520 



SCIENCE. 



[Vol. I., No. 18. 



mated at two francs per 100 kilos of poor-quality 

 iron. — (Iron, April 6; Eng. min. journ., March 

 31. ) R. H. R. [1023 



The working of blast-furnaces. — At a meet- 

 ing of tlie Society of meclianical engineers, Jan. 2.5, 

 Mr. Cliarles Cochrane read an elaborate paper on the 

 working of blast-furnaces with special reference to 

 the conditions under which the analysis of the escap- 

 ing gases is of value. The object of the author is to 

 establish the fact that all economy in fuel, consumed 

 to make a ton of pig iron with any particular class 

 or size of furnace, is governed by three conditions : 

 1. Temperature of air introduced ; 2. Temperature 

 of escaping gases ; .3. The quantity of carbon which 

 can be maintained in the condition of carbonic-acid 

 gas after it has once been transformed to this degree 

 of oxidation from the carbonic oxide produced in the 

 hearth. The paper contains tables calculated for 

 conditions varying from good to bad. Several illus- 

 trations of furnace- working are given, of which the 

 No. 3 Ormsby furnace is one. The ratio of car- 

 bonic acid to carbonic oxide was 424. The tem- 

 perature of the blast was 700° C. ; of the escaping 

 gases, 340° C. Carbon as coke, per ton of pig, was 

 21.98 cwt. ; carbon in limestone flux, per ton of pig, 

 was 1..50 cwt. By the tables it is shown, that, without 

 the weight of carbon as a factor, there are six con- 

 ditions of furnace-working indicated by the analysis of 

 the gases ; but, taking the carbon also into account, 

 it is shown that the ideal furnace should have used 

 but 16 cwt. of carbon per ton of pig : hence 5.98 cwt. 

 of carbon have been reduced from carbonic acid to 

 carbonic oxide. — {Iron, Feb. 2.) B. H. K. [1024 



The Carvds coking system. — The ovens are 

 long, high, narrow chambers of brick-work built side 

 by side. The partition-walls contain horizontal flues 

 as well as the floor of the ovens. No air is allowed 

 to enter; and the only opening left during the heating 

 is the pipe which carries the volatile products through 

 condensation and absorption apparatus in order to 

 save the tar and ammonia-water. The gas is con- 

 ducted by the floor-flues to the small fire-grate at one 

 end of the oven, and there burned ; the products of 

 combustion pass through the wall-flues, on their way 

 to the stack; and, by this means, much heat is saved. 

 There is no burning and consequent loss of the coal it- 

 self, as is the case in the beehive ovens ; also the val- 

 uable by-products are saved. Tests show that the 

 hardness of the coke increases as the width of the 

 oven decreases. The cause of this is probably due to 

 the quick and intense heating. The fixed carbon 

 obtained in this way is about 75 per cent, while other 

 methods give only ,55 to 65 per cent. A battery of 

 one hundred ovens will furnish steam for about 400 

 horse-power over and above the making of the coke 

 and the rendering of the products. — (Coal, March 

 28. ) R. H. R. [1025 



Artificial fuel. — The process of Mr. E. F, Loiseau 

 for making artificial fuel from coal-dust is in success- 

 ful operation in Philadelphia, where from 80 to 300 

 tons, according to size of the lumps, are made daily. 



The process of manufacture may be briefly outlined 

 as follows: — 



The coal-dust is fed into hoppers, together with 

 about eight per cent of bituminous slack, from which 

 it passes through a series of four cylindrical revolv- 

 ing drums, in which it is thoroughly dried. From 

 these it is carried to a receptacle situated near the 

 press. The dust, still at a temperature of about 140° 

 F., is then thrown into the mixing apparatus, in 

 which it is thoroughly stirred by revolving shafts 

 with blades, while the proper quantity of pitch and 



coal-tar is added from a reservoir in which it is main- 

 tained at a temperature of 180° by steam-heat. The 

 pitch is mixed with a certain quantity of coal-tar 

 to give it the proper toughness. When thoroughly 

 mixed with the melted pitch, the mass is plastic, and 

 can readily be moulded into any desired shape. It is 

 then carried to the press, where it is delivered between 

 rolls having moulds upon their surfaces, from which 

 the egg-shaped lumps are discharged. When dis- 

 charged from the press, the lumps are quite hot, and 

 have to be cooled by jets of water. 



As thus prepared, the fuel is compact and very hard. 

 Formerly clay was used as a cementing material, but 

 now no incombustible or ash-producing material is 

 required. The fuel is said to be even superior to the 

 natural coal; and this opinion is borne out by an 

 analysis which gave the following results: — 



Chestnut anthracite. Loiseau fuel* 



Cavbon 73.40 82.01 



Hydrogen 3.09 2.56 



Moisture 0.44 2.41 



Ash 17.95 10.47 



Nitrogen and oxygen by differ- 

 ence 5.12 2.55 



Theoretical calorific power, 



British thermal units . . 12,339.50 13,853.00 



Equivalent to the evaporation, 

 from and at 212°, of lbs. 



water 12.76 lbs. 14.33 lbs. 



[1026 



AGBICULTUBE. 

 Earth-viromis and fertility. — According to Hen- 

 sen, earth-worms increase the fertility of the soil by 

 forming burrows through which the roots of plants 

 can descend into the subsoil. This applies chiefly to 

 Lumbricus terrestris, while L. communis is confined 

 chiefly or entirely to the surface-soil. The tap-roots 

 of many plants, he thinks, may be able to force their 

 own way through the hard subsoil ; but the more 

 slender side-roots descend chiefly through worm-bur- 

 rows, or other channels, such as those left by old 

 decayed roots. By excavating in frozen ground, he 

 was able to trace roots downward through worm-bur- 

 rows, and to observe that the layer of excrements 

 with which the latter were lined was covered with a 

 delicate network of root-hairs proceeding from the 

 root in the interior. An important function of these 

 roots Hensen believes to be, to supply the plant with 

 water from the moist subsoil; and this is particularly 

 important in the case of quick-growing annuals, like 

 the cereals, which must develop their root-system 

 rapidly, and frequently have to withstand prolonged 

 dry weather. It is plain that no new material 

 can be added to the soil by earth-worms ; but they 

 effect the fixation of vegetable matters in the soil 

 by drawing into their burrows leaves, and other 

 loose fragments of vegetation: they hasten their 

 decomposition, and distribute them through the 

 various layers of the soil. — (Landw.jahrb., xi. 661.) 

 H. P. A. [1027 



GEOLOGY. 



Lithology. 

 The Ardennes phyllites. — Extended chemical 

 and microscopic examinations of the Ardennes phyl- 

 lites by Renard show that they are composed of seri- 

 cite, ciiloritoid, and either quartz or calcedony, with 

 variable quantities of magnetite, hematite, pyrite, 

 pyrrhotite, ottrelite, sillimanite, rutile, tourmaline, 

 zircon, garnet, and carbonaceous material. Apatite 

 was observed in one specimen. — (Bull. mus. roy. 

 Belg., i.) m. e. w. [1028 



