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By T. A. Rickard

The lodes of Cripple Creek, Colo., partake of the composition of the geological formation which they traverse. The prevailing rocks are andesitic breccia, lying upon granite, and also bodies of phonolite, trachytic phonolite, nepheline-basalt, etc., penetrating both the granite and the breccia. At Kalgoorlie, in West Australia, the prevailing rock is schistose, and has not been certainly identified, though microscopic sections indicate the probability that it was originally an acid eruptive. The lodes are essentially bands, more highly schistose than the encasing rock, and impregnated to a notable degree with disseminated pyrites and secondary calcite. During 1899 Cripple Creek produced 425,590 tons of ore, having a gross value of $15,658,254; during the same period the output of Kalgoorlie was 467,048 tons, valued at $17,724,587. In chemical composition, the ores at Cripple Creek and Kalgoorlie, respectively, present differences equally interesting to the petrographer and the metallurgist. In both cases we have to deal with altered eruptives as the matrix of the ore; but the much older rock of Kalgoorlie has undergone more decompo-

Jan 1, 1901

By J. H. Bowden

The shaft-plant here described was put in operation in September, 1895, and the No. 6 slope-motor was started in May, 1896. The plant comprises : One Norwalk three-stage compressor l21/2, 91/2 and 5 in. diameters of air- and 20 in. diameter of steam-cylinder, all 24 in. stroke; capacity at 100 revolutions, 296 cu. ft. of free air per minute, compressed to 600 Ibs. per sq. in. A main pipe, 5 in. diameter, 4380 ft. long, with five charging-stations in No. 6 Shaft, and a branch of 3 in. pipe, 3100 ft. long, with three charging stations, in No. 6 Slope. These pipes on each line charge a Porter compressed-air motor, with 7 by 14 in. cylinders, and four 24 in. drivers, weighing about eight tons, with a tank-capacity of 130 cu. ft. of air at 550 lbs. pressure in the main tank, reduced to 160 lbs. in the 8-in. auxiliary tank of 4.2 cu. ft. capacity, supplying the cylinders. The No. 6 shaft run averages 4000 ft. each way on grades of $ to 23/4 per cent., and averaging close to one per cent. in favor of the loaded cars. The No. 6 slope run averages 2100 ft. with nearly the same grades. The mine-cars weigh 2800 Ibs. empty, and about 9800 lbs. loaded, and are hauled in trips of 12 to 20, averaging about 15 cars. The shaft-motor now hauls about 355, and the slope-motor 320 cars per day of 10 hours, replacing in the shaft 17 mules, and

Jan 1, 1901

Jan 1, 1901

Jan 1, 1901

By John Birkinbine

The following data, collected during a visit to the Snake river district, in Idaho, arc offered as indicating the possible utilization of a water-fall for irrigation by pumping, the working of gold-placers, the generation of electricity for light and power, and possibly for manufacturing purposes. For irriga-

Jan 1, 1901

By C. R. Van Hise

Introduction.............29 The Three Zones of the Lithosphere ..30 Zone of fracture............31 Zone of flowage............ 31 Factors influencing depth at which flowage occurs.. 32 Zone of combined fracture and flowage.. 33 The Water-Content and Openings in Rocks....36 Condition of rater in the zone of fracture.. 36 The openings in rocks...........38 Size and number of openings..... 40 Ore-deposits derived from zone of fracture..45 The source of underground water......... . 47 The cause of the flowage of underground water..47 Belts of underground circulation.. 51 Upper belt of underground circulation.. 51 Lower belt of underground circulation.. .... .52 Capacity of water for work in the lower belt of underground circulation........... 53 Movementsof water in the lower belt of underground circulation. 54 The preferential use by water of large channels.. 60 Physico-Chemical Principles Controlling the Work of Under ground Waters..........62 Chemical action............63 Underground aqueous solutions..64 The relations of solution and temperature..... 65 The relations of solution and pressure..66 Precipitation........... 67 Precipitation by change in temperature..68 Precipitation by change in pressure..69 Precipitation by reactions between aqueous solutions.. . 69 Precipitation by reactions between liquid solutions and solids. 70 Precipitation by reactions between gases and solutions. and solids............71 The General Geological work of Underground Waters.. . 71 Division of the zone of fracture into a belt of weathering and a belt of cementation............72

Jan 1, 1901

By J. B. Davis

This paper has been prepared at the suggestion of Mr. Dunbar D. Scott, to supplement his " Evolution of Mine-Surveying Instruments."† Before entering into a detailed history of solar instruments, a few remarks will be made touching upon land-surveys in general, and on what has led to the development of these instruments.The oxidation of metals melted in contact with air takes place with dissimilar results. Tin, lead or zinc are examples of a class, the oxides of which float on the surface of the melted metal. First a film is produced, which covers the surface; then, if agitation from any cause exposes new metal to the action of the air, additional oxidation takes place, and the film is increased in volume. This change goes on until a considerable quantity of oxide (or " dross," as it is technically called) is formed; depending, of course, upon the duration of the exposure of the metal to the atmosphere. When such metals are poured, the dross may be skimmed off; and clean metal will be left underneath. The removal of such oxides is, therefore, merely a mechanical process. In the case of copper, however, the result is quite different. The sub-oxide of copper (Cu2O) is readily soluble in molten copper; and therefore, instead of the formation of a film of oxide, to be finally removed as dross, the surface of the metal remains bright and clear, because the oxide has been dissolved as soon as it was produced. It is customary in the process of copper-refining to leave a small quantity of oxide in the metal, in order to oxidize any traces of bismuth, arsenic or antimony which have not been entirely removed. As a result, these metals exist in the commercial product as oxides, and not as metals, which would form an

Jan 1, 1901

At the inception of the gold-mining industry at Kalgoorlie the small supply of firewood required for steaming purposes was naturally all drawn from the limited local areas, which promised soon to become denuded. With the advent of the railway toKalgoorlie came the ever increasing machinery and steam power, and the accompanying demand for firewood so increased that the fuel contractors began their operations, by following the timber belts along the Yilgarn railway line, and graduallygetting further westward, until at present we find them as far as Woolgangie, 63 miles from Kalgoorlie, and with the regular railway rates, I0. per ton per mile, this maybe considered the limit of payable timber at current rates. Although in the early days the reserve of timber along the railway line must have appeared as incalculable and inexhaustible as that of coal did in Europe a couple of centurys ago, the day is now near us when even this source will fail to meet the demands made upon it, for, although a good two years' supply is available or the areas under the axe, yet it is time to look ahead and find from whence the future supplies are to be drawn. Along the railways we find the zone of felling operations limited for want ofcommunication, and only such portions of the forests as are within six or seven miles of the railway come under the axe at present while virgin forests to the rear remain practically unexploited. It is only in the course of the past sixteen months that the firewood industry has developed...

Jan 1, 1901

The sulphide ores of the principal lodes of the Boulder Mines are mainly composed of a schistose guess with a varying proportion of silica and lime, containing tellurides of gold, silver and mercury, associated with iron pyrites. It is a great difficultyto obtain pure and homogeneous samples of the tellurides for analysis, and from a number of tests made with excellent specimens it was found hardly possible to procure two to agree in analysis, the precious metals being found to be combinedwith tellurium in most varying proportions indeed, a close inspection of a partially crushed specimen will reveal, even to the naked eye, the various shades of colour characteristic...

Jan 1, 1901

Jan 1, 1901

Prof. Henry M Howe, New York: It is extremely probable that this efflorescence of silica is due to the liquation either of silicon or of a silicide, and the subsequent oxidation of the silicon to silica. As Mr. Fackenthal says, it is very hard to see why silicon should liquate from an iron containing so little silicon, and it seems more probable that some silicide of some volatile element has liquated, and has dissociated on reaching the air, and that the volatile element has volatilized, leaving the silicon to oxidize to silica. The volatile elements present which might thus liquate in combination with the silicon are sulphur, zinc, and lead. It is hard to see why sulphide of silicon should have liquated from an iron containing so little of either sulphur or silicon. At first, one naturally thinks that either the zinc or the lead present in this furnace might have liquated as silicide. It is true that they are both volatile at the temperature within the furnace, but then the vapor-tension* of each of them within

Jan 1, 1901

Beverley S. Randolph, Frostburg, Md. (communication to the Secretary): It has always appeared to me that each coalseam has its peculiar character or habit, due to the conditions of its formation, by virtue of which it is either persistent or variable in its section over extended areas. One seam will hold its thickness, chemical character, number and position of partings, beds of slate, etc., over a large area, while another will be found to vary in some of these characteristics every few feet. As the position of the outcrop is an accident of the topography, depending on folding and erosion which have taken place since the bed was formed, no one opening in the outcrop, or, in fact, anywhere else, can supply reliable evidence as to the general character of the seam. To determine the character of an untried seam, a number of sections are necessary from widely separated points, in order to show such variations as may exist. Should material variations be developed, more numerous sections are necessary, in

Jan 1, 1901

By John Birkinbine

Secretary's Note.—In printing this paper in the present volume, the figures given in the pamphlet edition have been brought more nearly up to date, the product of 1899 being in many instances inserted. Iron-Ore Resources. In a paper presented to the Institute in 1897,* I discussed the iron-resources of the United States as then developed, calling attention to some principal sources upon which other countries depended. The following statement will give a general idea of the amounts, as compiled from the latest official records, of ores won, and metal produced, in the nations which are important contributors to the world's output. Unfortunately these are not all contemporaneous, since in some countries the statistics do not appear until after one or more years. The statement covers not only pig-iron and iron-ore, but also manganese-ore —the manganese mined being principally used in the production of spiegeleisen or ferro-manganese, and these alloys being generally included in the pig-iron output. Table I, which epitomizes the present situation, shows respectively the countries and the quantities of iron-ore and man-

Jan 1, 1901

Jan 1, 1901

In discussing Mr. Keller's paper, I quoted the results obtained by Mr. Allan Gibb, correctly crediting them to Mr. Gibb, with due reference to the report in which they were published. But in the table immediately following, and in my further remarks, following the table, I find that, by some clerical or other error which I cannot, after the lapse of time, explain, I spoke of Mr. Gibb as Mr. "Dean"—a metallurgist who had written on a related subject, but not on the point I was discussing. In short, my reference throughout was to the work of Mr. Gibb; and by reading a Gibb " for a Dean " in all places on pp. 832 and 835 where the latter name occurs, my remarks will be brought into accordance with my intention, and with the facts.

Jan 1, 1901

W. S. GRESLEY, Erie, Pa. (communication to the Secretary): A six-entry method of opening coal-mines is, or was a short time ago, practiced in the Connellsville coal-region; but Dr. Chance's method has a novel aspect; for while in the Connellsville region the main pillars are formed outside of two pairs

Jan 1, 1901

Fred. T. Greene, Rossland, B. C. (communication to the Secretary): At the beginning of his gaper, Mr. Herzig refers to an article of mine in the Engineering and Mining Journal of January 27, 1900. I would like to add that the method de-

Jan 1, 1901

A. R. Ledoux,New York City: The so-called combination method " is generally used in assaying bar copper for silver. It has been modified from time to time. Briefly outlined

Jan 1, 1901

H. Van F. Furman, Denver, Colo. (communication to the Secretary): There are some statements in Dr. Carpenter's interesting paper which appear to require explanation, if not modification.

Jan 1, 1901

George L. Heath, South Lake Linden, Mich. (communication to the Secretary): In presenting some notes on the "Heine's Blue Test" Mr. Smith expresses a preference for fresh standards and a cheaper bottle; but this is rather a reversion to the old method, since I devised in 1897 the newer method of preparation and preservation of' permanent standards, which were not used with any success in the original method. Many busy western assayers no doubt value a method for preparing a permanent set of standards in air-tight glass-stoppered bottles, whose use brings the method as near perfection as one could desire as regards rapidity of color-reading and avoidance of unnecessary work. Mr. Smith notes that his color-readings were compared with an electrolytic assay of another ore-sample, and that my electrolytic assays were made on the " blue test" solution from colorimetric assay. He omits, however, reference to the fact, showing the advantage of my procedure, that the next column in table of

Jan 1, 1901