Page:Popular Science Monthly Volume 20.djvu/154

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sanitary agent. The French railway companies have for some time used it as a wash to cleanse their cattle-cars. In some countries it is employed as a remedy for certain affections of animals, and as a prophylactic against contagious diseases. These services, important as they are, are surpassed by those which this substance is made to render in the preservation of food. The quantities of the acid which are required for this purpose are very minute, and no case of injury to any person has been traced to it during the six years in which it has been in increasing use; yet some physicians have expressed the apprehension lest the continuous daily consumption of salicylized food may eventually produce derangement in the system. The subject deserves careful examination.

M. G. Hayem, having studied the physiological and medical effects of inhalations of oxygen, reports that when taken regularly, mingled with an indeterminate quantity of common air, oxygen produces an energetic stimulation of the nutritive faculties. It is especially beneficial to chlorotic patients, in whom it restores the appetite, stops vomiting, revives the movement of assimilation, and causes increase of weight. Inhalations of oxygen form a useful auxiliary in the treatment of chlorosis with iron, especially when gastric troubles make the application of this treatment more difficult. The inhalations are especially characterized by the control they exercise over vomiting, which is often suspended after one or two applications. They have also been observed to promote an increased elimination of urea.

Mr. G. S. Johnson has effected the synthesis of ammonia by passing a mixture of hydrogen and pure nitrogen over spongy platinum at a low red heat, when ammonia was produced at the rate of 5·9 milligrammes per hour. The experiment was varied in different ways, under one of which ammonia was produced at the rate of twenty-four, under another of three, milligrammes per hour, while in others none was produced. From all the experiments, Mr. Johnson has concluded that nitrogen, like phosphorus, may exist in two states, active and inactive, the latter being brought on by exposure to heat.

Catherine C. Hopley suggests in "Land and Water" a new theory of the so-called fascination of birds by snakes. It is that the bird mistakes the snake's tongue, which the animal keeps in constant motion, while it otherwise remains perfectly still, for a lively worm, and gazes at it with the expectation of making food of it. The idea was suggested by observations at the Zoölogical Gardens, where the birds were frequently seen watching the tongues of the snakes.

Attempts have been made in England, applying the principle of the Bessemer process, to facilitate the extraction of copper from the sulphuret by blowing air into the pyrites, in order to consume the sulphur and make it at the same time a source of heat for the continuance of the process of reduction. They have failed, because the bath would lose its heat as soon as the sulphur was consumed. The discovery has been made in a factory at Lyons, France, that the presence of a compound containing phosphorus will protract the continuance of the required temperature till the process is completed. The order of the combustion appears to be, first of the sulphur, next of the metallic impurities, lastly of the phosphorus.

The French Minister of Public Instruction has appointed a commission on hygiene of the eyes in schools, for the purpose of investigating the influence of the material conditions of the arrangement and furnishings of the school-room—the seats, desks, position of the light, etc., on the progress of myopia, and of looking for means of opposing them. Dr. Gavarret is president of the committee, and Dr. Javal is one of the members; and, in order that questions of typography may not be overlooked, it includes two publishers and a printer.

M. E. Bouchut has suggested the use of the digestive juice, papaine, which we have recently described, for the dissolution and digestion of the false membranes of diphtheria. He has, in his experiments, seen a thick, resisting, and elastic false membrane from the trachea which he had placed in a tube with one third part cf the juice of the papaya, dissolved in a few hours when cold, and in a few minutes when the tube was warmed. Since beginning his studies on this subject he has treated thirty-two cases of infants or adults, two of which were very severe, and lost only four.

M. Gley, a French physiologist, has, from experiments made upon himself respecting the effect of attention and intellectual work upon cerebral circulation, confirmed the results of M. Mosso and added some new observations. De finds that the rhythm of the heart suffers an acceleration which is increased in a direct proportion with the intensity of the attention. Thus the pulse was quicker when he studied geometry than when he studied philosophy, with which he was more at home. The carotid artery is also dilated during cerebral work', and the carotidian pulse becomes dicrotic, but the radial pulse becomes smaller and less ample. The phenomena of congestion observed in the brain persist for a certain time after cerebral activity.