Coal, smoke, and sewage, scientifically and practically considered : with suggestions for the sanitary improvement of the drainage of towns, and the beneficial application of the sewage : being the substance of a paper read before the Literary and Philosophical Society of Manchester / by Peter Spence.

Spence, Peter

Date:: 1857

Credit: Coal, smoke, and sewage, scientifically and practically considered : with suggestions for the sanitary improvement of the drainage of towns, and the beneficial application of the sewage : being the substance of a paper read before the Literary and Philosophical Society of Manchester / by Peter Spence. Source: Wellcome Collection.

Provider: This material has been provided by The University of Glasgow Library. The original may be consulted at The University of Glasgow Library.

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in justice to the theoretical calculation, add this to the amount that ought to be evaporated. But 100 degrees Fahr. upon 11841bs. is a little more than equal to the evaporation of 100 lbs. of water. This, then, brings the quantity theoretically evaporable to 1285 lbs. of water, by perfect combustion of 100 lbs. of coal, provided all the heat is so applied. But here a deduction must be made: by the Table No. 2, it will be seen th&t the combustion of these constituents of the coal will require 255'81bs. of oxygen. To aflford this weight of oxygen, it will be necessaiy to pass through the furnace il48' lbs. of atmo- spheric air. Now, taking the air at 60 degrees when it enters the fire, and the resulting gases after combustion being nearly the same in volume, at 260 Fahr., we have thus to calculate a loss of 200 degi'ees of sensible heat on aU this weight of gases passed into the chimney. To arrive at anything like accuracy as to this loss, we must take into account the specific heat of these gases; and as the nitrogen of the air forms the largest portion of the gases, we may be satisfied vdth the specific heat of that body, which does not materially difier from the others,- and is the same as air. The specific heat of air, as compared with water, is as 26 to J. To find, then, what heat is lost by the gases, or what amount of water that heat would evaporate, we must multiply the 1148 lbs. of air by -26, which will shew that the heat lost by the gases passing into thfe chimney at 260 Fahr. would heat 298 lbs. of water 200 degrees, or is equal to the evaporation of 60 lbs. of water at ] 60 Fahr. This 60lbs. of evaporation has then to be deducted from the theo- retical quantity of 1285 lbs. before we get to the attainable evaporation. Suppose we also deduct 251bs. for radiation from furnace doors and into the ash-pit, and for heat communicated through the brick work, we arrive at 1200 lbs. of water at 160 Fahr. as the quantity of water which would be evaporated by perfect combustion of 1 OOlbs. of Lancashire coal. After making' all these deductions, it may still be considered that something is due to the impossibility of arriving at perfect theoretical results in actual practice; but this I leave to the consumers of coal, again reminding them that sound theory has fixed the limit of what can be attained ; and until they reach that, their practice is imperfect. Ml-. John Graham, calico printer, favoured the chemical Kection of

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