The mention of graphite brings us to the next stage. Graphite, plumbago, or, as it is more commonly called, black-lead, which, we may say in passing, has nothing of lead about it at all, is best known in the shape of that very useful and cosmopolitan article, the black-lead pencil. This is even purer carbon than anthracite, not more than 5 per cent. of ash and other impurities being present. It is well-known by its grey metallic lustre; the chemist uses it mixed with fire-clay to make his crucibles; the engineer uses it, finely powdered, to lubricate his machinery; the house-keeper uses it to "black-lead" her stoves to prevent them from rusting. An imperfect graphite is found inside some of the hottest retorts from which gas is distilled, and this is used as the negative element in zinc and carbon electricity-making cells, whilst its use as the electrodes or carbons of the arc-lamp is becoming more and more widely adopted, as installations of electric light become more general. One great source of true graphite for many years was the famous mine at Borrowdale, in Cumberland, but this is now almost exhausted. The vein lay between strata of slate, and was from eight to nine feet thick. As much as £100,000 is said to have been realised from it in one year. Extensive supplies of graphite are found in rocks of the Laurentian age in Canada. In this formation nothing which can undoubtedly be classed as organic has yet been discovered. Life at this early period must have found its home in low and humble forms, and if the _eozoön_ of Dawson, which has been thought to represent the earliest type of life, turns out after all not to be organic, but only a deceptive appearance assumed by certain of the strata, we at least know that it must have been in similarly humble forms that life, if it existed at all, did then exist. We can scarcely, therefore, expect that the vegetable world had made any great advance in complexity of organism at this time, otherwise the supplies of graphite or plumbago which are found in the formation, would be attributed to dense forest growths, acted upon, after death, in a similar manner to that which awaited the vegetation which, ages after, went to form beds of coal. At present we know of no source of carbon except through the intervention and the chemical action of plants. Like iron, carbon is seldom found on the earth except in combination. If there were no growth of vegetation at this far-away period to give rise to these deposits of graphite, we are compelled to ask ourselves whether, perchance, there did not then exist conditions of which we are not now cognisant on the earth, and which allowed graphite to be formed without assistance from the vegetable kingdom. At present, however, science is in the dark as to any other process of its formation, and we are left to assume that the vegetable growth of the time was enormous in quantity, although there is nothing to show the kind of vegetation, whether humble mosses or tall