Monazite, a phosphate of thorium and other rare earths, contains on the average about i cc. per gram.
The extraction (as is the case with all the rare earths) is a matter of great difficulty.
The movements of the shaft are controlled by relays and electro-magnets which operate in response to the action of the subscriber whose telephone is fitted with a 'calling mechanism which, when the subscriber calls, earths the line a certain number of times for each figure in the number of the wanted subscriber.
Our regions will not be natural unless they mark out real discontinuities both of origin and affinity, and these we can only seek to explain by reference to past changes in the earths history.
To quote further: Existing floras exhibit only one moment in the history of the earths vegetation.
The great primary divisions of the earths flora present themselves at a glance.
The later period of the Mesozoic era saw the almost sudden advent of a fully developed angiospermous vegetation which rapidly occupied the earths surface, and which it is not easy to link on with any that preceded it.
This aggregation of genera and of endemic species is characteristic of the circumferential portions of the earths land surface: the expansion of the one and the further advance of the other is arrested.
Such a summary of the salient facts in the, geographical distributio~ of plants sufficiently indicates the tangled fabric of the earths existing floral covering.
Under such circumstances the earths vegetation would be very different from what it is, and the study of plant distribution would be a simple affair.
It is true that the earths physical geography presents certain broad features to which plants are adapted.
The alkaline earths were assumed to be elements until 1807, when Sir H.
The former substituted for the salt, sulphur and mercury of Basil Valentine and Paracelsus three earths - the mercurial, the vitreous and the combustible - and he explained combustion as depending on the escape of this last combustible element; while Stahl's conception of phlogiston - not fire itself, but the principle of fire - by virtue of which combustible bodies burned, was a near relative of the mercury of the philosophers, the soul or essence of ordinary mercury.
1 The metals of the alkaline-earths were somewhat neglected; we find Georg Agricola considering gypsum (calcium sulphate) as a compound of lime, while calcium nitrate and chloride became known at about the beginning of the 17th century.
Berzelius's investigation of the action of the electric current on salts clearly demonstrated the invaluable assistance that electrolysis could render to the isolator of elements; and the adoption of this method by Sir Humphry Davy for the analysis of the hydrates of the metals of the alkalis and alkaline earths, and the results which he thus achieved, established its potency.
These crude earths, yttria and ceria, have supplied most if not all of the " rare earth " metals.
In 1880 Marignac examined certain earths obtained from the mineral samarksite, which had already in 1878 received attention from Delafontaine and later from Lecoq de Boisbaudran.
Taking as a basis the nature of the source of compounds, he framed three classes: " mineral," comprising the metals, minerals, earths and stones; " vegetable," comprising plants, resins, gums, juices, &c.; and " animal," comprising animals, their different parts and excreta.
Rubidium, caesium, thallium, indium and gallium were first discovered by means of this instrument; the study of the rare earths is greatly facilitated, and the composition of the heavenly bodies alone determinable by it.
(() An infusible white residue may be obtained,which may denote barium, strontium, calcium, magnesium, aluminium or zinc. The first three give characteristic flame colorations (see below); the last three, when moistened with cobalt nitrate and re-ignited, give coloured masses; aluminium (or silica) gives a brilliant blue; zinc gives a green; whilst magnesium phosphates or arsenate (and to a less degree the phosphates of the alkaline earths) give a violet mass.
A later result of this method of investigation was the discovery of a new member of the rare earths, monium or victorium, the spectrum of which is characterized by an isolated group of lines, only to be detected photographically, high up in the ultra-violet; the existence of this body was announced in his presidential address to the British Association at Bristol in 1898.
Throughout his life he paid great attention to the "rare earths" and the problem of separating and distinguishing them; in 1878 he extracted ytterbia from what was supposed to be pure erbia, and two years later found gadolinia and samaria in the samarskite earths.
The metals of the alkalis and alkaline earths, also magnesium, burn in sulphur vapour as they do in oxygen.
Their number is further increased by spatial inversion of the dicarboxylic acids formed on oxidation, followed by reduction; for example: d- and /-glucose yield d-and l-gulose; and also by Lobry de Bruyn and Van Ekenstein's discovery that hexoses are transformed into mixtures of their isomers when treated with alkalis, alkaline earths, lead oxide, &c.
It includes chalky limestones, siliceous earths, red clay, and, at the top, a layer of mudstone composed mainly of volcanic dust.
We might try our lives by a thousand simple tests; as, for instance, that the same sun which ripens my beans illumines at once a system of earths like ours.