200 ANNUAL OF SCIENTIFIC DISCOVERY. 



ON THE PRODUCTION OF ARTIFICIAL MINERAL COAL. 



AN interesting communication was recently presented to the French 

 Academy, by M. Cagniard Latour, relative to the production of arti- 

 ficial mineral coal. It is known that Sir James Hall, putting fir, saw- 

 dust, and horn into a gun-barrel, and subjecting them to heat, suc- 

 ceeded in melting this compound and converting it into a sort of coal. 

 These experiments have recently been renewed by the gentleman above 

 named, under different conditions and with better success. Instead of 

 gun-barrels he used glass tubes, 14 centimetres (five and five eighths 

 inches) in length and three millimetres (0.11811 inch) in diameter. 

 The glass should be two or three millimetres thick. These dimensions 

 were found, upon trial, to be the best adapted to enable the common 



flass tubes to support the degree of heat to \vhich they were subjected. 

 I. Cagniard Latour dispensed with horn and all other agents to facili- 

 tate fusion ; and he operated not only upon fir, but upon a great variety 

 of other woods birch, poplar, sycamore, elm, oak, boxwood, lignum- 

 vitse. It is remarkable that the degree of heat used in these experi- 

 ments was not superior to, indeed was hardly equal to, that of boiling 

 mercury (660.) The bits of wood were put in the tube, which was 

 hermetically closed at both ends, and then placed in a spiral cylinder 

 of iron wire, for the purpose of being conveniently held over a pan of 

 burning charcoal. If, by this process, the heating seemed tedious, the 

 tubes were plunged into boiling mercury. The result of the experi- 

 ments was an artificial coal, varying in character, according to the age 

 and hygrometric state of the woods employed. The wood of young 

 trees was converted into a glutinous coal ; the old wood, of dry fibre, 

 into a dry coal. But these last, if soaked in water before being placed 

 in the tube, gave a glutinous coal like the young wood ; and, in some 

 instances, a brown resin, very similar to asphaltum. The woods used 

 in these experiments had been, by way of preparation, dried by a heat 

 of 100. " May it not be hoped," says the experimenter, in the con- 

 clusion of his communication, " that essays of this kind, suitably multi- 

 plied and varied, will lead to results of which geology may make most 

 useful and important application ? ' 



ON THE VALUE OF VARIOUS KINDS OF COAL FOR STEAM PURPOSES. 



FROM the third report of the Commission appointed to examine and 

 report upon the coals of Great Britain, as regards their applicability 

 for naval steamers, we make the following extract. The commission 

 consisted of Sir H. de la Beche and Dr. Lyoii Playfair. 



" Although the analysis of a coal shows, generally, that the quan- 

 tities of carbon and hydrogen it contains materially regulate its 

 economic value, still there are marked exceptions to this rule, showing 

 that in all inquiries as to the real value of coal for fuel, its economic 

 value as to its evaporative power, by actual trial under the boiler, 

 should be ascertained. The coals, for instance, of the Newcastle dis- 

 trict, are, in general, of very different composition from the Welsh coals. 

 They are characterized by containing a smaller quantity of carbon, but 



