SEA-Air, that part of the atmosphere which is above the sea.
Sea-air has been found salubrious and remarkably beneficial in some distempers. This may be owing to its containing a greater portion of oxygenous gas or vital air, and being less impregnated with noxious vapours than the land. Dr Ingenhousz made several experiments to ascertain the salubrity of sea-air. By mixing equal measures of common air and nitrous air, he found that at Gravesend, they occupied about 1.04, or one measure and of a measure: whereas on sea, about three miles from the mouth of the Thames, two measures of air (one of common and one of nitrous air) occupied from 0.91 to 0.94. He attempted a similar experiment on the middle of the channel between the English coast and Ostend; but the motion of the ship rendered it impracticable. He found that in rainy and windy weather the sea-air contained a smaller quantity of vital air than when the weather was calm. On the sea-shore at Ostend it occupied from 0.94 to 0.97; at Bruges he found it at 1.05; and at Antwerp 1.09. Dr Ingenhousz thus concludes his paper:
It appears, from these experiments, that the air at sea and close to it is in general purer and fitter for animal life than the air on the land, though it seems to be subject to the same inconstancy in its degree of purity with that of the land; so that we may now with more confidence send our patients, labouring under consumptive disorders, to the sea, or at least to places situated close to the sea, which have no marshes in their neighbourhood. It seems also probable, that the air will be found in general much purer far from the land than near the shore, the former being never subject to be mixed with land air.
Dr Damman, an eminent physician and professor royal of midwifery at Ghent, told Dr Ingenhousz, that when he was formerly a practitioner at Ostend, during seven years, he found the people there remarkably healthy; that nothing was rarer there than to see a patient labouring under a consumption or asthma, a malignant, putrid, or spotted fever; that the disease to which they are the most subject, is a regular intermittent fever in autumn, when sudden transitions from hot to cold weather happen.
People are in general very healthy at Gibraltar, though there are very few trees near that place; which Dr Ingenhousz thinks is owing to the purity of the air arising from the neighbourhood of the sea.
Most small islands are very healthy.
At Malta people are little subject to diseases, and live to a very advanced age.