87 



COAL TRADE. 



COBALT. 



The coals brought to London by sea are mostly in collier sailing- 

 brigs. The competition in the trade, however, has in late years led to 

 a new mode of transport, by screw steam-vessels. From a paper read 

 before the Institution of Civil Engineers in 1854, it appears that, about 

 that date, the screw-colliers in use carried about double the average 

 cargoes of sailing-colliers, and were capable of making thrice as many 

 voyages in a year. An average screw-collier, therefore, did six times 

 as much work as a sailing-collier. A sailing-collier, carrying 300 tons, 

 and making ten voyages in a year, might be bought for 1200?. to 1800?.; 

 and six of them would about equal in cost one screw-collier, carrying 

 600 tons, and costing 10,000?. Then, on comparing all expenses attend- 

 ing the carrying of 18,000 tons of coal to London, those of the screw- 

 collier amounted to 5050?., while those of the six sailing-colliers 

 amounted to 6420?. The sunk capital being about equal in the two 

 cases, and the working expenses exhibiting the ratio here mentioned, 

 the difference amounted to Is. 6<?. per ton, or 20 per cent., in favour of 

 the screw-collier. Sailing-colliers, worked on the most approved prin- 

 ciples, could bring coals from the Tyne to London at 5s. Sd. per ton ; 

 whereas screw-colliers could do the same work for 3s. 6d, the same 

 rates being taken for both in relation to wages, provisions, and stores. 

 It was argued, in the discussion which followed the reading of the 

 paper here adverted to, that screw-colliers are indispensable to the 

 serving of a steady and efficient supply of sea-borne coal to London, 

 combined with good collier-docks at both ends of the route (such as 

 the admirable Victoria Dock at North Woolwich). Vast fleets of 

 sailing-colliers are sometimes detained in the Tyne by adverse winds, 

 or by want of water on the bar ; then, on a change of weather, they all 

 set sail together, and arrive at the Thames in a very cloud of sail, where 

 perhaps they have to beat up a hundred miles of river against wind and 

 tide. Hence the variation of supply, followed by variation of price. 

 The cure for this would be a powerful fleet of screw-colliers, constantly 

 and punctually running, with commodious docks at both ends of the 

 route, and all the best modern facilities for rapid discharge by steam- 

 cranes instead of coal-whipping. Experience, however, has not alto- 

 gether confirmed the anticipations of the steam-collier projectors. 

 The sailing-colliers, it is found, can yet do the work more cheaply on 

 the whole. 



The question has been much discussed, whether the use of screw- 

 colliers would realise one of the objects sought to be attained by 

 vastness of size in reference to the ship Leviathan, or Great Eastern. 

 Ordinary steamers, going to the Cape, to India, or to Australia, are 

 obliged to stop on the way to take in coals ; and as native coal is not 

 found on the coaling stations, a supply has to be taken from England. 

 This supply is conveyed by sailing-colliers, and the price of coal hence 

 becomes enormous at the more distant stations. To obviate this evil, 

 the projectors of the Great Eastern planned a ship so large that it can 

 carry a supply of coal sufficient for a voyage to Australia and back. 

 The question now is, whether the capital expended in building the 

 coal-storing part of this enormous ship would not be better applied in 

 building and working a certain number of screw-colliers, making seven 

 or eight knots an hour. Some engineers contend that, at the average 

 rate of freights, wages, and provisions, screw-colliers must be more 

 profitable than the use of an immense ship, in which the coal occupies 

 useful space which could otherwise be available for cargo. The 

 approaching completion of the Great Eastern (August, 1859) will doubt- 

 less prepare the way for the collection of valuable information on this 

 important question. 



Since 1854 the use of screw-colliers has been adopted, not only 

 on the Tyne and Thames route, but in other directions. In 1857 

 one was built to carry coals from Cardiff to London ; it could take 

 1500 tons, exclusive of 150 tons to use as fuel. The hull was of iron, 

 and there were arrangements for carrying 400 tons of water-ballast in 

 the bottom, which could be readily pumped out when the ship arrived 

 back at Cardiff. The ship cost 23,000?., and the intention and hope of 

 its owners were, that it would enable them to underbid the South 

 Wales and Great Western railways in bringing Cardiff coals to London. 



Concerning the actual cost at which coals can be placed on a railway 

 from pits not far distant, an interesting calculation was made early in 

 1869 relating to some collieries in the Forest of Dean. It was esti- 

 mated that of 250 tons placed on the Great Western Railway, 95 tons 

 of block coal could be delivered there at 8. per ton, 70 tons of rubble 

 coal at 6s Sd., and 85 tons of lime-coal at 2., being 69?. 5s. in all. 

 The total cost was 45?. 6s. 3c?., or 3s. 7d. per ton, thus made up : 



s. d. 

 . . . .to per ton 



Cutting the coal in the mine . . . . 

 Loading and rolling to pit's bottom 

 Pit-work, with timber and stone . i . 

 Tram-plates and iron-work . * 

 Rope, tar, oil, and engine expenses . . 

 Breaking and hitching .... 

 Royalty or Rent to the Crown . 



Management 



Conveyance on tram to Great Western Railway , 

 Loading in railway trucks .... 

 Wear and tear of trams and machinery . . 

 Incidental expences 



1 



3 



2 



1 



2 



2 



1 



4 



2 



Oj 



1 



3 7J 



The cost to the consumer, beyond the price of 8s. per ton for block 

 coal, would depend on the railway charges and the dealers' profits. 



One or two other interesting matters concerning the coal trade of 

 the metropolis may here be mentioned. Between the years 1807 and 

 1831 the corporation of London were owners of a Coal Exchange, kept 

 up for their own profit ; but in the last-named year an Act of Parlia- 

 ment converted the Coal Exchange into an open coal market, to be 

 governed on certain regulations. The same Act defined the privileges 

 of the corporation in certain matters relating to the coal trade ; and 

 most of these privileges were further sanctioned by subsequent statutes. 

 A new Coal Exchange was built in 1849, under arrangements very con- 

 venient for sellers, buyers, and factors. The " whipping " of coals in 

 a strange part of "the coal-trade. The coal-whippers are labouring 

 men, who " whip " or transfer the coals from the collier-brigs to barges, 

 which barges generally carry them to wharves at the river side. The 

 work is simply shovelling and hauling; but the men, several years ago, 

 fell into the hands of publicans and others, who acted as middlemen, 

 contracting with a captain or coal-owner to whip a ship of coals at a 

 certain price, and theu employing the men at a smaller price. By a 

 kind of tally system, the men were drawn in to spend nearly all their 

 earnings at shops belonging to the middlemen, for inferior goods sup- 

 plied at high prices. The legislature has attempted to remedy this 

 evil, but without much success ; for if the men are not free agents in 

 their dealings, the law cannot make them so. In 1851 Messrs. Prior 

 introduced a mode of whipping coals by steam-power, and such will 

 probably be the general mode after a time ; but hitherto the hand 

 method has prevailed. 



COBALT (Co). One of the metallic elements. It does not occur 

 naturally in the free state, but usually combined with arsenic, forming 

 arsenide of cobalt (Co As). In mineralogy this ore is known under the 

 names of speiss cobalt, tin-whits cobalt, or stnaltine. Cobalt is also not 

 unfrequently found as cobalt-glance, or bright white cobalt, a combina- 

 tion of arsenide and sulphide of the metal (CoS,, CoAs). Other ores 

 of cobalt have already been described, and their composition detailed. 

 [COBALT, NAT. HIST. Div.] 



Metallic cobalt may, by somewhat tedious processes, be obtained 

 from its ores. On account of the difficulties attending its reduction 

 its properties have not been very thoroughly investigated, and con- 

 sequently it has not yet received any application in the arts. For 

 experimental purposes it may be prepared from the oxalate. The 

 latter placed in a porcelain crucible, enclosed in a very refractory 

 earthen one, and heated in a powerful wind furnace, will usually yield 

 a button of the pure metal. 



Cobalt is hard, brittle, and almost as infusible as iron. Its colour is 

 reddish grey ; it is magnetic, and has a specific gravity of about 8'9. It 

 is soluble in dilute sulphuric or hydrochloric acids, with evolution of 

 hydrogen. It tarnishes when exposed to the air, and is rapidly 

 oxidised by nitric acid. 



Equivalent of cobalt, 29'5. 



The compounds of cobalt are remarkable for the beauty of their 

 colour, and on this account have been used from the time of the 

 ancient Greeks to the present day. 



Zaffre is the name given to the compound of cobalt that occurs in 

 commerce. It is a very impure oxide of the metal, and is produced by 

 roasting the crushed selected ore on the sole of a reverberatory furnace, 

 the sulphur burns to sulphurous acid, and passes off as gas, while the 

 arsenic, oxidised to arsenious acid, is volatilised, and condenses in the 

 long horizontal flues. The ore is finally ground to fine powder with 

 two or three parts of pure siliceous sand. The product thus obtained 

 is largely used in the manufacture of stained glass, principally to give 

 the well known rich blue colour ; it is also extensively employed in 

 the ornamenting of pottery ware. 



Smalt is a very finely ground deep blue glass, manufactured chiefly 

 in Saxony. For this purpose the cobalt ore is only partially roasted, 

 the object being to oxidise the cobalt only ; the product is then 

 mixed with about an equal quantity of carbonate of potash and twice its 

 weight of well ground calcined quartz, and the whole melted together 

 in suitable pots by the heat of a powerful furnace. In a few hours 

 the silica of the quartz, and the potash combine to form a liquid 

 mass of silicate of potash in which the oxide of cobalt dissolves, while 

 the sulphides and arsenides of nickel, bismuth, and other metals, sink 

 to the bottom of the vessel, there fuse, and under the name of speiss, 

 are afterwards made use of as a source of the metal nickel [NICKEL]. 

 The clear blue glass, after being skimmed, is ladled out of the pots and 

 poured into water, by which it is so suddenly cooled that it instantly 

 splits up into innumerable fragments ; it is further minutely divided 

 by grinding with granite stones under water, and the particles sepa- 

 rated into different degrees of fineness by elutriation. Smalt is prin- 

 cipally used as a pigment by paper-stainers. 



Cobalt and can/yen form two well-marked oxides, the protoxide 

 (CoO) and the scso.tuo.ride (Co a 3 ). Some unimportant intermediate 

 oxides also exist. 



Protoxide of cobalt (CoO), eq. 37'5. As this oxide is an important 

 article of commerce, being used to a considerable extent for enamel 

 painting, it is prepared on the large scale from zaffre. The zaffre is 

 dissolved in nitric acid, the solution evaporated nearly to dryness, 

 strained from.the arsenious acid that deposits, diluted with water, and a 

 current of sulphuretted hydrogen passed through the solution till the 



