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In cases of the most common tools, data relating to the weights, costs, and prices have, in several instances, been given, as nearly as it has been found possible to strike the average ruling in this country. Although these figures may slightly fluctuate in any particular neighbourhood, and may vary somewhat in different districts, such details as are supplied will often be acceptable as a guide in agreeing for, purchasing, and valuing tools.
The writer is persuaded that a more general diffusion of knowledge regarding the special forms of mining tools used for particular work, in different districts and countries, must be advantageous. Consequently, various tools more or less peculiar to different localities, and also some foreign tools, have been illustrated. Instances are occasionally to be seen of miners working under unfavourable circumstances through being uninformed regarding tools used in a remote district.
The illustrations-drawn to scale-may be found convenient to some for reference, when requiring an insight into the character of details belonging to our subject, which, amongst mining and manufacturing circles, and in engineering
publications, are often alluded to in technical
The foregoing remarks summarize the purport of this little book. It has been written in the midst of busy occupation in mining and mechanical pursuits a circumstance which, almost as a natural consequence, has added to its imperfections.
Simple as the subject appears, it was adopted because the need of some work devoted to it has been long and often expressed. Should this publication in a small measure tend to promote the miner's important calling, its production will be significantly honoured.
Any suggestions or additional information will be highly esteemed by the writer.
BRISTOL SCHOOL OF MINES,
IN noticing some points pertaining to iron and steel—which have become indispensable in the manufacture of most of the tools and implements now employed in the industrial arts-it will neither be necessary to enumerate the many different kinds of iron ores met with, nor to consider the various systems pursued for winning or working them. Many of our readers will be more or less acquainted with the processes by which iron is reduced from its ores and manufactured into a saleable product. Reference will be made to some of these processes, but only so far as partly to account for the differences between good and bad iron and steel; and, further, to explain briefly some chemical and other facts to such readers as may not have acquired much technical training.
The purest state in which the metal iron can be generally obtained is that known as wrought71
iron. Absolutely pure iron is a chemical curiosity. The best bar-iron has traces of other elements, some chemically combined, and others mechanically alloyed with it; but they appear to have no very positive influence upon the quality of the iron until their quantities become appreciable.
Chemical analyses have proved that, almost invariably, red-short iron contains in some form sulphur, and that cold-short iron contains phosphorus; hence, when iron is tender and weak at a red heat, or when cold, the cause is attributed to sulphur in the former case, and to phosphorus in the latter. Iron derived from the ores of some districts is noted for red-shortness; that from the ores of other districts for cold-shortness. Some ores give iron which is both red-short and cold-short. Naturally, those ores which are freest from sulphur, phosphorus, and other deleterious elements, yield pig-iron most suitable for the production of best bar-iron. The smelter reduces and separates metallic iron from the ores by slagging or scorifying the accompanying earths, metals, &c.; and during this operation it is his duty to prevent, as far as possible, the combination of any injurious element with the iron obtained. This is partially, or wholly, accomplished by introducing to the smelting furnace,