CONTENTS OF No. LV. I. THE CHEMISTRY OF THE FUTURE. II. ON THE PROBABLE ORIGIN AND AGE OF THE SUN. By James Croll, LL.D., F.R.S., of H.M. Geological Survey III. THE GLACIAL PERIOD IN THE SOUTHERN HEMISPHERE. By NOTICES OF SCIENTIFIC WORKS. Thomé's "Text-Book of Structural and Physiological Botany.". 416 Woodward's "The Geology of England and Wales." Goodeve and Shelley's "The Whitworth Measuring-Machine, in- cluding Descriptions of the Surface-Plates, Gauges, and other Measuring-Instruments, made by Sir Joseph Lord Rayleigh's "Theory of Sound." PAGE Thearle's "Theoretical Naval Architecture: a Treatise on the Angell's" Elements of Magnetism and Electricity." Battye's "What is Vital Force? or a Short and Comprehensive Temple's "Aids to Chemistry, specially designed for Students Taylor's "The Aquarium, its Inhabitants, Structure, and Management." . 421 422 422 422 423 423 Including Proceedings of Learned Societies at Home and Abroad, and Notices of Recent Scientific Literature. PHYSICS MICROSCOPY 428 432 THE QUARTERLY JOURNAL OF SCIENCE. JULY, 1877. I. THE CHEMISTRY OF THE FUTURE. N selecting this subject we lay no claim either to the gift of second sight or to the possession of a clearer view of the future development of Science than may be the lot of our contemporaries. Nor is it our purpose to write an imitation of Winterl's celebrated "Prodromus," in which enthusiasts may find whatever they think proper. We seek merely to call the attention of our fellow-workers, and especially of students, to certain researches which hold out great promise, and which, if duly followed up, will undoubtedly have a most important influence on the very foundations of chemistry. It must be confessed that, as regards these very foundations, the alphabet of the science, our knowledge is not merely limited, but unsatisfactory in the highest degree. Look at our "elements." Most chemists quietly accept them as ultimate facts, and work with them-or perhaps play with them-more or less judiciously, quietly waiving all inquiry into their nature and their origin. Are they absolutely elementary bodies, distinct from the beginning, and resolvable neither into each other nor into any forms of matter still unknown? Or are they compounds, elementary in the mere relative acceptation that their decomposition is a task not within our present knowledge and power. Have we any evidence of their simplicity other than what our grandfathers had of the supposed elementary character of potash and soda prior to Davy's great discovery? If compounds, are they all of the same order, or are some of them, perhaps, resolvable into the remainder, whilst these, in turn, consist of ultimate-or at least ulterior-bodies, as yet undiscovered? If simple, are they like the wheels and pinions VOL. VII. (N.S.) U of a machine, or the parts of a dissected puzzle, definite in their number and purpose, and all necessary to a given result? Or are they a mere fragmentary and accidental group of objects with which we build our Lagerungs formel, just as children construct their sand forts and shell grottoes on the shore? What would be the impression of a man of inquiring mind if for the first time made acquainted with the so-called elements and their leading properties? He would see a list of some sixty bodies, from which, he is told, all things visible or tangible-all matter, in short-are compounded. But why their number should be between 60 and 70, rather than between 30 and 35 or between 160 and 170, no reason is given or even conjectured. Some of them, he is informed, such as oxygen, hydrogen, nitrogen, silicon, aluminium, and sulphur, are exceedingly abundant. Others, on the contrary,-as vanadium, thallium, indium, cæsium, and gallium, occur only in minute traces. Some are widely distributed, and others concentrated in comparatively few localities. Turning to their properties he finds equal difficulties. Here he will see a number of "elements" identical, or at least closely approaching, in their atomic weights. There, on the contrary, he finds wide gaps. Thus betweeen cerium (140) and erbium (178) there intervenes not an element. A smaller blank is found between bismuth (208) and thorium (231), between tungsten (184) and osmium (195), between zinc (65) and arsenic (75); whilst, on the contrary, between 86 and 96 we number six elements, and between 195 and 200 five (see Table I.). These gaps may, indeed, be possibly filled up by the discovery of some rare element, but there is also the possibility that new discoveries may fall in the more thickly-filled parts of the series. With those properties of the elements which cannot as yet be exhibited in a numerical series the case is very similar. There are groups showing a close approximation in their characters and behaviour. There are elements which stand comparatively isolated. How are all these facts to be explained on the theory of elements primordially distinct? Popular opinion, here as elsewhere, takes refuge in teleology. The elements in their respective proportions and in their distribution exist, as we find them, for the sake of man's convenience. We demur to this hypothesis. Look at sulphur; where existing in quantity the very key with which we unlock the treasurehouse of Nature-no less essential to the chemical technologist than is iron to the engineer; but where occurring in small quantities, what a source of evil! Take the case of |