Although some difference of opinion may exist, as to the extent of the evil, in a medical point of view, we must all concur in agreeing upon the necessity of some plan by which it may be diminished; we shall, therefore, proceed to offer some remarks upon the proposals which have been made, at different times, for obtaining so desirable an object.
Mr. Evelyn’s plan consisted in the removal of all smoking manufactories from London, “five or six miles down the river Thames, or at least, so far as to stand behind that promontory jutting out and securing Greenwich from the pestilential air of Plumstead marshes.” He then proposes gardens and plantations in and about the metropolis, and enumerates a variety of fragrant plants, suited to our climate, and calculated to sweeten and improve the air.[[545]]
In the year 1682, Mr. Justell communicated to the Royal Society, “An account of an Engine that consumes smoke, shewn lately at St. Germains Fair in Paris.” Dr. Leutmann, of Wirtemburgh, described in his “Vulcanus Famulans,” a stove which draws downwards, so that the contrivances of the Marquis de Chabannes, and others who have burnt their smoke by a downward draught of air were not original. Dr. Franklin in 1785 (Memoirs of the Life and Writings of Benjamin Franklin, vol. iv. p. 408) suggested a mode of burning smoke; but to the illustrious Mr. Watt, we are more particularly indebted for the first important hints upon this subject; his patent may be seen in the fourth volume of the Repertory of Arts for 1796, p. 226; and the great engines at the Soho manufactory have all along been worked without smoke; it is therefore not a little extraordinary, as a late reviewer has justly observed, that in the Report from the Committee of the House of Commons “to enquire how far it may be practicable to compel persons using steam engines and furnaces in their different works to erect them in a manner less prejudicial to public health and public comfort,” and upon which report the bill of last session is founded, no notice is taken of Mr. Watt’s suggestions and inquiries. In the Parliamentary Report, to which we have just alluded, there are two inventions for the destruction of smoke, which appear to have principally occupied the attention of the Committee, and which profess to accomplish the object, with a very considerable saving of fuel, viz:
Mr. Brunton’s Fire Regulator. In this patent a newly constructed fire-place is applied to the engine boiler, containing a circular grate, which is made to revolve slowly upon its axis; the fire upon this grate is fed in front by a kind of hopper continually delivering small coal, which, from the rotatory motion of the grate itself, becomes equally spread upon its surface, so as to maintain a thin fire, and a sharp draught; the coal is thus rapidly decomposed and burned; the smoke at first produced having to pass across the grate, and over the red hot, and already coaked fuel.
Patent of Messrs. Parkes of Warwick.—The principal agent in this improvement is a current of air, admitted just beyond the end of the fire-place, by means of an aperture which may be increased, or closed at pleasure, and which the patentee term an “air valve.” A small fire is first made to burn brightly at the back of the grate; coals are then filled in towards the front, in which direction the fire gradually spreads; their smoke necessarily passes over the clear fire, where it becomes sufficiently heated to constitute flame, as soon as it meets with the current of air entering at the valve; and a striking experiment with this apparatus consists in alternately shutting and opening the air-valve, which is accompanied by the alternate appearance and disappearance of the smoke.
Instead, however, of insisting upon any form of fire-place, greater benefit would arise from an enactment respecting the height of chimneys; our intelligent reviewer, of whose remarks we have so frequently availed ourselves, observes, that by conveying black smoke, and other pernicious fumes into a capacious and very lofty chimney, much of the noxious matters that otherwise escape into the atmosphere are decomposed and precipitated or condensed within; of the truth of which, the chimney of the grand-junction engine, at Paddington, and that of the West Middlesex water-works, at Hammersmith, offer striking illustrations; when these machines are at work, the former produces little smoke, while the latter inundates the neighbouring gardens with perpetual showers of solid soot; and yet the only difference is in the relative altitude of the two chimneys; the boilers being, in all respects, set and constructed alike. A chimney from 150 to 200 feet would in most cases prove effectual, and the expense might be considerably lessened by making one shaft receive all the tributary fumes of many flues. But to return to the nuisance of breweries, from which we have made so long a digression; it is probable, that the smoke from these chimneys could not be remedied either by Brunton’s or Parkes’s patent, but the increasing the altitude of the chimney would seem to promise a mode of relief; we are also to look to the employment of steam as a substitute for fires; high pressure steam has been very extensively employed for this purpose in Whitbread’s brewery, and the smoke has in consequence sustained a very perceptible diminution.
(6) Sulphuric acid makers are continually indicted; and it would appear that by a scientific improvement in the process, the escape of the sulphurous acid, which constitutes the grievance, might to a great degree be obviated. How does it happen that, notwithstanding the cost of the materials necessary for the production of sulphuric acid, is in France at least double what it is in England, the French can afford to sell the article 25 per cent. cheaper than the English? the answer is obvious,—the great part of the materials are sent off into the air, in the form of sulphurous acid, and nitrous gas, to the annoyance of the neighbouring animals and vegetables, and the ruin, too often, of the proprietor. See Journal of Science and the Arts. In a report drawn up in the year 1806 by Guyton Morveau, and Chaptal, upon the subject of injurious manufactories, by command of the minister of the interior, it is declared that the distillation of acids can only prove dangerous from want of due precaution.
(7) The manufacture of Prussian blue is necessarily attended with highly offensive vapours. The first part of the process consists in mixing hoofs and tup’s horns with Russian or American potass, in large iron stills, to which heat is gradually applied, until the vessel become red hot; the animal matter and alkali being thus fused into a mass is laded out into iron pans, where it concretes into solid blocks, technically called metals.
(8) The operation of unfolding the cow’s horns by the application of heat is attended with a terrible stench; the trade in lanthorn leaves was formerly very considerable with Russia; but it was nearly annihilated by an edict of Catherine; the less flexible parts are made into combs; and the tips of the horns are sent to Birmingham for the manufacture of buttons.
(9) Owing to the viscid nature of the materials, it is impossible to make varnish without burning the animal matter, which occasions a stench of the most insufferable kind; and is so suffocating, that very lately two workmen lost their lives in a manufactory of this article in Gray’s-inn-lane.