Volume 26 (1873) (431 pages)

82 MINING AND SCIENTIFIC PRESS. {February 8, 1873. (GORRESPONDENCE. Case-Hardening. Written for the Press. It ie a very obvions fact, that a hard-working surface will last very much longer than a oft one, hesides doing away to a very greet extent, with the likelibood of the two surfaces cutting or seizing —thet bugbeer of all engineers. I have seen.the elide-valves and velve-seets of locomotive engines so soft, that face them down ever so true, before they bad run for e month, the seet would be worn en eighth of an inch hollow, and the valve correspondingly round, on tbe surface, thus destroying very meterially the working power of the engine, as it would be impossible in euch a cese for the engine either to receive, cut off, or emit her steam with tbe precision that is reqnired. The valve motion, too, may be closed, all loet motion teken out of pins, pin-holes, ete., but the metel being soft, or merely smeared over with potash, will, before the engine has made many trips, give so much end wear away so quickly, that it looks like a nseless expenditure of labor either to repair or make machinery and send it ont to work in that style. How, then, is it to be avoided ; whet shell be done to remedy the evil ? As far as cast-iron is concerned, of conrse notbing cen bedoue toward meking that herder then if naturelly is; but there is a procese by which wrought iron cen be mede so extremely hard as to equal herdened steel—thet process is case-hardening. I heve been surprised to find thie so mnch neglected both in the Eastern Stetes and on the Pecific Slope. The process is eo simple, and can be done with so little -expense thet, considering tbe immense adventages to be gained, it bas been a wonder to me why there was not a case-bardening furnace put upatall machine shops. I have essisted et casehardening in Europe and also in this country, and for the benefit of mechanics and the trade generally, I will give, in es clear a way as I can, the result of my obeervation and experience, Afurnece shonld be constructed of stone, well cemented together, walls not less than one foot in thickness; the size of furnace, of course, would be mede to suit the qnentity of work each shop hed to do. Iron rods end stays should be worked in with tbe masonry across the furnace on which to lay the box, directly nunderneath being the fire space, the grate of which should stand one foot from the ground, eo as to allow a good draft nnderneeth and elso room for the ashes to fell. If not convenient to build a brickor stone chimney, stovepipe will enswer the purpose. Tbe box ehonld be made large enough to hold the different-sized pieces of metal to be hardened; but it is better to bave two boxes, rather then one too large and nnwieldly to manege; as in thet case troublo is likely to arise in getting the box out of the furnece, it being so extremely hot that it is impossible to handle it except with very long tongs, rekes, ete. The box should be made of % inch sheet iron, well riveted together with angle iron. The meterial used io mixin witb the work consists of bonee bnrned toa chercoal, with leather shevinge, burned or not burned—it does equally as well. Indeed, in some shops neither the bones nor the leather is burned at all; but cnt or mashed up very fine. This is mixed with chercoal end distributed carefully among the work to be hardened. If a piece of metal is of any coneiderablelength, cure should be taken to pack it well, for if it should rest only on its two ends it would surely get sprung in the middle, end vice versa. Ley the work carefully among the prepared stuff—one layer of stuff on the bottom of the box, then as mnch metal as can conveniently be laid down withont letting the pieces touch each other; another layer of chercoal, etc., on the top of that, eeeing that ell the various holeein the workare wellfilled; then more work, and eo on till the box is full. When fastening down the lid, it is ready for the furnace. When the door of the furnace is closed, unless it fits very close, put some fine clay all round so ae to effectually exclude all cold drafts that otherwise pass through the furnace. Some man shonld be detailed to attend to the fnrnace, and keep upa good fire, day and nigbt, so that the box is kept at dull red heat all the time. The time for keeping it in the furnaceis generally twenty-four houre. At the expiration of that time tbe box should be drawn, and cold water having been previously prepared closeby, it being kept cold by a continnous stream from hose or otherwise, the various pieces of work are picked ont and ae expeditiously as possible dropped into the water. Let me say, here, that thongh it shonld be taken from the box as quickly as poseible, to prevent the work from sealing, yet it sbonld he done with the greatest coolnese, I have have eeen men with their pokers and tongs dab into the red hot maes to wrench up from the bottom the pieces that lay there, either through excitement or ignorance, forgetting that ae the work is red hot, the smallest blow will raise a, nasty burr, which may prove tronblesome to get off afterward. A small burr raised on the edge of, or in a hole that has to work, has occasioned the necessity of softening to get it out, as itis impossible to touch work so hardened with a file of eny description. Tf the fnrnece has been ettended to properly the work will now heve a surfece ranging from 1-32 to 1-16 of an inch in thicknees, so hard thet nothing but the grindstone or emery will be eble to effect it, in making the various parts work together freely. A high and durable polish can now be pnt on by rubbing with emery cloth, andif the work has been carefully filed up, while in a soft state, it will look very nice indeed; but if, on the contrery, it has been filed too hastily or too carelessly, and deep scratches left, it will be impossible to polish it up, es the scratch will have widened and got bleck, defying the power of the polisher to make it anytbing else, buta deep, ugly seratch. The filing up work to be hardened, and leaving deep marks and putting on a high polish, to hide them for the time being after they come from the furnace, is very objectionable; it looks detestable to a practical mecbanic. Only wronght iron can be snbjected to this process. Cast iron is simply made more brittle. A master mechanic thet I wes once working for, desired me to put in the box a piece of cast iron to test the effect, stating that he thought if the hardening process wes good for wrought iron, it must he equally good for cast iron. I did es I was desired, end efter ell was cooled off I took the piece of castiron and snapped it in two with my fingers. If crank pins ere required to be hardened, tbe plain part that goes in the wheel should be well wrapped up with cley, so as to prevent as much as possible the absorption of carbon by the metal, and when cooled, they shonld be put in a trongh with water deep enongh to cover the working part, tbe other being mado to stand above the weter. MEcHanic. Carlin, Jannary, 1873. Coal for Domestic Use in San Francisco. What Kinds are Used in San Francisco—Where They Come From—Quantity, Quality, Etc. Nearly all the coal used for domestic pnrposee in California is mined on the Pacific slope. Weet Hartley is used to some extent, bunt most of thet sold by retailers for West Hartley is either mixed or entirely of eome other kind. There isno true coal fonnd west of the Rocky Mountains, with the exception of some veins on Vencouver Island, end possibly in some other portion of British Columbia. Tbe coal veins of California and Washington Territory ere of later geological formation than the enthracite beds of Pennsylvania end other Eastern Stetes. The Pacific coast production is a species of lignite, not properly coel. Anthrecite, sometimes called stone coal, is hard, bleck coel, does not soil the fingers when touched, fracture conchoidal, decrepitates in burning, kindles with difficulty, contains e very large proportion of cerbon, very little oxygen, hydrogen, and nitrogen. Bituminons, or soft coel, varies much in color, weight and quality. Some species heve a luster more waxy then that of anthacite, fracture uneven, often divided by joints into parallels; from 73 to 90 per cent. carbon, end from 8 to 22 per cent. oxygen, hydrogen and nitrogen, with considerable earthy matter and ash, The term ‘‘Bitumen” as epplied to coel does not mean that it contains minerel pitch, bnt that oxygen, hydrogen and nitrogen giveit a more inflammable cheracter. The bituminous coals are divided into sorts eccording to their burning properties, such as “‘free burning,” ‘‘smokeless,” ‘‘non-ceking,” etc. The caking coals are those which tend to partially fuse while burning, emitting smoke and jetsof ges. A single seam of coal sometimes contains layers of various quality. ~ Mount Diablo Coal. The shipments of coal from the Mount Diablo mines are larger than those of any other mine on the coast, amounting to about 180,000 perannum. The coal is used mainly for the generation of steam. It is consumed in steamers, mills, and manufacturing establishments. Some years ago, before the miners had penetrated to any great depth, the coal contained considerable enlphur, which emitted an nnpleasant odor while burning, and injured the repntation of the coal for domestic use. Since the opening of the Black Diamond, Union and Independeut veins, the quality has improved, and although little is openly sold for domestic use, it is often disposed of under other names, and the housewife does not know that she is bnrning that ‘nasty sulphur stuff.’”’ The miners are now working in solid coal, of good quality. Ahont twenty per cent. of this coal reaches the market in the form of screenings, which ie sold at a lower price than the lamp coal. In order to burn it without waste, turaces are constructed with bare set close. It is the lowest-priced coal in the market, bringing, by the cargo, about $6 per ton. Althongh Diabio coal is much used on steamers, it ie not taken on long voyages, the reason for which, it has heen said, is its liability to spontaneous combnstion. This the owners of the mine deny, saying itis no more liable to spontaneous combuetion than is Cumberland coal, which is used extensively on ocean steamers. The Pacific Meil Company have arrangements for supplies of coel at prices less than can be produced here, excepting possibly, the screenings of tbe Mount Dieblo coal, which is not suitable for the use of ocean steamere, An experiment recently made by Allen Wilcox, et his works, No. 21 Front street, ehowed very little difference between the reletive value of Mount Diablo coal and Oregon pine for generating steam to drive a water-lifter. He ascertained that one ton of good screenings, costing $7 per ton, will raise 432,000 gallons thirty-five feet, equal to one and two-third conts for each 1,000 gallons. One cord at $8 per cord, will raise 456,000 gallone thirty-five feet high,at the vate of one end three-fourth cents for eech 1,000 gallons. Reckoning wood at $5 per cord, each 1,000 gallons will cost one cent end one mill, Bellingham Say Coal. Tbe Bellingham Bay coal is used almost exclusively for domestic purposee, although it leaves a large quantity of eshes, and therefore makes considereble dust in the heerth or grate. It is a free-burning brown coal, with slaty cleavege and brillient conchoidalfracture. Any person familiar with it can recognize it at a glance. Tbe mineis on the eastern chore of Bellingham Bay, in Washiugton Territory, and is more favorably located for shipping purposes then auy other on the coaet, being et the very shore of the Bay, where it cen be teken on hoerd vessels et little expense. The property includes 1,641 acres of timberland. There is a good whert at tbe mouth of the pit, where vessels are loaded. The deposits are very extensive. Itis eimilarly to the Seattle coal in quelity, end the latter hes sometimes been sold for Bellingham Bay to persous who had become used to burning it, and desired thet particular kind. Itis a fact that people form at~tachments for certain kinds of coal. Often .more in eccordance with their prejudices than from any good, clear jndgmeut, and they persistin having coel called by that name even at a higher price than they would heye to pay for the seme articlo under @ different name. Some dealers sell Coos Bay, Seattle, Bellingham Bay and Rocky Mountein allfrom the same heap, whicb is very likely to be from Mount Diablo, the very name of which emecks of the evil one, to say nothing of the sulpbur, which purchaeers wonld be snre to smell if they only knew whereit came from. The fact is, the lower etrata of Mount Diablo coal is as free from sul. phur es other coals of better reputation. Tbe Bellingham Bay Company hasbeen unfortunate during the lest four or five years, the mine haying been several times on fire, and also flooded with water. It is now in working ordcr again, .and is sbipping 3,000 tons per montb, with a prospect of speedily increasing the amonnt to 10,000 tons per month. Tbe compeny own their own vessels—tbe ships Lookout and Germania, of abont 1,500 tons carrying capacity eech, and the bark Amethyst, of 500 tons. The stock is mostly owned in San Francisco, Coos Bay Coal. Tbe Eastport Coos Bay coal mine is situated near Coos Bay, Steteof Oregon ;the land belonging to the company (consisting of 1,600 acres) is nearly all nnderlaid by a coal deposit. The distance from the wherfto the mouth of the mine is tbree-fourths of a mile, and the loaded cars descend to the water’s edge over a railroad of easy grade, by force of gravity, end are returned to the mines by mules. The coal is teken from the wherf se received, withont screening. Itiea clear, hlack coal,; with lustrous conchoidal fracture, free from iron pyrites, no trace of sulphur, leaves comperetivaly little ash, and burns without any disagreeable odor. Itis not so easily kindled as Seattle or Bellingham Bay, is less inflammable than Rocky mouutain coal, cakes comewhat in burning, and gives out considerable gas, which is consumed in puffs, withont odor. The coal of the Newport Coos Bay Company is of the seme general character. The cost of the coal delivered in San Francisco was formerly about $7 per ton. The Eastport Company, hy the construction of a tug boat and other facilities, have rednced ecomewhat the expense of reaching market. By aid of the tug they are enabled to cross the ber with less hindrance than formerly, The use of this coal, as well as the Seattle, has been very greatly increased by the suspension of work in the Bellingham Bay mines. Although the cost is less than formerly, the price is higher, being about $12 por ton by the cargo. The Eastport Company sold 20,000 tons last year, lying one month idle, on account of a strike of the workmen. The Directors have declared a regular monthly dividend of one per cent. on the capital stock. Seattle Coal. The Seattle is an excellent quality of lignite, not properly coal. It burns firecly, makes a cheerful fire in a grate, and answers well for cooking purposes, lighting more easily than most other kinds, and can be used where there is less draft than is required for Coos Bay coal. The Seattle mine is seventeen miles from the town of Seattle, Washington Territory. From the mine to the lake is four miles, over which the coal is shipped by narrow-gauge railroad. The coalis conveyed from the mine to vessels lyingin port at Seattle withont emptying the cars until the coal arrives at the vessel’s side. The Company takes out an average of eighty tons per day; employ abont 120 men, two steam tugs, two large barges, one steam engine, 40 horses and 160 two-ton cars. In 1871 15,000 tone were shipped, two-thirds of ;which came toSan Francisco, In 1872 they took out 35,000 tons, of which 25,000 were brought to this port. It brings $12,50 per ton by the cargo. The expenses are about es follows: $3.50 per ton to mine it and putit in ships at Seattle; $5 per ton for freight, leaying a net profit of $4 per ton, or 30 percent. The owners of the stotk are residents 6f San Francisco and New York city. The demand for tbe coel is steadily increesing. If the Company owned ships in which to bring their coel to market, they could sell fora lower price and make more money. Experiments With Coal, Two years ago a series of very carein] experiments were made with various kinds of coal by Chicf Engineer Isherwood, at Mare Island, in order to ascertain the steem-generating power of the coal, the comparetive qnentity of combnstible meterial in each, the rate of combnstion, etc. His official report hes not yet been published, but the following are some of the results escertained. Weselect only those coele which are used toa greet extent in thie market, being the brown coal fiom Australia, Vancouver’s Island end Washington Territory, and the lignite from Oregon, Californie and Wyoming. [No experiments were made with the Seattle coal, for which there is mnch demend here]: ge 2 F 94 cy WE S Ey ee 5 By = a g =) g Ss 8 ie ie s e is] a GI z E ei : 5 Lbs. coal consumed in " is ‘ 4 : 1 10,225 7,486 11,010 9,860 al, . 2 991 2,507 934 1,55 Per cent. of tne coal ae in ashesand clinker, 8,09 12.36 24.52 1248 14.08 16,62 Lbs. of coal consume: fer hour. -» 358 384 426 311 460 4lt Lbs. water vay rod from 1 Ib. of conl. 7,042 5,326 3,905 4,384 3,782 4,535 If a test of this kind were made at the preseut time the resnlt would be more favorable for the Coos Bay and the Diablo coels, tban is given ehove, for the reeson that a better quelity of coel has been obtained by deeper excevatione, From tbis experiment, as well ae by other tests applied, itis evident that certein varieties of coal sold in this market are not properly classified. A greater price is demanded than the escertained quelity of the coel justifies. Experiments have also been made et Mare Island with a view to determine the number of ponnds of coel required as an equivalent for one cord of the best live oak wood obtainable in this market, the resnlt being es follows: Nanaimo, Vancouver Island, B. C.. Bellingham Bay, Washington Terr‘ Seattle, Washington Territory. Rocky Mountain, Utah.. Mount Diablo, California. 4 Coos Bay, Oregon. .ceeeee sees caeeeeeenarensees The present retail prices of coal per tou in this market ere as follows: Sidney; $17; Nanaimo, $16; Bellingham Bay, $15; Mount Diablo, $12; Coos Bay, $15; Rocky Monntain, $16; Seattle $16. The entire amount of coal production and importation during the lest yeer was not far from 500,000 tons, of which 180,000 tons were from Mount Diablo; ebont 115,000 were from Sidney; and 26,000 from Nenaimo, Vancouver Island—a kind of coal used principully in making gas; asmall quantity of Chilean coel was received, amounting to say 3,000 tons, and about 29,000 tons of English Coal. The importations will undonbtedly continue to decrease, until none is received from abroad except as ballast. The home production will in a fewyears fully supply the demend. New discoveries ere being made of deposits within eosy reach of market, end should the quality of the coel prove as good es that already developed the price of coal mnst eventually de~ . creaee,— Bulletin, Professor Agassiz on the Negro. In a recent lecture Agessizremarked: ‘I have pointed out over s hundred specific differen+ ces between the bonal and nervoue systems of the white man and the negro. Indeed, theiy frames are alike in no particnlar. There is no bone in the negro’s body which is relatively the same ehape, size, articulation, or chemicelly of the same composition as thet of the white man, The negro’s bonee contein a fer greater proportion of calcereons salts than those of the white man, yen the negro’s blood is chemically a very different fluid fromi that which courses in the veins of thewhite man. The whole phyeical organization of the negro differs quite as manch from the white man’s as it does from that of the chimpanzee—that is in his bones, muscles, nerves and fibres, the ohimpanzee has not much farther to progress to become a white man. This fact science inexorably demonstratee. ‘* Climate has no more to do witb the difference between the white man and the negro than it hee with that between the negro and the chimpanzee, or it has between the horse and the ase, or the eagle and the owl. Each is a distinct and separate creation. The negro and the white man were created ae specifically different as the owl and the eagle. They were designed to fill different places in the system of natnre, The negro is no more a negro by accident or misfortune than the owl ia the kind of a bird he is by accident or misfortune. The negro is no more the white man’s brother then the owl is the sister of the eagle, or the ase the brother of the horse. How stupendous, and yet how simple, is the doctrine that the Almigbty maker of the nniverse has created different species of men, just ae he has different species of the lower animals, to fill different” places and offices in thegrand machinery of nature,”

82 MINING AND SCIENTIFIC PRESS. {February 8, 1873. (GORRESPONDENCE. Case-Hardening. Written for the Press. It ie a very obvions fact, that a hard-working surface will last very much longer than a oft one, hesides doing away to a very greet extent, with the likelibood of the two surfaces cutting or seizing —thet bugbeer of all engineers. I have seen.the elide-valves and velve-seets of locomotive engines so soft, that face them down ever so true, before they bad run for e month, the seet would be worn en eighth of an inch hollow, and the valve correspondingly round, on tbe surface, thus destroying very meterially the working power of the engine, as it would be impossible in euch a cese for the engine either to receive, cut off, or emit her steam with tbe precision that is reqnired. The valve motion, too, may be closed, all loet motion teken out of pins, pin-holes, ete., but the metel being soft, or merely smeared over with potash, will, before the engine has made many trips, give so much end wear away so quickly, that it looks like a nseless expenditure of labor either to repair or make machinery and send it ont to work in that style. How, then, is it to be avoided ; whet shell be done to remedy the evil ? As far as cast-iron is concerned, of conrse notbing cen bedoue toward meking that herder then if naturelly is; but there is a procese by which wrought iron cen be mede so extremely hard as to equal herdened steel—thet process is case-hardening. I heve been surprised to find thie so mnch neglected both in the Eastern Stetes and on the Pecific Slope. The process is eo simple, and can be done with so little -expense thet, considering tbe immense adventages to be gained, it bas been a wonder to me why there was not a case-bardening furnace put upatall machine shops. I have essisted et casehardening in Europe and also in this country, and for the benefit of mechanics and the trade generally, I will give, in es clear a way as I can, the result of my obeervation and experience, Afurnece shonld be constructed of stone, well cemented together, walls not less than one foot in thickness; the size of furnace, of course, would be mede to suit the qnentity of work each shop hed to do. Iron rods end stays should be worked in with tbe masonry across the furnace on which to lay the box, directly nunderneath being the fire space, the grate of which should stand one foot from the ground, eo as to allow a good draft nnderneeth and elso room for the ashes to fell. If not convenient to build a brickor stone chimney, stovepipe will enswer the purpose. Tbe box ehonld be made large enough to hold the different-sized pieces of metal to be hardened; but it is better to bave two boxes, rather then one too large and nnwieldly to manege; as in thet case troublo is likely to arise in getting the box out of the furnece, it being so extremely hot that it is impossible to handle it except with very long tongs, rekes, ete. The box should be made of % inch sheet iron, well riveted together with angle iron. The meterial used io mixin witb the work consists of bonee bnrned toa chercoal, with leather shevinge, burned or not burned—it does equally as well. Indeed, in some shops neither the bones nor the leather is burned at all; but cnt or mashed up very fine. This is mixed with chercoal end distributed carefully among the work to be hardened. If a piece of metal is of any coneiderablelength, cure should be taken to pack it well, for if it should rest only on its two ends it would surely get sprung in the middle, end vice versa. Ley the work carefully among the prepared stuff—one layer of stuff on the bottom of the box, then as mnch metal as can conveniently be laid down withont letting the pieces touch each other; another layer of chercoal, etc., on the top of that, eeeing that ell the various holeein the workare wellfilled; then more work, and eo on till the box is full. When fastening down the lid, it is ready for the furnace. When the door of the furnace is closed, unless it fits very close, put some fine clay all round so ae to effectually exclude all cold drafts that otherwise pass through the furnace. Some man shonld be detailed to attend to the fnrnace, and keep upa good fire, day and nigbt, so that the box is kept at dull red heat all the time. The time for keeping it in the furnaceis generally twenty-four houre. At the expiration of that time tbe box should be drawn, and cold water having been previously prepared closeby, it being kept cold by a continnous stream from hose or otherwise, the various pieces of work are picked ont and ae expeditiously as possible dropped into the water. Let me say, here, that thongh it shonld be taken from the box as quickly as poseible, to prevent the work from sealing, yet it sbonld he done with the greatest coolnese, I have have eeen men with their pokers and tongs dab into the red hot maes to wrench up from the bottom the pieces that lay there, either through excitement or ignorance, forgetting that ae the work is red hot, the smallest blow will raise a, nasty burr, which may prove tronblesome to get off afterward. A small burr raised on the edge of, or in a hole that has to work, has occasioned the necessity of softening to get it out, as itis impossible to touch work so hardened with a file of eny description. Tf the fnrnece has been ettended to properly the work will now heve a surfece ranging from 1-32 to 1-16 of an inch in thicknees, so hard thet nothing but the grindstone or emery will be eble to effect it, in making the various parts work together freely. A high and durable polish can now be pnt on by rubbing with emery cloth, andif the work has been carefully filed up, while in a soft state, it will look very nice indeed; but if, on the contrery, it has been filed too hastily or too carelessly, and deep scratches left, it will be impossible to polish it up, es the scratch will have widened and got bleck, defying the power of the polisher to make it anytbing else, buta deep, ugly seratch. The filing up work to be hardened, and leaving deep marks and putting on a high polish, to hide them for the time being after they come from the furnace, is very objectionable; it looks detestable to a practical mecbanic. Only wronght iron can be snbjected to this process. Cast iron is simply made more brittle. A master mechanic thet I wes once working for, desired me to put in the box a piece of cast iron to test the effect, stating that he thought if the hardening process wes good for wrought iron, it must he equally good for cast iron. I did es I was desired, end efter ell was cooled off I took the piece of castiron and snapped it in two with my fingers. If crank pins ere required to be hardened, tbe plain part that goes in the wheel should be well wrapped up with cley, so as to prevent as much as possible the absorption of carbon by the metal, and when cooled, they shonld be put in a trongh with water deep enongh to cover the working part, tbe other being mado to stand above the weter. MEcHanic. Carlin, Jannary, 1873. Coal for Domestic Use in San Francisco. What Kinds are Used in San Francisco—Where They Come From—Quantity, Quality, Etc. Nearly all the coal used for domestic pnrposee in California is mined on the Pacific slope. Weet Hartley is used to some extent, bunt most of thet sold by retailers for West Hartley is either mixed or entirely of eome other kind. There isno true coal fonnd west of the Rocky Mountains, with the exception of some veins on Vencouver Island, end possibly in some other portion of British Columbia. Tbe coal veins of California and Washington Territory ere of later geological formation than the enthracite beds of Pennsylvania end other Eastern Stetes. The Pacific coast production is a species of lignite, not properly coel. Anthrecite, sometimes called stone coal, is hard, bleck coel, does not soil the fingers when touched, fracture conchoidal, decrepitates in burning, kindles with difficulty, contains e very large proportion of cerbon, very little oxygen, hydrogen, and nitrogen. Bituminons, or soft coel, varies much in color, weight and quality. Some species heve a luster more waxy then that of anthacite, fracture uneven, often divided by joints into parallels; from 73 to 90 per cent. carbon, end from 8 to 22 per cent. oxygen, hydrogen and nitrogen, with considerable earthy matter and ash, The term ‘‘Bitumen” as epplied to coel does not mean that it contains minerel pitch, bnt that oxygen, hydrogen and nitrogen giveit a more inflammable cheracter. The bituminous coals are divided into sorts eccording to their burning properties, such as “‘free burning,” ‘‘smokeless,” ‘‘non-ceking,” etc. The caking coals are those which tend to partially fuse while burning, emitting smoke and jetsof ges. A single seam of coal sometimes contains layers of various quality. ~ Mount Diablo Coal. The shipments of coal from the Mount Diablo mines are larger than those of any other mine on the coast, amounting to about 180,000 perannum. The coal is used mainly for the generation of steam. It is consumed in steamers, mills, and manufacturing establishments. Some years ago, before the miners had penetrated to any great depth, the coal contained considerable enlphur, which emitted an nnpleasant odor while burning, and injured the repntation of the coal for domestic use. Since the opening of the Black Diamond, Union and Independeut veins, the quality has improved, and although little is openly sold for domestic use, it is often disposed of under other names, and the housewife does not know that she is bnrning that ‘nasty sulphur stuff.’”’ The miners are now working in solid coal, of good quality. Ahont twenty per cent. of this coal reaches the market in the form of screenings, which ie sold at a lower price than the lamp coal. In order to burn it without waste, turaces are constructed with bare set close. It is the lowest-priced coal in the market, bringing, by the cargo, about $6 per ton. Althongh Diabio coal is much used on steamers, it ie not taken on long voyages, the reason

for which, it has heen said, is its liability to spontaneous combnstion. This the owners of the mine deny, saying itis no more liable to spontaneous combuetion than is Cumberland coal, which is used extensively on ocean steamers. The Pacific Meil Company have arrangements for supplies of coel at prices less than can be produced here, excepting possibly, the screenings of tbe Mount Dieblo coal, which is not suitable for the use of ocean steamere, An experiment recently made by Allen Wilcox, et his works, No. 21 Front street, ehowed very little difference between the reletive value of Mount Diablo coal and Oregon pine for generating steam to drive a water-lifter. He ascertained that one ton of good screenings, costing $7 per ton, will raise 432,000 gallons thirty-five feet, equal to one and two-third conts for each 1,000 gallons. One cord at $8 per cord, will raise 456,000 gallone thirty-five feet high,at the vate of one end three-fourth cents for eech 1,000 gallons. Reckoning wood at $5 per cord, each 1,000 gallons will cost one cent end one mill, Bellingham Say Coal. Tbe Bellingham Bay coal is used almost exclusively for domestic purposee, although it leaves a large quantity of eshes, and therefore makes considereble dust in the heerth or grate. It is a free-burning brown coal, with slaty cleavege and brillient conchoidalfracture. Any person familiar with it can recognize it at a glance. Tbe mineis on the eastern chore of Bellingham Bay, in Washiugton Territory, and is more favorably located for shipping purposes then auy other on the coaet, being et the very shore of the Bay, where it cen be teken on hoerd vessels et little expense. The property includes 1,641 acres of timberland. There is a good whert at tbe mouth of the pit, where vessels are loaded. The deposits are very extensive. Itis eimilarly to the Seattle coal in quelity, end the latter hes sometimes been sold for Bellingham Bay to persous who had become used to burning it, and desired thet particular kind. Itis a fact that people form at~tachments for certain kinds of coal. Often .more in eccordance with their prejudices than from any good, clear jndgmeut, and they persistin having coel called by that name even at a higher price than they would heye to pay for the seme articlo under @ different name. Some dealers sell Coos Bay, Seattle, Bellingham Bay and Rocky Mountein allfrom the same heap, whicb is very likely to be from Mount Diablo, the very name of which emecks of the evil one, to say nothing of the sulpbur, which purchaeers wonld be snre to smell if they only knew whereit came from. The fact is, the lower etrata of Mount Diablo coal is as free from sul. phur es other coals of better reputation. Tbe Bellingham Bay Company hasbeen unfortunate during the lest four or five years, the mine haying been several times on fire, and also flooded with water. It is now in working ordcr again, .and is sbipping 3,000 tons per montb, with a prospect of speedily increasing the amonnt to 10,000 tons per month. Tbe compeny own their own vessels—tbe ships Lookout and Germania, of abont 1,500 tons carrying capacity eech, and the bark Amethyst, of 500 tons. The stock is mostly owned in San Francisco, Coos Bay Coal. Tbe Eastport Coos Bay coal mine is situated near Coos Bay, Steteof Oregon ;the land belonging to the company (consisting of 1,600 acres) is nearly all nnderlaid by a coal deposit. The distance from the wherfto the mouth of the mine is tbree-fourths of a mile, and the loaded cars descend to the water’s edge over a railroad of easy grade, by force of gravity, end are returned to the mines by mules. The coal is teken from the wherf se received, withont screening. Itiea clear, hlack coal,; with lustrous conchoidal fracture, free from iron pyrites, no trace of sulphur, leaves comperetivaly little ash, and burns without any disagreeable odor. Itis not so easily kindled as Seattle or Bellingham Bay, is less inflammable than Rocky mouutain coal, cakes comewhat in burning, and gives out considerable gas, which is consumed in puffs, withont odor. The coal of the Newport Coos Bay Company is of the seme general character. The cost of the coal delivered in San Francisco was formerly about $7 per ton. The Eastport Company, hy the construction of a tug boat and other facilities, have rednced ecomewhat the expense of reaching market. By aid of the tug they are enabled to cross the ber with less hindrance than formerly, The use of this coal, as well as the Seattle, has been very greatly increased by the suspension of work in the Bellingham Bay mines. Although the cost is less than formerly, the price is higher, being about $12 por ton by the cargo. The Eastport Company sold 20,000 tons last year, lying one month idle, on account of a strike of the workmen. The Directors have declared a regular monthly dividend of one per cent. on the capital stock. Seattle Coal. The Seattle is an excellent quality of lignite, not properly coal. It burns firecly, makes a cheerful fire in a grate, and answers well for cooking purposes, lighting more easily than most other kinds, and can be used where there is less draft than is required for Coos Bay coal. The Seattle mine is seventeen miles from the town of Seattle, Washington Territory. From the mine to the lake is four miles, over which the coal is shipped by narrow-gauge railroad. The coalis conveyed from the mine to vessels lyingin port at Seattle withont emptying the cars until the coal arrives at the vessel’s side. The Company takes out an average of eighty tons per day; employ abont 120 men, two steam tugs, two large barges, one steam engine, 40 horses and 160 two-ton cars. In 1871 15,000 tone were shipped, two-thirds of ;which came toSan Francisco, In 1872 they took out 35,000 tons, of which 25,000 were brought to this port. It brings $12,50 per ton by the cargo. The expenses are about es follows: $3.50 per ton to mine it and putit in ships at Seattle; $5 per ton for freight, leaying a net profit of $4 per ton, or 30 percent. The owners of the stotk are residents 6f San Francisco and New York city. The demand for tbe coel is steadily increesing. If the Company owned ships in which to bring their coel to market, they could sell fora lower price and make more money. Experiments With Coal, Two years ago a series of very carein] experiments were made with various kinds of coal by Chicf Engineer Isherwood, at Mare Island, in order to ascertain the steem-generating power of the coal, the comparetive qnentity of combnstible meterial in each, the rate of combnstion, etc. His official report hes not yet been published, but the following are some of the results escertained. Weselect only those coele which are used toa greet extent in thie market, being the brown coal fiom Australia, Vancouver’s Island end Washington Territory, and the lignite from Oregon, Californie and Wyoming. [No experiments were made with the Seattle coal, for which there is mnch demend here]: ge 2 F 94 cy WE S Ey ee 5 By = a g =) g Ss 8 ie ie s e is] a GI z E ei : 5 Lbs. coal consumed in " is ‘ 4 : 1 10,225 7,486 11,010 9,860 al, . 2 991 2,507 934 1,55 Per cent. of tne coal ae in ashesand clinker, 8,09 12.36 24.52 1248 14.08 16,62 Lbs. of coal consume: fer hour.. -» 358 384 426 311 460 4lt Lbs. water vay rod from 1 Ib. of conl. 7,042 5,326 3,905 4,384 3,782 4,535 If a test of this kind were made at the preseut time the resnlt would be more favorable for the Coos Bay and the Diablo coels, tban is given ehove, for the reeson that a better quelity of coel has been obtained by deeper excevatione, From tbis experiment, as well ae by other tests applied, itis evident that certein varieties of coal sold in this market are not properly classified. A greater price is demanded than the escertained quelity of the coel justifies. Experiments have also been made et Mare Island with a view to determine the number of ponnds of coel required as an equivalent for one cord of the best live oak wood obtainable in this market, the resnlt being es follows: Nanaimo, Vancouver Island, B. C... Bellingham Bay, Washington Terr‘ Seattle, Washington Territory.. Rocky Mountain, Utah.... Mount Diablo, California.. 4 Coos Bay, Oregon.. .ceeeee sees caeeeeeenarensees The present retail prices of coal per tou in this market ere as follows: Sidney; $17; Nanaimo, $16; Bellingham Bay, $15; Mount Diablo, $12; Coos Bay, $15; Rocky Monntain, $16; Seattle $16. The entire amount of coal production and importation during the lest yeer was not far from 500,000 tons, of which 180,000 tons were from Mount Diablo; ebont 115,000 were from Sidney; and 26,000 from Nenaimo, Vancouver Island—a kind of coal used principully in making gas; asmall quantity of Chilean coel was received, amounting to say 3,000 tons, and about 29,000 tons of English Coal. The importations will undonbtedly continue to decrease, until none is received from abroad except as ballast. The home production will in a fewyears fully supply the demend. New discoveries ere being made of deposits within eosy reach of market, end should the quality of the coel prove as good es that already developed the price of coal mnst eventually de~ . creaee,— Bulletin, Professor Agassiz on the Negro. In a recent lecture Agessizremarked: ‘I have pointed out over s hundred specific differen+ ces between the bonal and nervoue systems of the white man and the negro. Indeed, theiy frames are alike in no particnlar. There is no bone in the negro’s body which is relatively the same ehape, size, articulation, or chemicelly of the same composition as thet of the white man, The negro’s bonee contein a fer greater proportion of calcereons salts than those of the white man, yen the negro’s blood is chemically a very different fluid fromi that which courses in the veins of thewhite man. The whole phyeical organization of the negro differs quite as manch from the white man’s as it does from that of the chimpanzee—that is in his bones, muscles, nerves and fibres, the ohimpanzee has not much farther to progress to become a white man. This fact science inexorably demonstratee. ‘* Climate has no more to do witb the difference between the white man and the negro than it hee with that between the negro and the chimpanzee, or it has between the horse and the ase, or the eagle and the owl. Each is a distinct and separate creation. The negro and the white man were created ae specifically different as the owl and the eagle. They were designed to fill different places in the system of natnre, The negro is no more a negro by accident or misfortune than the owl ia the kind of a bird he is by accident or misfortune. The negro is no more the white man’s brother then the owl is the sister of the eagle, or the ase the brother of the horse. How stupendous, and yet how simple, is the doctrine that the Almigbty maker of the nniverse has created different species of men, just ae he has different species of the lower animals, to fill different” places and offices in thegrand machinery of nature,”