Page:Popular Science Monthly Volume 3.djvu/266

254 the symptoms of hydrophobia, and that, were it not for the common belief in canine virus, the spasms and other manifestations of the disease would not supervene. This view is confirmed by the fact that young children, who are not acquainted with the common belief as to hydrophobia, may be bitten by mad dogs and escape spasms and madness. He adds:

"If we are able, as in olden times, and in the case of children, to instruct or induce men to be perfectly quiet after they are bitten by a rabid dog, not to tremble or be frightened, but to banish anxiety, to control their imagination, and, with patience and hope, to look forward to recovery, and also to persuade the well to remain with the unfortunate one, and not to run away, but to cheer him in the hour of trial, then the means may have been discovered by which the effects of the accident are to be banished, and the poison in the wound neutralized."

Odorous and Liquifiable Gases: what Gases may be liquefied.—A writer in the Pharmaceutical Journal notes a remarkable relation between the odor of gases and their reducibility to the liquid or solid state. Thus oxygen, hydrogen, and nitrogen, which have no odor, cannot be reduced either by pressure or by cold. On the other hand, chlorine, which has a very strong odor, is easily condensed to a liquid. Again, the protoxide of carbon, being odorless, cannot be condensed, while the dioxide or carbonic acid, which has a faint, pleasant, and pungent odor, can be reduced to a liquid, and even to a solid state. Nitrous and nitric oxide, the latter of which is odorless, show similar phenomena. An exception to the general rule, that gases which are odorous are condensible, is furnished by acetylene, which, though having a faint garlic smell, has never been condensed. Usually condensability stands in a direct ratio to the strength of the odor possessed by a gas. Thus, sulphurous acid, which has a most intense odor, becomes a liquid under a pressure of two atmospheres, at 15° Fahr., while nitrous oxide, which has but a faint smell, requires fifty atmospheres, and a temperature of 7.2° F. A few gases having a fetid odor are exceptions to this law, but it holds good so generally, that a list of gases, arranged according to their reducibility, and another list arranged according to their properties of smell, will show a rough though marked coincidence.

The Spectroscope and the Bessemer Process.—Prof. Tidy, in a lecture on the spectroscope, thus briefly describes its important practical application in the Bessemer process: "Cast-iron contains a great amount of carbon, and in the Bessemer process this carbon is got rid of by burning it out of the molten iron with a blast of atmospheric air. The fluid cast-iron is placed in a large retort lined with refractory clay. This retort, the converter as it is called, turns on a pivot. Through the pivot a tube passes in connection with a very powerful blowing apparatus, by which air can be blown into the molten iron. That air burns out the carbon, the heated gases issuing as a flame from the converter. Now, it is very important to stop that blowing process directly the time arrives. Ten seconds too soon, or ten seconds too late, and the charge is spoilt. Experience, I grant you, does guide the worker, but experience is a costly thing; and this I am confident of: laud experience as you will, it will not weigh down the scale when we have in the opposite pan exact scientific experiment. The Bessemer flame, as it issues from the converter, is examined by the aid of the spectroscope. Numerous substances are visible—sodium, potassium, iron, hydrogen, carbon, etc. All of a sudden, in a second, the carbon-lines disappear, and that is the moment when the air-blast must be turned off, for now the carbon is burnt away, and the iron is converted."

New Material for Illuminating Gas.—Le Gaz, the gas-light journal of Paris, calls the attention of the directors of gas-works to a new illuminating material, vegetable pitch. This material is made by the Patent Oil and Stearine Company, of England, from the residues of the manufacture of olive, palm, cocoa, and other oils. In England it is widely used, being employed in gas-works in connection with coal, with a view to augment the volume of gas, as well as its illuminating power. The London Gas-light Company constantly employs it, mixing it in