Gaston Tissandier

“ A few years ago an English physicist, Thomas Andrews, was led to infer that, for permanent gases, there exists a critical point of pressure and temperature, above which they cannot be brought to the liquid state. This opinion is confirmed by Cailletet's experiments. Each gas requires that a certain pressure be combined with a certain reduction of temperature: either the one or the other of these two conditions might be employed separately without any effect, even supposing them to reach a high intensity. ”

“ A retired manufacturer, who at the same time is a distinguished man of science, M. Cailletet, has subdued the permanent gases, having succeeded in liquefying and solidifying them. This result, which is one of the most interesting achievements of our time, must unquestionably be regarded as a new and a grand conquest of matter by science.
Nearly at the same moment, another ingenious investigator and inventor, M. Raoul Pictet, reached the same result with regard to oxygen gas. We will pass in review successively the experiments of
Fig. 1.—Cailletet’s Large Apparatus for Liquefying gases. ”

“ The fruits of the study of meteoric astronomy prove that the surface of the earth is continually receiving cosmic materials either in the form of meteorites or shooting-stars, or of an impalpable dust. A ship passing to the south of Java in January, 1859, was assailed by a very fine ferruginous dust. Ehrenberg examined some of it with the microscope, and found that it was formed of melted globules of oxide of iron, and did not hesitate to regard it as consisting of particles of a mass of meteoric iron, which had been melted off by the operations of atmospheric friction. ”

“ The quantity of alcohol contained in rain-, snow-, and sea-water may be estimated at from one to several millionths of the whole. Cold water and snow-water seem to contain a little larger proportion of it than warm water. Appreciable quantities of it are found in the water of the Seine; and the proportion is very sensibly increased in sewer-water. Vegetable mold appears to be rich in it; and it is probable that the natural alcohol originates in the soil from the fermentation of the organic matters contained in it, and is thence diffused as a vapor in the atmosphere. ”

“ When all the sulphide of carbon has been burned, its place is taken by water, and the lamp goes out of itself; in the mean time the burning goes on with great regularity, and without any danger. About two and a half kilogrammes (six and a quarter pounds) of sulphide of carbon are sufficient for a room of a hundred cubic metres. The process is effective and economical enough; for sulphide of carbon is sold commercially for fifty centimes (about ten cents) per kilogramme, which gives about twenty-five cents as the price of disinfecting a room of a hundred cubic metres. ”

“ For several years I have paid attention to the study of atmospheric dust, and believe that I have proved that more or less considerable quantities of dust derived from cosmic bodies are constantly present in the air. ”

“ These bits of dust, lifted up and carried hither and thither by the atmospheric currents, must not be overlooked, for they play a part of considerable importance in terrestrial economy, and give rise to real geological formations. Clouds of impalpable dust, falling from the air in showers of considerable abundance, are not uncommon in some countries, and have been noticed in all periods of history. ”

“ Besides the grains of dust which may be seen in this manner, there are others that can be perceived only through the microscope, and others smaller still, little nothings like nebulosities in the sky, which seem to become more numerous as they are sought for with more powerful instruments. ”

“ Water turns into ice under the action of cold; into steam under the action of heat. Sulphur, phosphorus, the metals, and most solid bodies, may in like manner assume these three states. Chlorine, protoxide of nitrogen, carbonic acid, etc., may be liquefied or solidified. To this end we have only to bring the molecules nearer to one another by compressing them, or subjecting them to the action of cold. ”

“ L is a wrought-iron retort of sufficient thickness to withstand a pressure of 500 atmospheres. It contains chlorate of potash, and is heated so as to give off pure oxygen. It communicates by a tube with a sloping tube M, of very thick glass, one metre in length and surrounded by the carbonic-acid receiver H whose temperature is -140°. ”

“ If we pass these heights, into the extreme limits of the atmosphere, we shall find ourselves in the presence of dust from a new source—of that which is furnished by the combustion of incandescent aërolites. ”

“ Iodoform has marked characteristics which permit it to be distinguished very readily: the form of its crystals, particularly, is typical; it is of a light yellowish color, and appears under the microscope in the form of six-rayed stars derived from an hexagonal prism, of precisely the form of snow-crystals. ”

“ The tube is then taken away, and to its contents are added a little iodine and carbonate of soda; on heating it slightly, small crystals are precipitated of iodoform, a substance which could not be produced unless alcohol were present. M. Müntz has verified the results of this process by other test experiments. When distilled water, chemically pure, was heated in the same apparatus, the addition of iodine and carbonate of soda was not followed by any reaction. ”

“ These facts prove conclusively that the air holds in suspension minute microscopic particles of oxide of iron, some of which assume the form of well-defined spherules.
Similar spherules may be found everywhere in the dust of the air and in rain-water and snow-water. I have found them in the sediment of snow-water collected at the height of 8,800 feet on Mont Blanc (Fig. 4) . ”

“ They act on carbonic acid contained in a tubular receiver H. The pressure in this receiver is such that the carbonic acid in it evaporates at a temperature of -140°. The carbonic acid drawn out of it by the pumps is passed into the condenser K which is surrounded by the sulphurous acid receiver C, the temperature of which is -65°; it is there liquefied under a pressure of five atmospheres. The carbonic acid returns to the receiver H through the small tube k, in proportion as it assumes the liquid state. ”

“ This little experiment is not likely just yet to produce a revolution in the art of printing, but its success may enable us to judge, in some degree, how useful the insolators may be made in latitudes where the solar radiation is more intense and more constant than in Paris. ”

“ M. Pifre's insolator is shown in the center, with its great parabolic mirror. The engine which it drove is shown by the side of it, while on the right and in the foreground may be seen the press printing the journal. We have a right to believe that heliodynamics may at some future time be usefully and profitably employed in hot countries. ”

“ The only probable inconveniences involved in the application of this economical process arise from the danger of fire in case the furnace is badly constructed, and from the liability of the metallic objects that may be present to be tarnished. ”

“ M. A. MÜNTZ, of the French National Agronomical Institute, announces that he has discovered traces of alcohol as a natural product in cultivated soil, rain-water, sea and river-water, and the atmosphere. He has detected the product, it is true, only in the most
Fig. ”

“ E E', nuts which can be screwed off in order to adjust the apparatus before the experiment begins; A, ajutage; P P, two of the three very strong legs supporting the apparatus; S, support of the bell-glass G and the cylinder M; N, supplementary screw used to stop the mouth of the passage R, while the mercury is being poured into the apparatus.
We would remark that the enlarged lower end of the tube T is subject to an equal pressure within and without, and cannot break. It is only the upper portion of the tube that has to withstand the internal pressure, but its walls are very strong. ”

“ The principal improvement is in the form of the reflector, or insolator, by means of which the rays of the sun are concentrated upon the boiler or other object to be heated. M. Mouchot's reflector was in the form of a simple hollow cone, formed with a straight line of projection. ”

“ He has dissected the lungs of workmen who had labored in the mines for a greater or less length of time, and has found that this pulmonary obstruction goes on continually increasing till it becomes very dangerous. ”

“ He describes his apparatus as follows:
A and B (Fig. 1) are two compound exhausting and forcing pumps, so coupled as to produce the widest possible difference between the pressures of exhaustion and compression. ”

“ Fig. 4.—Corpuscles extracted by the Magnet from the Sediment of Snow-water on Mont Blanc, 8,800 Feet above the Sea. (500 Diameters.)
air-dust at the observatory of Montsouris under the direction of M. Marie-Davy.
Whence are these ferruginous particles derived? The spherules have been melted: we can prove this by burning particles of iron and observing them under the microscope (Fig. 5) ; those which fly off on the striking of a flint are like them (Fig. 6) . The spherules we are considering are probably derived from the showers of fire that escape
Fig. ”