METEOROLOGY. CHAPTER I. 1. Meteorology defined. 2. History; Superstitions of the Ancients. 3. General considerations. 4. Rise of Pneumatic Chemistry. 5. Composition of the Atmosphere,-Oxygen and Nitrogen. 6. Carbonic Acid. 7. Adventitious products. 8. Ratio of Oxygen and Nitrogen constant. 9. Distribution of these Gases. 10. Their physical properties,-Oxygen, Nitrogen. 11. Carbonic Acid Gas. 12. Nitrogen found free in South America. 13. Carbonic Acid free in several localities. 14. Grotto del Cane. 15. Valley of Death in Java. 16. Considerations on the quantitative composition of the atmosphere. 17. Speculation of Brongniart. 18. Source of the renewal of Oxygen consumed. "O Nature! how in every charm supreme! Whose votaries feast on raptures ever new; O for the voice and fire of Seraphim, To sing thy glories with devotion due!" BEATTIE. 1. METEOROLOGY is the science which acquaints us with the various phenomena of the atmosphere. It leads us to inquire into its properties and relations. 2. On entering upon the study of any science, it is usual to trace its history; but upon that of Meteorology, little information is cast by the records of antiquity. The observations of the ancients were directed chiefly to changes in the weather; and by personal assiduity, they were enabled to prognosticate often with considerable certainty. The philosophers of old were willing to explain the phenomena by the most vague hypotheses,-by stellar and planetary influences. In those times there were found some who were believed to possess supernatural influence over atmospheric meteors. Thus the priests of Samothrace, the Thracean Samos, famous for its deluge, and renowned for the antiquity of its mysteries, promised auspicious winds to such as consulted their sacred oracle; and Empedocles of Sicily boasted in his song of a knowledge of the mystic art. The priests of Jupiter Lycæus, were wont to sacrifice at the fountain Hagno in Ar cadia, in the time of drought,-touching the water with the oaken wand, presently a vapour rose, and forthwith there descended a pleasant rain! Even in more recent times, such. powers were believed to be given to mortals; for, in the reign of Constantine, we find Sopater of Apamea put to death because he was supposed to have stilled the winds, and thereby caused the plague which then raged at Constantinople! 3. The atmosphere, though invisible and intangible, is nevertheless a body which cannot elude the grasp of the philosopher. It is a ponderable substance, with whose properties he is familiar. It is obedient to refined analysis, and refuses not to be called by its name when the constituents are again united. It crouches under pressure, regains its original capacity when the load is withdrawn, and becomes more bulky when the weight which it naturally bears is diminished. Thus can he make it heavier or lighter; he can withdraw from or add to its humidity, and vary the amount of its caloric; he can study its electricity, and at will possess himself of that powerful agent. What can he not do with it? But after all-he is ignorant. With Laplace may he say-" that which we know is little, but that which we do not know is immense." 4. The atmosphere was supposed by the ancients to be an elementary body, and was classed with fire, and earth, and water, as ingredients into which all material bodies could be resolved. It was not until about the middle of the 18th century, that Boyle, Hooke, and Mayow, doubted its being a simple fluid; and the knell of that cycle had nearly rung, before the discovery was experimentally made by Cavendish, Lavoisier, and Scheele. This was a remarkable scientific epoch: Chemistry awoke from the sleep of alchemy, and one discovery after another rewarded the patient observer for his persevering labour. Cavendish, Priestley, and Watt, laid the foundation of Pneumatic Chemistry; Lavoisier raised the structure. 4 5. The atmosphere is composed of aerial fluids, chiefly oxygen' and nitrogen,' in the ratio of one volume of the former to four of the latter; or, more correctly, one hundred parts of atmospheric air contain 20.8% of oxygen, and 79.2% of nitrogen. Such is the result of numerous analyses by Cavendish,' Berthollet, Gay Lussac, Humboldt, Davy, Dumas, Brunner, and Boussingault. Thomson, by chemical analysis of air, and electrical synthesis of water, by means of hydrogen introduced into a measured quantity of atmosphere as proposed by Volta, found the ratio of these gases to be as one to four; and this harmonises with the view of Gay Lussac regarding ratios of the union of gases. Thus employing the atomic theory of Dalton, air would be composed of one atom of oxygen and two atoms of nitrogen, and its atonic weight =8.013+ (2 x 14.19)=36.393, hydrogen being represented by unity; but if, according to the Continental notation, we take oxygen as the standard, 100, then the atomic weight of atmospheric air will be 100+ (2 × 177.04) = 454.08. = 6. To these gases is added a variable quantity of carbonic acid gas,' about one volume to 2000 of atmospheric air. This gas is widely diffused, for M. de Saussure ascertained its presence on the summit of Mont Blanc, and Baron Humboldt detected it in the air collected by Garnerin in a balloon at an altitude of 4280 feet. Saussure1o found by numerous experimental inquiries that at Chambeisy, near Geneva, in that city, and over the Leman lake, the average quantity was 4.9 by vol. in 10,000 at mid-day. The range was from 3.7 to 6.2. In summer the amount was greater than in winter; and in 1 Oxygen-Lavoisier; Empyreal air-Scheele; Dephlogisticated air-Priestley; Vital air-Condorcet. 2 Nitrogen or Azote, the phlogisticated air of Priestley. 3 Phil. Trans. Lond. 1783. First Princip. of Chemistry. 'Carbonic acid gas, the Fixed air of Black. * Voyage dans les Alpes, tom. iv. 199. In the year 1802. See Mém. d'Arcueil. tom. ii. 233. "Jour. de Phys. tom. xlvii. 202. 10 Annales de Chimie et de Physique, xxxviii. 411; Ib. xliv. 5. December, January, and February, it bore to June, July, and August the ratio of 77 to 100, the observations being made at noon. He likewise observed that the maximum occurred during the night; that it was greater over a dry than a wet soil; and greatest in the superior strata of the atmosphere. Considerable doubt rests upon the accuracy of these experiments. Thenard' found, by means of barytes water, that 10,000 vol. of air contained 3.91 vol. of this gas. Dalton,' with lime water, estimated the quantity at 6.8 vol. in 10,000 of atmospheric air. According to recent observations by Boussingault and Levy at Andilly, near Montmorency, sixteen miles from Paris, and in that city, between the 29th September and 20th October 1843, it appears that the quantity of carboinc acid gas in 10,000 volumes of the atmosphere, was at Paris 3.253, and at Andilly 2.989 vol., or as 100 to 92. The experiments were performed at each place at the same hour, and upon the same quantity of air, viz., about 450 pints, which gave at Paris 0.826 grammes, = 12.76 English grains, and at Andilly 0.797 gram. = 12.31 English grains of carbonic acid. Vogel' asserts that the atmosphere over the ocean contains less of this gas than over the land. 7. In addition to these gases, aqueous vapours, the product of oxygen and hydrogen chemically combined, and various adventitious odours, are always floating about in inconstant quantities. These chiefly arise from the outcast of our manufactories, and decaying organic products; and were a process of purification not constantly going on in the great laboratory of nature, our atmosphere would be no longer innocuous, and under its deadly influence life would languish and expire. It shall be presently observed, that much oxygen is furnished by the infusoria, and by a process of deoxidation from carbonic acid. Thus, by means of oxygen, which possesses the power of readily combining with all the elements, fluorine probably excepted, and most compound substances, the atmosphere is freed from adventitious matters, and pre 2 Traité Elem. de Chimie, tom. i. 303. Philosophical Mag. xxiii. 354. 3 Dumas, Acad. de Sc. de Paris. Annals of Philosophy, No. 5; Journal de Pharmacie, No. ii. 501. served in a state of purity. According to Baron Liebig,' there is always present ammonia' derived from the decomposition of organic matters, from which gas, the nitrogen of plants, is supposed to be obtained. From the great affinity of ammonia for water, it will not be found free in a humid atmosphere. Its presence in meteoric water may be shewn by adding hydrochloric or sulphuric acids and evaporating nearly to dryness, when the peculiar pungent odour of ammonia will appear on addition of a little lime. According to Gieger it exists in the atmosphere in combination with carbonic acid. The ammonia may become oxidised and give rise to nitrous and nitric acids, occasionally met with in rain. This may be effected in all likelihood by the electricity of thunder-storms. Dr J. Murray has detected nitrous acid in the atmosphere by means of the tincture of Campechia wood. The presence of this acid may explain why milk and other organic substances easily pass to the acetous stage of fermentation during high electric excitement. Cavendish, by passing electricity through atmospheric air in glass globes hermetically sealed, obtained the red fumes of nitrous acid, an effect which may be produced by the electricity of the clouds. Chevallier noticed in the air over Paris, ammonia and organic matters, and in London sulphurous acid. Boussingault' adds a very minute quantity of carburetted hydrogen. Hydrochloric acid and its salts have been detected by the shores of the Mediterranean and the Baltic'. Air from the bassins de Montfaucon has been observed to contain ammonia and its hydrosulphuret; and that from the fosses d'aisance of Paris 1 Organ. Chem. of Physiol. and Agricult. "Ammonia,-Volatile Alkali. 3 vols., condensing into 2 vols. Composed of nitrogen 1 vol. and hydrogen The hydrochloric acid The rationale of the process is easily understood. unites with the ammonia through its affinity for that substance, and hydrochlorate of ammonia (muriate) is formed; when to this salt carbonate of lime is added, decomposition takes place, hydrochlorate or muriate of lime results, and the ammonia escapes with the carbonic acid of the lime. Phar. Times, vol. i. 259. Ann. de Ch. et de Phys. 1834, tom. lvii. 171; moires de l'Institut Royal de France, 23 Août 1834. * Foderé, Voy. aux Alpes Maritimes, tom. ii. 256. Archiv. des Pharm. xliv. 35. |