House, Croydon, June 5, 1882, he says: "I have abundance of evidence that scarlatina is distributed by sewers, or rather that the germs which grow it are conveyed with sewer-air. If, however, the constitution of those receiving the germ is not fitted to grow it and to lead to its fructification, no fever will arise, and the germs will abort. It will not develop in ordinary flesh and blood, but requires that the recipient should be in a special state as regards his own blood to enable it to mature."
In addition to the evidence now presented, and which might be greatly multiplied, as to the probability, or, as perhaps most physicians think, the certainty, that typhoid fever, diphtheria, and scarlatina are thus caused or distributed from house to house, there is the negative testimony presented in the fact that these three terrible maladies are seldom seen in those Eastern Asiatic cities where "modern improvements" in plumbing are unknown, and that with us they have increased just in proportion to the extension of these "improvements."
It is quite probable, if not actually demonstrated, that Asiatic cholera is often propagated in the same manner. The length of time its germs survive after being thrown off from the body, and the established fact that the excreta are known to contain and convey the germs, increase the presumption that it may be distributed by the sewers, if indeed it does not render it absolutely certain.
Finally, no good reason can be given why every zymotic disease may not in this manner, at certain times and under certain circumstances, be widely distributed, although no doubt the liability of such distribution must depend much upon the viability of the germs and upon other circumstances.
What are the practical difficulties in the exclusion of sewer-gas where plumbing is extensively distributed through our dwelling-houses and is there at present any ground of encouragement that they will be overcome?
The Water-Traps.—Professor Doremus illustrated to the Academy by experiment that gases would pass through water in water-traps, although there was free ventilation on the opposite side.
The applicability of these experiments to the question of the passage of sewer-gas and bacteria through water-traps has by some been denied, and especially on the testimony of the experiments of Carmichael, of Glasgow, in which experiments sewer-gases passed through well-sealed and ventilated water-traps in only a small amount, and bacteria were excluded altogether.
I am not a chemist, and this question I prefer to leave with those who are alone competent to decide it.
Some experimenters, however, have not obtained the same results as were obtained by Carmichael, Dr. Billings, and others. R. S. G. Paton, Ph. D., Chemist to the Health Department, city of Chicago,