Art. XIII. Observations on Salt Storms, and the Influence of Salt and Saline Air upon Animal and Vegetable Life.
Art. XIII. Observations on Salt Storms, and the Influence of Salt and Saline Air upon Animal and Vegetable Life. Read before the Lyceum of Natural History of New-York, March 7, 1819, by John B. Beck, M. D.
(Communicated for this Journal.)
Meteorology is a science of so much general concern, that it seems to be incumbent upon every member of society to aid in augmenting the stock of facts, which the labours of ingenious and scientific men have already accumulated on that subject. Under this impression I propose to devote the following paper to some observations on salt winds or storms, as they have occurred in this country and in Europe—a subject, which although presenting many phenomena of a more than temporary interest, has as yet excited but little attention. Indeed, the opportunities for observation have occurred so rarely as readily to account for its having in a great measure escaped the philosophical acumen of the present age.
It must have been early observed that the atmosphere in the vicinity of the sea frequently becomes impregnated with saline materials; but the first and only account of a salt storm that I have met with, is to be found in the Transactions of the Linnæan Society of London. The 8th volume of that work gives an interesting narration of the effects of a storm of this description, which occurred in England, in January, 1803. It was occasioned by an east wind, which blew for some days, and which, in its passage over the ocean, had imbibed large quantities of salt water, which were afterward deposited upon the land. In most cases these depositions proved fatal to the plants and vegetables which received them. So extensive were the effects of this singular storm, that they were felt in the vicinity of London, at a distance of about seventy miles from the ocean, and in all the intermediate country. In most instances, the leaves of the plants, which suffered from it, appeared as if they had been scorched, and in some places even the tops of the branches mortified. A storm of the same kind took place in England, in February, 1804; and the memoir states, that Sir Joseph Banks had noticed another some years before in Lincolnshire.[55]
A storm attended with similar effects occurred in this country in 1815, and vented its fury upon the eastern states. It commenced on the 23d of September, between eight and nine o'clock, A. M. with the wind from the east. In about two hours the wind shifted to southeast, and blew a perfect hurricane. The extended devastation which ensued, is still in the recollection of every person. The tides rose from nine to twelve feet higher than ordinary, and in many of the principal cities and towns along the coast of New England, churches, houses, bridges, wharves, and in some instances valuable citizens, were buried in one common ruin. In less than three hours the gale abated, and before sunset there was a perfect calm. Such were the more striking features of this tremendous gale—but other effects were observed more peculiarly interesting to the philosopher. At New-London, Salem, and other places, both on the coast, and several miles in the interior, the air was found to be loaded with salt; and the leaves of many trees appeared, a few hours after the storm, as if they had been scorched. Besides this effect upon vegetables, there were additional evidences of the saline quality of the wind. At Salem and some other places an incrustation of salt was perceived on the windows, and the fruit in several gardens had a perceptible taste of salt on their surface. At New-London it was remarked that the air in the eddies was extremely hot and suffocating.
Other facts of a similar nature might be collected, but these it is presumed are sufficient to characterize the state of the atmosphere during that storm.
Several interesting inquiries arise from the consideration of the foregoing facts.
1. In what way does the salt exist in the atmosphere in these storms? On this point there are two different opinions. The most prevalent is, that it is merely the spray of the sea driven onward by the force of the wind. This opinion has received the sanction of Sir Joseph Banks,[56] and also of Sir Humphry Davy, if we may judge from an incidental expression in his Agricultural Chemistry.[57] Another opinion[58] is, that muriate of soda is continually rising into the atmosphere from the surface of the ocean, and that the air, in all maritime situations, is thus constantly more or less impregnated with salt. The most striking fact in support of this doctrine, (so opposite to the commonly received views on the subject of the evaporation of sea water) is the actual existence of muriate of soda in the rain and snow which fall in the vicinity of the ocean.[59] The experiments of Vogel and Bouillon Lagrange, on the distillation of sea water, are also in favour of the position, that salt may be carried into the air in the ordinary process of evaporation. On distilling salt water they found a considerable quantity of muriate of soda in the receiver.[60]
Admitting the correctness of these experiments, still it is not easy to conceive, how they will account satisfactorily for the large quantities of salt found in the air during the storms under consideration.
Whichever of these solutions may be adopted, it is unquestionably a fact that salt does, in some way or other, exist in the atmosphere in the neighbourhood of the sea.
2. The next object of inquiry is, the influence which this saline air has upon vegetable life. Independently of the facts already stated, there are many others which prove its deleterious agency upon the vegetable creation. Dr. Mitchill informs me, that in some parts of the south side of Long-Island fruit trees do not thrive well, except at a distance of thirty miles from the sea, and even the sturdy oak does not extend its branches towards the ocean.[61] If I am correctly informed, it was with great difficulty, that the trees on our Battery were made to accommodate themselves to a situation so near the salt water. It is also well known, that when plants are taken to sea, they speedily perish, if exposed but a short time to a wind, which is sufficiently strong to turn over the tops of the waves into white caps, as they are called by the sailors.
In order to ascertain positively, whether these effects were to be attributed to the operation of salt, I made a solution of muriate of soda in common rain water; with this I watered for a couple of days the leaves of different plants. In a short time they began to dry up, and in a few days were completely dead.
It appears from Volney, that the Egyptian air is strongly charged with salts. The evidences of it are to be found even at Cairo.[62] It is this property of the air, which this philosophical traveller considers, as one of the causes of the rapid vegetation in that country. He mentions, however, that exotic plants will not thrive there. It is found necessary to renew the seeds of them every year. May not this be occasioned by the saline quality of the air? The native plants are doubtless accustomed to its action, and do not so sensibly feel its injurious effects. And if the Egyptian air is so very penetrating from this very cause, as to produce ophthalmia, may we not rationally conclude, that its influence must be equally injurious to plants not accustomed to it.
Another illustration of the influence of salt on vegetation is to be found in the Dead Sea, or Lake Asphaltites. "In Lake Asphaltites," says Volney, "there is neither animal nor vegetable life. No verdure is to be seen on its banks, nor fish to be found within its waters; but it is not true, that its exhalations are pestiferous, so as to destroy birds flying over it. It is not uncommon to see swallows skimming its surface, and dipping for the water necessary to build their nests. The true cause which deprives it of vegetables and animals is the extreme saltness of the water, which is vastly stronger than that of the sea. The soil around it, equally impregnated with this salt, produces no plants, and the air itself, which becomes loaded with it from evaporation, and which receives also the sulphureous and bituminous vapours, cannot be favourable to vegetation; hence the deadly aspect which reigns around this lake."[63]
3. In what way does the salt operate in producing its deleterious effects on the leaves of vegetables? It is by no means easy to answer this question. It cannot be by shutting up the pores of the leaf, and thus obstructing its perspiration. It is well known that when the surfaces of leaves are covered with oil, they will soon die.[64] But salt water is certainly not sufficiently viscid to act in a similar way.
Nor can it be satisfactorily attributed to the difference of structure between maritime and land plants. There is some difference indeed between many of these, maritime plants being generally covered by a pubescence, of which most land plants are destitute. It is idle however to suppose that the object of this covering is to protect maritime plants from the action of the salt air, as there are many of them which do not possess it. Besides, is it not rational to conclude, from the large quantities of soda which are always found in sea plants, that this saline atmosphere is rather propitious than otherwise to their growth, and that it only proves injurious to plants accustomed to the unadulterated air of the land.
Again, I do not think that it can be explained by supposing, that the salt is absorbed into the plant, and thus acts as a poisonous substance. We know, that in land plants which are cultivated in the neighbourhood of the sea, salt is absorbed through their roots.[65] It must of course circulate with the juices through the whole plant; and yet in these cases the leaves are not destroyed by it.
The most plausible method of explaining it appears to be this: that the salt, by its irritating or corrosive power, destroys the small vessels in the leaf which are necessary for the circulation going on in it during health.
Dr. Darwin has ingeniously shown the analogy between the functions of the leaves of plants, and the lungs of animals. If this be admitted, it will not be difficult to account for the action of salt upon leaves. This substance, when taken into the stomach, proves not merely innocuous, but wholesome; but when accidentally introduced into the lungs, irritation, inflammation, and death are the consequences. So with plants—when admitted into them in combination with their juices, it may be harmless; but when applied to the lungs or leaves, death ensues.
4. I shall devote the remainder of this paper to a few concise observations on the effects of salt, and a saline atmosphere, upon animal life.
Upon the more imperfect animals, such as slugs, worms, toads, &c. it is well known that salt proves speedily destructive of life. It is not my intention to attempt an explanation of this singular fact. But it is remarkable that it should not have been turned to better account in the treatment of those worms, which infest the human body. Although used for that purpose by the common people in Ireland as well as in this country, I believe it has not, until very lately, claimed the attention of the profession, as an anthelmintick. A late English journal[66] contains a notice of some cases which satisfactorily prove its efficacy, when administered with this intention. This fact, in addition to numerous others, strikingly illustrates the advantages which the healing art might derive from a careful observation of the phenomena daily developed by the collateral sciences.
In cases of hæmoptysis and hæmatemesis, common salt has been used with decided success. The public is indebted to Dr. Rush, for the introduction of this remedy into general practice.
Dr. Hosack informs me, that he has found sea air extremely salutary in remittent fever, cholera infantum, and dyspepsia.
Among the deleterious effects caused by a saline atmosphere, may be mentioned the ophthalmia of Egypt. This disease is so common there, "that out of a hundred persons," says Volney, "I have met while walking the streets of Cairo, twenty have been quite blind, ten wanting an eye, and twenty others have had their eyes red, purulent, or blemished."[67] Throughout the Delta, and at Cairo, this complaint is more prevalent than in any other part of Egypt. In Syria it is also common, although less so than in Egypt, but it is only met with on the sea-coast. The reasoning of Volney on this subject, is decisive of the position, that the prevalence of this complaint, in these regions, is owing to their proximity to the ocean. In confirmation, he states that he has himself experienced the irritating effects of the air of the Delta upon the organ of vision.[68]
In those cases of scurvy which occur in long voyages, the saline nature of the atmosphere co-operates very powerfully with salt provisions and bad water, in producing that general vitiation of the system which characterizes this disorder.
Of all diseases, however, those of the lungs appear to be most affected by a saline air. I have known a lady of this city who had been afflicted for many years with asthma, to be essentially benefited by a voyage across the Atlantic. Another case has fallen under my observation, of a lady troubled with asthma, being much relieved by removing from the interior to this city. What proves beyond a doubt that her relief is owing to the air she breathes, is, that whenever she takes a jaunt into the country, she is sure to suffer a paroxysm of her old complaint.
Pulmonary consumption certainly prevails more on the sea-coast, than in the interior. In all our sea-port towns, it is this disorder which so frightfully augments the catalogue of our bills of mortality. According to Dr. Rush, "in Salem, in the state of Massachusetts, which is situated near the sea, and exposed, during many months of the year, to a moist east wind, there died in the year 1799, 160 persons; fifty-three of whom died of the consumption."[69] In Philadelphia, which is more remote from the sea, the deaths from consumption are much less numerous than in New-York, or the other cities immediately on the coast. In Great Britain, which is exposed to the sea on all sides, it is calculated that about 55,000 die annually from this disease.
Such are some of the facts on this subject; but the conclusion does not appear to be warranted, that these pulmonary affections arise from the irritating quality of the air. In Holland, the West Indies, as well as in other countries and islands, exposed to the sea air, consumption is of rare occurrence. In Syria, Volney even states that the air of the coast is particularly favourable to those labouring under this malady. Accordingly they are in the habit of sending such patients from Aleppo to Latakia, or Saide, where they may enjoy the benefit of sea air.[70]
Again, we know that many persons suffering from this affection, have been completely cured by a voyage, after all the resources of medicine had been exhausted upon them in vain.
It is evident then, that a pure sea air is not detrimental in cases of consumption. Dr. Rush, with his usual ingenuity, explains the prevalence of this complaint in our sea-ports, by attributing it to the mixture of land and sea air; and in confirmation observes, that "those situations which are in the neighbourhood of bays and rivers, where the fresh and salt waters mix their streams together, are more unfavourable to consumptive patients than the seashore, and therefore should be more carefully avoided by them in exchanging city for country air."[71]
Independently, however, of these causes, I think the frequent and sudden vicissitudes of temperature, which we suffer on the coast, are alone sufficient to account for the prevalence of catarrhal and pneumonic affections, which most commonly are the precursors of consumption.
I trust the foregoing observations have not been considered too medical to comport with the objects of this Society. Natural history is only useful in its practical applications; and if it can be shown to throw any light upon an art, which contributes so much to the comfort and happiness of man, we have established one of the strongest considerations, which can recommend it to general patronage and investigation. Physicians ought in an especial manner to set a high value upon the researches of naturalists. The aid they have already given is sufficient to entitle them to the lasting gratitude of our profession. It was one of the merits of that illustrious physician of our own time and country, Dr. Rush, that he seized with avidity every fact, from whatever quarter it might be drawn, to elucidate his favourite science. If ever medicine shall attain to the elevation of a truly philosophical science, it must be accomplished, in part at least, by imitating his example, and by developing the infinite and diversified associations which exist between it and the other sciences.