Part 7 (1/2)

It is interesting to note also that it was obtained, at an ancient period, from the oil-fountains of Is, and that it was put to considerable use in the eyptians It appears, too, to have been employed in the construction of the walls of Babylon, and thus from very early tietation have been brought into use for the service of man

Aniline has been previously referred (p 135) to as having been prepared from nitro-benzole, or _essence dethis substance with iron-filings and acetic acid, was one of the early triumphs of the chemists who undertook the search after the unknown contained in gas-tar It had previously been obtained from oils distilled from bones The importance of the substance lies in the fact that, by the action of various chereat richness are formed, and these are the well-known _aniline dyes_

As early as 1836, it was discovered that aniline, when heated with chloride of lime, acquired a beautiful blue tint This discovery led to no immediate practical result, and it was not until twenty-one years after that a further discovery was made, which may indeed be said to have achieved a world-wide reputation It was found that, by adding bi+chromate of potash to a solution of aniline and sulphuric acid, a poas obtained from which the dye was afterwards extracted, which is known as _mauve_ Since that time dyes in all shades and colours have been obtained froenta_ was the next dye to make its appearance, and in the fickle history of fashi+on, probably no colours have had such extraordinary runs of popularity as those of enta Every conceivable colour was obtained in due course froan to suspect that, in the course of ti matter of dyer's madder, which was known as _alizarin_, would also be obtained therefrom Hitherto this had been obtained from the root of the madder-plant, but by dint of careful and well-reasoned research, it was obtained by Dr Groebe, from a solid crystalline coal-tar product, known as _anthracene_, (C_{12}H_{14}) This artificial alizarin yields colours which are purer than those of natural arded as a waste product, its cost of production is considerably cheaper

We have endeavoured thus far to deal with (1) gas, and (2) tar, the two principal products in the distillation of coal We have yet to say a feords concerning the useful ammoniacal liquor, and the final residue in the retorts, _ie_, coke

The a distillation of the coal, and which has been collecting in the hydraulicapparatus, is set aside to be treated to a variety of chemical reactions, in order to wrench frost these, of course, _a comparatively unimportant In order to obtain this, the liquor is first of all neutralised by being treated with a quantity of acid, which converts the principal constituent of the liquor, viz, carbonate of a salts), into either sulphate of ammonia, or chloride of a as sulphuric acid or hydrochloric acid is the acid used Thus carbonate of aive sulphate of aive sal-ammoniac (chloride of ammonia) By a further treatment of these with lime, or, as it is chemically known, oxide of calcium, ammonia is set free, whilst chloride of liypsum, or ”plaster of Paris” ), is the result

Thus:

Sulphate of ammonia + lime = plaster of Paris + ammonia

or,

Sal-ammoniac + lime = chloride of lias, and acts rapidly upon the eyes It has a sti effect upon the nerves It is not a cheen by weight to one of nitrogen, both of which elements alone are very harmless, and, the latter indeed, very necessary to hureat irritation of the lungs

It has also been called ”hartshorn,” being obtained by destructive distillation of horn and bone The name ”ammonia” is said to have been derived from the fact that it was first obtained by the Arabs near the temple of Jupiter Ammon, in Lybia, North Africa, from the excrement of camels, in the form of sal-ammoniac There are always traces of it in the ate towns and e quantities of coal are burned

coke, if properly prepared, should consist of pure carbon Good coal should yield asto the unsatisfactory manner of its production, this proportion is seldom yielded, whilst the coke which is fa the residue left in the retorts after gas-e a proportion of sulphur as to make its combustion almost offensive No doubt the result of its unsatisfactory preparation has been that it has failed to make its way into households as it should have done, but there is also another objection to its use, naen required in its cos of suffocation where insufficient ventilation of the rooe quantities of coke are, however, consu of boilers of locoical operations; and in order to supply the dee quantities of coal are ”coked,” a process by which the volatile products are co behind This process is therefore the direct opposite to that of ”distillation,” by which the volatile products are carefully collected and re-distilled

The sulphurous impurities which are always present in the coal, and which are, to a certain extent, retained in coke as-works, themselves have a value, which in these utilitarian days is not long likely to escape the attention of capitalists In coal, bands of bright shi+ning iron pyrites are constantly seen, even in the homely scuttle, and when coal is washed, as it is in some places, the removal of the pyrites increases the value of the coal, whilst it has a value of its own

The conversion of the sulphur which escapes froen, and then into sulphuric acid, or oil of vitriol, has already been referred to, and we can only hope that in these days when every available source of wealth is being looked up, and when there threatens to re which shall in the future be known as ”waste,” that the ater the receptacle for the unowned and execrated brimstone of millions of fires and furnaces

CHAPTER VII

THE COAL SUPPLIES OF THE WORLD

As compared with some of the American coal-fields, those of Britain are but sarded as falling naturally into three principal areas

The northern coal-field, including those of Fife, Stirling, and Ayr in Scotland; culand; Tyrone in Ireland

Thethose of Yorkshi+re, Derbyshi+re, Shropshi+re, Staffordshi+re, Flint, and Denbigh

The southern coal-field, including South Wales, Forest of Dean, Bristol, Dover, with an offshoot at Leinster, &c, and Millstreet, Cork

Thus it will be seen that while England and Scotland are, in comparison with their extent of surface, bountifully supplied with coal-areas, in the sister island of Ireland coal-producing areas are almost absent The isolated beds in Cork and Tipperary, in Tyrone and Antrim, are but the re the whole breadth and length of Ireland Such beds as there re to the base of the coal-o to show that the surface suffered such extrerowth of the coal-forests, that the wealth which once lay there, has been swept away from the surface which formerly boasted of it

On the continent of Europe the coal-fields, though not occupying so large a proportion of the surface of the country as in England, are very far froarded The extent of forest-lands still re for the immediate needs of the districts where some of the best seams occur It is only where there is a dearth of handy fuel, ready to be had, perhaps, by the si into the earth for his fuel But although on the continent not yet occupying so prominent a position in public estimation as do coal-fields in Great Britain, those of the forreat thickness of some of the individual seams