communication on subjects relating to natural history, and his conchological knowledge was exhibited in the assistance which he rendered to M. Da Costa, in the compilation of his British Conchology, and in his contributions to the History of Dorsetshire. He died, on the 7th of October, 1801, of a pulmonary complaint, with which he had been afflicted at an early period of his life. Out of an affluent fortune, he made liberal benefactions to several charitable institutions, and left to the Linnæan Society his valuable Museum of Natural History. In 1805, appeared a second edition, with corrections, considerable additions, and memoirs of the author, by W. G. Maton, M. D.

The character of Dr. Pulteney was estimable and amiable in a very high degree, and no man ever had friends more strongly attached to him, or was more generally respected by his numerous acquaintances. His manner was cheerful and urbane, and his countenance bespoke the simplicity, candour, and liberality of his mind. His ardour for science never forsook him; and he was as zealous in the pursuit of it at the close of his life as at the commencement of his professional career. His conversation, like his morals, was spotless; his religion unaffected, and devoid of bigotry or intolerance, the only failings in others, which he is said to have contemplated without sympathy or indulgence.

VOL. III.

HENRY CAVENDISH, son of Lord Charles Cavendish. a younger brother of the Devonshire family, was born at Nice, in Piedmont, on the 10th of October, 1731. He received the rudiments of education at a private academy, at Hackney, and completed it at the University of Cambridge, where the pursuits of philosophy and chemistry engrossed the chief portion of his time. His natural temper, and pecuniary circumstances, which were narrow, during his father's life, concurred in strengthening his disposition to study and retirement; so that his habits underwent but little alteration, when he became inheritor of a large property. On leaving college, the above sciences continued to be the subject of his investigations, which a constitutional coldness of feeling enabled him to carry on with a caution, patience, and perseverance, that greatly accelerated his discoveries.

The Newtonian philosophy early engaged his attention, and having mastered the principles, he applied them to an explanation of the laws of electricity. He only wrote two papers on this subject, the result, however, of very elaborate investigation, and respectively entitled An Attempt to explain some of the Principal Phenomena of Electricity, by means of an Elastic Fluid; and An Account of a Set of Experiments to determine the Nature of the Shock communicated by the Torpedo. In the latter, he explained the singular properties of electrical fishes; showing that distinction between common and animal electricity, which has been confirmed by the subsequent discovery of galvanism. The calculation of a remarkably luminous arch, seen in February, 1784, formed the subject of one of his meteorological communications to the Transactions of the Royal Society; and another contained an account of the meteorological instruments, belonging to that body, with remarks on their use and construction. It need scarcely be observed, that he was one of its most distinguished members, as well as one of the most valuable contributors to its

Transactions, to which he consigned the whole of his scientific writings.

The chief of these are his papers on chemistry, the first of which appeared in The Philosophical Transactions for 1766, entitled Experiments on Factitious Airs. In this he gives an account of his examination of fixed and inflammable air, which ended in his discovery of the extreme comparative levity of the latter; thus laying the foundation of the practice of aërostation. In a subsequent paper, he proves the interesting fact of the solubility of lime and magnesia in water, by means of fixed air, the result of his experiments on some mineral water, at Rathbone Place. His determination of the proportion of oxygen and of azotic gas, in the compo. sition of atmospherical air, forms the subject of another paper. His observation of the congelation of quicksilver, having turned his attention to the subject of freezing in general, he instituted a variety of experiments, which he explained in two papers, constituting one of the most interesting parts of the theory of heat. In fine, his chemical writings may be said to contain five valuable discoveries, all little short of perfection :-Firstly, the nature and properties of hydrogen gas; secondly, the solvent of lime in water, when it is deposited by boiling; thirdly, the exact proportion of the constituents of common air, and the fact that the proportion never sensibly varies; fourthly, the composition of water; and, fifthly, the composition of nitric acid. The last paper he wrote was A Method of dividing Astronomical Instruments; his other astronomical communications are, The Civil Year of the Hindoos, and its Divisions; A Rule for finding the Longitude by the Lunar Observations; and An Account of Experiments to determine the Density of the Earth.

This eminent philosopher, to whose discoveries science is indebted for the explanation of so many natural phenomena, died at his residence on Clapham Cominon, on the 24th of February, 1810; leaving property, it is said, to the