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shall at once notice that the sulphuric acid given off from the 
combustion of coal is exceedingly large. 
Dr. Angus Smith, in his Eighth Report under the Alkali Act, 
gives some very important results of his investigations of emanations 
from chemical works. He shows the total escape of sulphur acids 
(calculated as sulphuric acid) from twenty-five chemical works. 
In some instances there was no escape of these acids; but the 
average loss of sulphur from the twenty-three works was rather 
over seven-and-a-half per cent on the total quantity burnt; and in 
four of the works, the loss was actually more than twenty per cent.; 
in one case it amounted to one hundred and fifty-nine pounds of 
sulphuric acid per hour. Probably since then there may have 
been some improvement; but, unfortunately, it pays the manu- 
facturers better to allow a large escape, and to work rapidly, than 
to have the necessary large chambers, and to condense the whole 
of the gases. 
Again, the burning of coal gas in dwelling rooms vitiates the 
air very much, both by the sulphur acids and the ordinary products 
of combustion ; because, although many towns—but by far from 
all—purify their gas very well, yet, unfortunately, the sulphur 
cannot by any practicable means be removed, and the consumers 
have to suffer from its effects. 
In addition to the injurious action which these sulphur acids 
have on animal life, they kill the trees and other vegetation for 
miles round, which, apart from their value in purifying the atmos- 
phere, convey that natural beauty to the scenery which we especially 
enjoy, andwhich must therefore be conducive to health. Conversely, 
the growing of trees in towns would be an easy matter if the escape 
of the sulphur compounds were prevented. It is evident that the 
inhabitants of towns—and especially of crowded towns, where no 
space is allowed for vegetation—however well their dwellings may 
be ventilated, are subject to much air-pollution, and it is therefore 
desirable that greater attention should be paid, not only to the 
consuming of the black smoke, but more especially to preventing 
the escape of the invisible products of combustion and waste 
chemical manufactures, 
