Illuminating gas in its relations to health / by Edward S. Wood.

  • Wood, Edward Stickney, 1846-1905.
Date:
1877
Catalogue details

Licence: Public Domain Mark

Credit: Illuminating gas in its relations to health / by Edward S. Wood. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    odor evolved from it when removed from the purifier, so that exclusive puri- fication by wet lime has been generally abandoned. The dry lime process consists in passing the gas through moistened slaked lime placed upon trays. This is about as effective as the wet lime process, and is generally used in this country, but has been largely complained of as a nuisance where the works are situated in thickly settled districts, on account of the noxious and offensive odors evolved from the lime when removed from the trays, so that in New York city the companies have been compelled by the Board of Health either to resort to special apparatus for ventilating the lime and con- suming these gases, or to use the iron oxide mixtures for purification. In this city (Boston) a combination of the wet and dry lime processes is used. The wet lime through which the gas is first passed, and which retains most of the foul gases, is drawn from the purifier through a series of boxes and settling basins before the water finally comes into contact with the air when there is but little stench arising from it; and the dry lime, when spent and removed from the purifiers, has no unpleasant odor. The iron process never creates a nuisance. This consists in passing the gas through some mixture containing sesquihydrate of iron. The great ad- vantage of this is its cheapness, since the same mixture may be used over and over again. The sulphuretted hydrogen in the gas reduces the sesqui- hydrate of iron, to form water, sulphur, and hydrated sulphide of iron, which last, on exposure to the air, is changed again to sesquihydrate of iron, and more sulphur is set free. This process is adopted very extensively in the European works on account of its economy. The difference between the action of the lime and that of the iron mix- tures appears to be chiefly that, while the lime removes from the gas the impurities which it contains, perhaps better than the iron mixtures, yet, upon the opening of the purifiers, it permits the offensive and noxious sulj^hur- ous gases, like sulphide of ammonium, to escape into the atmosphere, be- come diffused throughout the neighborhood, and act as a nuisance, much more readily than the iron purifier does, which fixes the sulphur by com- bining with it. So that, where works are situated in thickly settled districts, the principal portion of the noxious constituents of the gas should be re- moved by wet lime before the gas passes through the dry lime, as in this city, and the blue billy, as the wet lime residue is called, disposed of in such a manner as not to become a nuisance ; or the dry lime should be thoroughly ventilated before the purifying boxes are opened, or recourse should be had to the iron mixtures. Gas thus made consists chiefly of hydrogen (40-50%), marsh gas (35-45%), carbonic oxide {\\-']\%)., olefiant gas and other hydrocarbons (4-8%), and usually very small amounts of carbonic acid and air. Cannel gas has about the same composition, the proportion of the hydrogen, marsh gas, and olefiant gas being a little different. Gas made from petrokutn or naphtha need not occupy our attention, al- though it is made quite extensively in many of our large cities for enrich- ing purposes, since when made from Pennsylvania petroleum it contains no sulphur or ammonia, and requires no purification ; and I have heard it i