December 25, 1873. ] 



JOURNAL OP HORTICULTURE AND COTTAGE GARDENER. 



503 



HEATING— FUEL. 



^,i%^=^'NTICIPATING that some of your many 

 readers and correspondents would liave 

 favom-cd us with their experience of heat- 

 ing greenhouses by hot water, gas instead 

 of coal or coke being used as fuel, I have 

 defeiTed reverting to this subject, which it 

 was my intention to have done at an earUer 

 date. As there has been no response to my 

 inqumes in vol. xxiv., page 2.37, I have con- 

 cluded that no one has thought the subject 

 of such importance as to keep an account of the expense 

 of heating garden structiu'es by gas. The comparative 

 value as fuel of coal, coke, and gas cannot be accurately 

 ascertained without statistics such as these, and only an 

 approximation to the truth can be arrived at. Permit me, 

 however, to repeat the queries — viz., 1st, How many cubic 

 feet of gas are abstracted from a ton of coal, its value 

 per thousand feet, and the gallons of water heated by a 

 thousand feet to a temperatui-e of '212' ; or given the size 

 of the house, feet of piping, and feet of gas, what is the 

 cost of keeping it at a certain temperatm-e ? 2nd, The 

 coke produced from a ton of coal after the gas has been 

 taken from it ? 



It is a common idea, and not, I think, an altogether 

 eiToneous one, that of fuel in ordinary use coke gives oil 

 the most heat. This we should not expect to be the case, 

 as before we have coke the gas from the coal is extracted. 

 Now, it might be reasonably expected that coal would give 

 us the heat of the coke, and that of the gas taken from the 

 coal from which the coke was made. This is, however, 

 altogether erroneous, as will be shown by the following 

 table of the heating power of various combustible sub- 

 stances " exhibiting the utmost quantity of water eva- 

 porated by the given weights, and the quantity of ah' 

 capable of producing total combustion." 



Combastible. 



Pounds of 



water which 



a pound can 



heat from 0' 



to 212^ 



Founds of Weight of 

 boiling water atmospheric 

 evaporated, air at 42" to 

 bum 1 lb. 



Perfectly dry wood 



Wood in its ordinary state . 



Wood charcoal 



Pit coal 



Coke 



Tarf 



Turf charcoal 



Carhuretted hydrogen . . . . 



Oil ) 



Wax r 



Tallow I 



Alcohol of the shops 



Specific gravity 0.838 



35.00 

 26.00 

 73.00 

 60.00 

 65.00 

 30.00 

 64.00 

 76.00 



78.00 



52.60 



6.36 

 4.72 

 13.27 

 10.90 

 11.81 

 5.45 

 11.63 

 13.81 



14.18 



9.5G 



5.0G 

 4.47 



11.40 

 9.20 



11.40 

 4.60 

 9.86 



14.58 



1.5.00 

 11.00 



According to the preceding table gas stands second in 

 heating power, being only surpassed by oil, wax, and tallow, 

 which we may leave out, and then gas takes the first 

 place, followed by charcoal, then coke, turf or peat char- 

 coal fourth, and coal fifth. Let us see what this means 



No. eU.—Yuu XS7., New Seriei. 



in heating gallons of water (weight 10 Ibs.l. Then- heat- 

 ing values would appear as follows : — Gas, 7C.U01bs.= 7.60 

 gallons; wood charcoal, 73,00 lbs. =7.30 gallons; coke, 

 Go,001bs. = 6.C0 gallons; turf charcoal, 04,00 lbs. = 6.40 

 gallons; coal, 60.00 lbs. = 6.00 gallons. Coal, therefore, 

 with its gases unextracted stands lowest of tlie five in 

 heating power, and if we include oil, wax, and tallow, 

 sixth. Its maximum heating power is nearly half a 

 gallon less than turf charcoal, less by half a gallon than 

 that of coke, less by a gallon and a quarter than that of 

 wood charcoal, and less by a gallon and a half than gas. 

 This difference may not seem great, but it will be 

 greater than at first sight appears if we represent it by 

 feet of piping, say 2-inch, heated. Coal with 6 gallons is 

 represented by 4.5 feet ; turf charcoal, OArgallons =47 feet; 

 coke, G\ gallons =48 feet 9 inches ; wood charcoal, 7^- gal- 

 lons = 54 feet 4^ inches ; and gas, 7i gallons = 56 feet 

 8 inches. The heating power of gas may, therefore, be 

 safely considered to be the highest of all ordinary com- 

 bustible substances ; wood charcoal is from the limited 

 supply of wood this country affords not pm-ehasable at 

 a price calculated to lead to its adoption, coke must con- 

 sequently take second place ; turf charcoal, inasmuch as 

 it excels coal in heating power, the third rank ; and coal 

 lowest of all, except wood, which may give an average 

 heating power equal to that of tiu-f — viz., 30.00 lbs.= 3 gal- 

 lons, or 22h feet of 2-inoh pipe. 



Turf and wood can never, from their low heating 

 power, compete with coal, or its products coke and 

 gas, unless they are converted into charcoal, and then 

 the heating power of wood charcoal far surpasses that 

 of coke, whilst that of tm-f charcoal considerably exceeds 

 coal. Is it not worth while in these days of dear coal to 

 draw attention to the many thousands of acres of tm-f 

 in the country, and what a boon to the public, as well as 

 a source of wealth to the proprietors, it would bo were 

 the turf made into charcoal, and consequently fuel of 

 high heating power ? As it is, turf is of no use to the 

 country or its owners beyond affording pasturage for a 

 few sheep and herbage for grouse. Railways would be 

 needed to convey the fuel to our towns, they would bring 

 lime and other requh-ements of agriculture, the land would 

 be improved by the removal of the turf, and enough of the 

 charcoal could be left on the ground to render it fertile 

 when assisted with the other substances that would be 

 brought by the scientific agi-iculturist. The exodus of our 

 very sinews — our agricultural brethren— would not be to 

 Canada, but to our moors ; the manufacture of the charcoal 

 would give a profit that would meet the cost of draining, 

 making roads and homesteads, as well as pay a good per- 

 centage on capital, and whilst adding materially to the 

 extent of our food-producing laud would bring down tho 

 price of coal. This would be another stride in continuing, 

 if not increasing, our manufacturing superiority, to which 

 it will not be disputed om- present unparalleled prosperity 

 is mainly due. However, tho iutrocluclion of turf char- 

 coal or other descriptions of fuel may affect the consump- 

 tion of coal, it is certam that this will not for many years, 

 if ever, be superseded. Coal, and its products gas and 



No. 1317.— Vol. L., OU) Sebiis. 



