(b) The Air of Graveyards contains an excess of carbonic acid. The older intramural graveyards appear to have been a cause of illness; but modern graveyards, kept under good regulations have never been shown to cause illness.
(c) The Effluvia from Decomposing Carcases, especially of horses on the battle-field, have led to outbreaks of diarrhœa and dysentery among the soldiers.
(d) The Effluvia from Manure and Similar Manufactories do not seem to injure the workmen as a rule, but attacks of diarrhœa have been produced in the neighbourhood when the wind has wafted the effluvia towards any particular part. Sore throat, and occasionally diphtheria, have been ascribed to the inhalation of London manure taken into Essex.
(6) The Effluvia from Certain Manufacturing Processes seem to be rather nuisances than actually productive of ill health. The vapours given off by tallow-making and bone-burning processes are most disagreeable, but there is little or no positive evidence of their direct insalubrity.
The air of brickfields and cement works is peculiarly disagreeable.
The Degree of Moisture and the Temperature of air are of great importance in relation to health. Air which is unduly moist or dry, hot or cold, may be injurious apart from any foreign matters it contains.
The relative amount of moisture is of greater importance than its actual amount. An atmosphere which contains aqueous vapour up to the point of saturation is very oppressive; the normal evaporation of insensible perspiration (and with it of the organic impurities removed from the skin) is interfered with; and consequently the “oppressiveness of the day” is complained of.
An unduly hot air is generally productive of pallor and ill health, though it is difficult to know how much to ascribe to the high temperature, and how much to the commonly coexistent vitiated atmosphere. The temperature of living-rooms ought not to be over 60° to 65° Fahr., and of bedrooms not over 60° Fahr.
The devitalising influence of extreme cold is well known. Its effects are more particularly seen in young children and the very old, who require to be carefully tended during severe and long-continued cold weather. Dry, cold weather, with the temperature near the freezing point of water, and a cutting east wind prevailing, is not uncommonly described as “bracing.” This is so far from being the case, that it requires all the vital powers of the strong and healthy to resist its depressing influence, and the feeble of both extremes of age succumb.