In the fermentation of corn, for making malt liquors or ardent spirits, a large quantity of carbonic acid is generated, and workmen who heedlessly descend into the vats to cleanse them, are very often suffocated. The trial by a lighted candle should never in such cases be omitted. In the burning of lime there is a very large proportion of carbonic acid set free; and poor persons who are tempted to sleep on the platform of a lime-kiln for the sake of the warmth it affords, are sometimes suffocated by the vitiated air they breathe. The air, so far as regards its influence on health, is modified in a very important manner by causes which are not so positively known and measured as those we have hitherto examined. The spreading of odours through the air, whether they be the "spicy gales of Araby the blest," or the more unwelcome indications of putrescent matter, takes place by means of quantities of substances so small as to defy the powers of detection we possess. Many diseases, it is well established, arise from the formation and diffusion through the air of peculiar poisons in amazingly small quantity. Thus ague is produced by a specific poison generated in marshes. These poisons resemble other ordinary poisons, inasmuch as we can decompose them, and thus destroy their power. The chemical substance chlorine decomposes almost every vegetable or animal material that it touches. Thus it destroys all colours, and is hence of the greatest use in bleaching; it also destroys all atmospheric poisons, and, consequently, in hospitals and in private houses it is used to disinfect or prevent the spreading of disease, by decomposing the material which conveys it through the air. For change of air we therefore, with reason, go to the country when we can; but whether to the sea side or to the interior, to Enniskerry or Kingstown, is not dependent on the nature of the air. Wherever the invalid finds most amusement, and agreeable occupation which does not fatigue; wherever the beauty of scenery, and the society of those to whom the heart is bound in ties of mutual esteem and love, present to the mind of one harassed by intense exertion of thought, or broken down by disease of body, a relief in admiration of the wisdom and goodness of his Creator, and in sympathy and kindliness towards his fellow men, the atmosphere is clearest; the bracing, enlivening influence of the pure country air is the most sensible, and the mind and body are most effectually restored to the condition of perfect health.