CContinued from Vol. lxxv, page 20.] ยง It is with some reluctance that I refer to the "Theory of Ventilation." The past eighty years have witnessed the growth of chemical science, which, after passing through numerous stages of development, as witnessed by the different nomenclatures, has finally reached the point, that onlythe chemists of continual study can comprehend it, and at which point he who knows most about it is the least satisfied with its present condition.
But thirty or forty years since, chemistry was supposed to have unlocked the mysteries of matter, and by the extension of the simple rules applicable to the gaseous and metallic elements, it was thought that the cause of disease or health was to be discovered. Careful observers then examined, from the chemical standpoint, the constitution of the air, both fresh and vitiated; and writers, with good logical conclusions, enunciated a Theory, by which is was made evident that chemistry had uncovered the root of disease, and carbonic acid gas was the fatal cause.
The real facts are these : An adult in still life inhales each minute about 480 cubic inches of fresh air, and exhales 488 cubic inches of vitiated air~ of which vitiated air about 4 per cent. is carbonic acid, and from which about 19 per cent. of the oxygen originally supplied by the fresh air has been abstracted; the original quantity of vapor in the fresh air at mean temperature and hygrometric condition (62 ยฐ and 65 per cent.) will have been increased from 1"1 to 3'08 grains.
Carbonic acid gas was made the scapegoat. It killed dogs at the Grotto del Cane, as was happily exhibited to numerous travelers in Italy at that time--and both before and since, the same unfortunate dog serving to be killed, to the satisfaction of admirers, that had been resuscitated the day before, after the visitors' backs were turned. It was heavier than air, and in some conditions of temperature would not so readily diffuse, but form a layer of distinct gas, like water beneath oil. Altogether it answered the conditions of hypotheses, l Paper read before the Am. Institute of Architects, at Boston, Oct. 18th, 1877.