SCIENTIFIC NOTES.

Globe, Volume IV, Issue 328, 1 July 1875, Page 4

SCIENTIFIC NOTES.

( Chambers' Journal, April 30.)

Ever since) ventilation was first talked and written about, it has been a more or less obscure and uncertain subject; a subject on which it was easier to show what ought to be than what cotild be. We have, therefore, the more satisfaction in calling attention to a paper by Dr Frangois de Chaumont, of the Army Medical School, Netley, which lays down definite principles of ventilation, and will enable any observant person to decide whether a building is properly ventilated or not. The paper in question “On the Theory of Ventilation : an attempt to establish a positive basis for the calculation of the amount of fresh air required for an inhabited air space”—was read at a meeting of the Eoyal Society, and has been published in their “ Proceedings,” and is thus available to all who desire to make use of it.

The basis taken by Dr Frangois de Chaumont is “ the evidence of the senses,” but with “proper care and precautions.” The poison in impure air, he remarks, is organic matter, either suspended or in the form of vapour; and it is this poison which imparts to air that disagreeable quality commonly described as “ close.” This closeness can be remedied only by diluting the confined air with a quantity of fresh air, and to determine this quantity is one of the steps in a theory of ventilation. Observation shows that the “ amount of organic impurity bears a fairly regular proportion to the amount of carbonic acid evolved by the inhabitant in an air space. This being accepted, and general diffusion being admitted, we can easily calculate the amount of fresh air required to bring down the carbonic acid to some fixed standard. If, now,” continues the doctor, “ we adopt as our standard the point at which there is no sensible difference between the air of an inhabited space and the external air, and agree that this shall be determined by the effects on the sense of smell, our next step is to ascertain from experiment what is the average amount of carbonic acid in such an air-space, from which we can then calculate the amount of air required to keep it in that condition. But as the sense of smell is very quickly dulled, each air-space to be examined ought to be entered directly from the open air.” By observations in hospitals and barracks in different parts of the country, Dr Frangois de Chaumont has arrived at conclusions, and obtained data on which to base his theory. Under the several heads ; Fresh—fair—not close—close —very close—extremely close, he records his observations in a way which will enable any one interested in the subject to test them for himself. The conditions laid down in the paper as “ the standard of good ventilation” are, that the temperature should never be very much below sixty degrees—Vapour ought not to exceed 4.7 grains per cubic foot, at a temperature of sixty-three degrees, or 5.0 grains at a temperature of sixty-five degrees—Humidity (per cent) ought not to exceed seventy-three to seventy-five— Carbonic acid: respiratory impurity ought not to exceed 0 0002 per foot, or 0-2000 per thousand volumes. Another point established by this inquiry is that, where disease prevails, more fresh air is required than in health ; hence, hospitals demand more pure air than barracks. As Mr F. J. Bramwell said in his annual address to the Institution of Mechanical Engineers : Do we in our applications of power make as much use of wind, water, and waves as we ought, remembering that their power may be transmitted to a distance 1 “ Do we,’ he asks, * resort to any large extent to sources of power in nature other than coal ? Is it not the fact that mechanical invention has gone back in these matters rather than forward ? And do we utilise that primary source of power, the heat of the sun—the current heat from year to year —making the most of barren hillsides, as it seems to me we might do, by planting quick-growing trees, which, fostered and matured by the sun, would yield large quantities of wood to be used as fuel for domestic purposes ? Are we estimating at their full value the deposits of peat, and are we not tempted to pass by this large store of fuel because its use is attended with difficulties ? Is it not true that we use coal in the most grossly wasteful manner? How much of the fuel goes up the chimneys of our furnaces unconsumed, in the form of visible carbon, or in the worse, because less readily detected, form of invisible carbonic oxide? In the face of such faults and errors, Mr Bramwell argues that it is the duty of mechanical engineers, “ by precept, practice, and example, to do all that lies in their power to cause all to respect and understand the value of that which they have too long lightly treated and grossly abused.” At the Bute Docks, Cardiff, the machinery for lifting out ballast and putting in coal is so efficient, that it is now not uncommon for a steam collier of fifteen hundred tons to enter the bash at high water of one day, discharge her ballast, take in her cargo of coal, and leave at high water the following day, the entire operation having lasted less than twenty-four hours. Sir David Solomons has invented a method of signalling on railways which, as he believes, will prove effectual in preventing

mistakes and accidents. Electric apparatus and bells are to be fitted on the engine and in the guard’s van with intercommunications. A light continuous bar or rail, insulated through its whole length, is to be laid down down between the rails, not to bear weight, but only that a light wheel connected with the engine may run upon it. This continuous bar may be connected with sig-nalling-apparatus in all the stations; and thus while the electric wheel of the engine touches the bar, and connection is made with the electrical apparatus, signals can be sent from the engine to the stations, from stations to signal stands, and from one locomotive to another. Collisions, as Sir David states, could not happen, because when a train comes within a certain distance of another, either before or behind, a bell rings, and warns the engine-driver. From these particulars a general notion of the method may be formed ; but it is difficult to understand without diagrams. A model is, however, in course of construction, which, when finished, will demonstrate the capabilities of the mechanism and of the method.

Is the patient really dead or not ? is at times a very anxious question. A medical practitioner ol Cremona proposes a simple method by which the question may be answered with certainty. It is, to inject a drop or two of ammonia beneath the skin, when, if death be present, no effect, or next to none, is produced ; but if there be life, then a red spot appears at the place of the injection. A test so easily applied as this should remove all apprehension of being buried alive,

The oft-expressed wish, that glass would not break, seems about to be realised, for a manufacturer at Pont d’Ain has discovered a means by which glass can be made almost, though not quite malleable. It is to a peculiar method of annealing that the increased strength is due, and the amount of strength may be judged of from the fact, that a pane of ordinary window-glass annealed by the new process remains unbroken when a fivefranc piece falls on it from a height of six feet. Already, as we hear, a company has been formed to manufacture this new glass on a large scale. We learn from the Utah journals that a measuring pillar, after the manner of the Kilometer, has been set up on the brink of the Great Salt Lake. This has long been wanted, for the rise and fall of the waters of that lake are extraordinary and mysterious, and physicists have often urged the erection of some means of recording the amount, The valley was first settled in 1847. During some years there were small fluctuations in the level of the lake; but from 1862 to 1868 the water rose twelve feet, and this increase, with occasional ups-and-downs, it still maintains. For years the road to the salt-pans has been twelve feet under water, and an observer on the- spot remarks, there seems to be “an irrepressible determination of the waters to rise. The mountain streams are steadily enlarging. The'humidity of the atmosphere annually increases as the area of cultivation in the valleys becomes greater, and, as a consequence, the evaporation less. Tens of thousands of acres of farming, meadow, and pasture lands have been submerged along the eastern and northern shores of the lake. Many square miles of valuable lands as yet available and occupied by the farmer, skirting the lake, would be completely drowned, should the rise continue,” It has been remarked that certain Tartar tribes who drink freely of koumiss, or fermented mare’s milk, are free from that distressing malady, pulmonary phthisis. This fact has led to trial of the experiment whether the disease could be cured by doses of koumiss artificially prepared ; and with a satisfactory result. The artificial koumiss, composed of ass’s milk and cow’s milk, is a lively sparkling beverage, not very palatable; but in three or four days the patients tolerate it, “ and then unequivocal signs of amelioration set in, the appetite returns, vomiting ceases, flesh is gained, and good sleep is enjoyed.” More on this subject may be found in the Bulletin de Therapeutique, 1874.