The principles of ventilation and heating and their practical application / by John S. Billings.

  • Billings, John S. (John Shaw), 1838-1913.
Date:
1884
Catalogue details

Licence: Public Domain Mark

Credit: The principles of ventilation and heating and their practical application / by John S. Billings. Source: Wellcome Collection.

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    is not probable that the architect will ever have occasion to make any such arrangements for its disposal. In what would be termed pure country air, carbonic acid is present in the proportion of about 4 parts in 10,000. In a crowded and confined space, such as the pit of a theatre and in some school-rooms, its pro- portion has been found to rise to 30, 40, and even 100 parts per 10,000. Pure carbonic acid gas may be present in air in a proportion as high as 150 parts per 10,000, without producing discomfort or giving any special evidence of its presence, as, for instance, in those establishments where sparkling mineral waters are bottled, or soda fountains are charged, or in vaults where champagne is bottled, in certain rooms in breweries, or in some celebrated baths and health resorts. It is evident, therefore, that carbonic acid gas—in the proportions in which we find it in our worst ventilated rooms—is not in itself a danger- ous impurity; in fact, we have no evidence to show that in such propor- tions it is even injurious. What, then, is the importance of this gas in relation to questions of ventilation ? and why do sanitarians lay so much stress upon the re- sults of chemical tests of air with reference to this substance, and on what may seem very small variations in the proportions in which it is present ? It is because carbonic acid is usually found in very bad company, and that variations in its amount to the extent of three or four parts in ten thousand indicate corresponding variations in the amount of those gases, vapors, and suspended particles which are really offensive and danger- ous, and also because we have tests by which we can, with compara- tive ease and certainty, determine the variations in the carbonic acid, while we have no such tests of recognized practical utility for the really dangerous impurities. As a matter of convenience, therefore, we measure the carbonic acid, and thus get a measure of the extent to which ventilation is being effected. Of course, we must make sure that the circumstances of the case present nothing unusual, since, on the one hand, carbonic acid may be present in great excess—as in a soda-fountain-charging room—with- out indicating great impurity ; and, on the other, it is possible that the air of a room may be very dangerous, from suspended organic particles, and yet have carbonic acid present in merely normal amount. This will appear more clearly when we come to consider the ventilation of hospitals for infectious diseases. But while the quantity of carbonic acid which is contained in some of our worst ventilated rooms is not injurious to human life, the amount