[Footnote 5: Cooper's edition of Good's _Study of Medicine_, vol. i. p. 358.] [Footnote 6: _Philosophical Transactions_, No. 457.] * * * * * VENTILATION. (Vol. ix., p. 415.) "Airs from heaven or blasts from hell." The mistake which, it is very respectfully submitted, the professed ventilationists fall into, and which may be considered the _fons et origo malorum_, is the notion that foul air rises upwards, and that pure air comes from below; which is just the reverse of the fact. In any room containing animals or vegetables, the air undergoes a change by respiration. Leaving the vegetables to care for themselves, and considering the animals, if such a title may be reverently given to members of the House and others shut up in confined apartments for the benefit of their species, it is obvious that the pure air of heaven must undergo a change by the respiratory organs of the members, which change is absolutely necessary to preserve their lives, and each such apartment is a manufactory for converting pure into foul air. Its steam-power is seated in the lungs, which, at each inspiration, take up the oxygen (the principle of life and flame) of the air, and at each expiration give out the carbon of the blood, conveyed by the veins from all parts of the body as refuse, and when purged therefrom by oxygen inspired, convert the venous blood into arterial, and bring life out of death. What, then, becomes of the expired carbon? The professional ventilationists say it _ascends_, and they provide mechanically, but not scientifically, accordingly. On the contrary, it finally _descends_; and this is the reason why our beds are always a few feet above the floor. If proof is needed, it may be found by applying a candle to the door, slightly ajar, of a room occupied by a few persons, when it will be found that the flame of the candle will point, when held at the lower part of the door, outwards, and at the upper part of the door inwards, showing how the currents of air pass; and as every one knows carbon to be heavier than air, the lower current is the one charged with carbon. The _Grotto del Cane_ derives its name from the fact, that a dog passing the stream of carbon issuing from the fissure in the rock, dies; whilst a man walking erect, with his mouth above the stream of carbon, escapes. Our lime-kilns furnish a common example of the fact of the density of carbon compared with atmospheric air. Experiments in proof are constantly exhibited in chemical lectures. The practical inference, _experto crede_, is that holes in the skirting-boards should be made so as to draw off the foul air, whilst the angelic visits of pure air should be sought from above. Bellows, such as are used in diving-bells, with hot or cold air, might be necessary in an extreme case--long debates in the Commons, for example,--which may require extraordinary ventilation. T. J. BUCKTON. Lichfield. * * * * *