270 



THE CIVIL ENGINEER AND ARCHITECT'S JOURNAL. 



QSeptember, 



of the Aflmiralty, to ascertain how far mixtures of anthracite with 

 more l)ituiiiiiii>us coals were likely to prove advantageous in the 

 manufacture of artificial fuel. The apparatus used in the manu- 

 facture of the contract fuel for Her Alajesty's dockyard, under tlie 

 patent of Mr. ^^'^arlich, havinir been placed at our disposal, various 

 mixtures were made and tried under the boiler. It was, however, 

 ascertained, that the advantages of these additions were not such 

 as to recommend their adoption. The cementing- tar, tliough par- 

 tially carbonised by the heat of the coking ovens in which the pre- 

 pared fuels are heated, was so much more combustible than tlie 

 dense and difficultly burning anthracite, that the latter remained 

 after the combustion of the former, and it therefore either ac- 

 cumulated on the bars in the state of powder, obstructing the 

 draught, or, falling through the gi-ate, escaped combustion. If 

 thrown again on the fire, it choked the air-way, and impeded the 

 proper action of the fuel. The evaporative power of the fuels 

 thus prepared, was certainly found to increase according as the 

 proportion of fixed carbon was augmented; but this would appear 

 to arise from the fuel then assuming more of the characters of 

 the anthracite, or coke, from which it was made. The results of 

 the experiments pointed to the necessity of keeping an uniform 

 character in the fuel manufactured. 



VV'ith these observations we would draw attention to the follow- 

 ing abstract of the coals examined: — 



Table I. — Showing the Economic Values of the Coals. 



The annexed abstract of the working tables will give a general 

 view of the relative value of the coals experimented upon. A 

 coal, for example, may appear by this table to possess a high 

 evaporative power, and yet it may burn so sluggishly, and require 



so much attention from the stoker to procure its maximum result, 

 that the mere inspection of its evaporative value would give it a 

 higher rank than that to which it is entitled. It is impossible, 

 however, in an abstract to detail all the special characteristics of 

 a coal, and therefore such a table only gives a certain amount of 

 information, and does not render unnecessary a detailed descrip- 

 tion. 



Table II. 

 Mean Composition of Average Samples of the Coals. 



Tadi.e III. 

 Calorific Values, 



With regard to the manner in which the fuels included in the 

 annexed tables were selected, for examination, the same plan was 

 followed as that adopted prior to the former Report. Careful in- 

 quiries were made at the different ports in the neighboui'hood of 

 tlie coal-fields, as to the kind of coal exported for steam purposes; 

 information from steam-shin companies, in the habit of using the 

 coals of that district was collected, and the local character of the 

 fuel was ascertained. Circulars were then forwarded to the owners 

 of such coals, explaining the object of the inquiry, and requesting 

 them to furnish two tons for experiment. In most instances these 

 were immediately responded to, and the requisite quantity was 

 sent; in a few cases tlie owners did not furnish the supply neces- 

 sary. It was not consistent with our instructions to make pur- 

 chases, as it is usual that the coal experimented on should be 

 delivered free of charge. It is, therefore, possible, that in the 

 coal-fields examined, excellent varieties of fuel may not be in- 

 cluded in our list, and tliis may have arisen either from the cir- 

 cumstance of the owners not responding to our request, or from 



