Page:Popular Science Monthly Volume 25.djvu/439

Rh recorded in the case of other dogs—that is not my point—but it does seem to me that this method of instruction opens out a means by which dogs and other animals may be enabled to communicate with us more satisfactorily than hitherto. I am still continuing my observations, and am now considering the best mode of testing him in very simple arithmetic, but I wish I could induce others to co-operate, for I feel satisfied that the system would well repay more time and attention than I am myself able to give. I am, sir, etc.,

—London Spectator.

Gas-Poisoning.—According to statements of Professor Pettenkofer at the recent Hygienic Congress in Berlin, the poisonous property of coal-gas depends upon its containing carbonic oxide in the proportion of about ten per cent, while the other constituents, although irrespirable, do not act as direct poisons. The danger in breathing the gas depends not so much on the duration of the exposure to a mixture of air and carbonic oxide as upon the amount of the latter contained in the air. Air containing only a proportion of five parts of carbonic oxide in 10,000 can be breathed for hours and even days by men and animals without any injury to health; while a proportion of seven or eight in 10,000 causes appreciable discomfort; of twenty in 10,000, difficulty of breathing, weakness, and uncertainty in gait; a proportion of twice that ratio leads to stupefaction, and higher proportions to extreme and fatal effects referable to the nervous system. Illness attributable directly to the entrance of gas into the house from the mains has been found to increase in the winter months, largely, probably because of the closing of the windows and the artificial heating of the rooms by which the gas is attracted into them. Dr. Pettenkofer has cited several striking instances of severe affection and even death that occurred in dwelling-houses in consequence of leakage from street-mains. At Roveredo, two sisters who slept in a basement contracted severe headaches during three successive nights. On the fourth night, which was a very cold one, the mother slept with them. None of the three appeared on the following morning, and on investigation the two sisters were found dead, and the mother so nearly so that she only survived a few days. The escaping gas, under the roadway, was thirty-five feet distant from the room. At Cologne, three persons in one family were killed in a single night in 1871, by a leak ninety-eight feet away. The superintendent of a prison in Breslau died and his sons were afterward found unconscious, in the same room, in 1879, from a leak thirty-five and a half feet away. Another instance has been recorded in Breslau, where the distance of the leak was one hundred and fifteen feet. At Cologne the gas passed through a sewer-channel and through the floor, while in the other cases it traversed layers of earth. The variation in the degree of cold between one night and another, causing corresponding differences in the force by which the gas is attracted to the rooms, would, in Dr. Pettenkofer's opinion, sufficiently account for the difference in the gravity of the effects produced on these occasions. Gas filtered through the soil from the mains may be quite odorless, at least until it has collected in large amount; and herein lies the danger to dwellers in the basement. On the earliest occurrence of such symptoms as headache, the windows should be thrown open; and if, on closing them again, the symptoms reappear, it may be suspected that gas is escaping into the house.

Dr. Crothers's Studies of Inebriety.—Dr. T. D. Crothers, of Hartford, Connecticut, read before the London Branch of the British Medical Temperance Society an historical paper on the study of inebriety in America. A fact of psychological interest pertaining to the subject is, that inebriety in this country moves in waves and currents, with a decided epidemic and endemic influence. This can be traced in the rapid increase of drunkenness in towns and cities, till after a time a reaction sets in, and a marked decline follows. "These waves of inebriate storms that sweep over large circles of country are always followed by intense revivals of temperance interest, and are fields of the most fascinating psychological inquiry yet to be studied." An increase of inebriety among our women is asserted as apparent