Chapter XVI: Front Matter (16)

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.

ART. XIV. _Thoughts on Atmospheric Dust. By_ C. S. RAFINESQUE, _Esq._

1. "When we find the ruins of ancient cities buried under ground; when the plough uncovers the front of palaces and the summit of old temples, we are astonished: but we seldom reflect why they are hidden in the earth. A sort of imperceptible dust falls at all times from the atmosphere, and it has covered them during ages."

2. These are the words of the worthy and eloquent philosopher VIREY, in his article Nature, Vol. XV. p. 373, of the French Dictionary of Natural History. Even before reading them I had observed the same phenomenon, and I have since studied their effects in various places. I could quote one thousand instances of the extensive and multifarious operations of this meteoric dust: but I mean to give the results merely of those that fall daily under notice, and are yet totally neglected; wishing to draw on them the attention of chemists, philosophers, and geologists.

3. Whenever the sun shines in a dark room, its beams display a crowd of lucid dusty molecules of various shapes, which were before invisible as the air in which they swim, but did exist nevertheless. These form the atmospheric dust; existing every where in the lower strata of our atmosphere. I have observed it on the top of the highest mountains, on Mount Etna, in Sicily, on the Alps, on the Alleghany and Catskill mountains in America, &c. and on the ocean.

4. It deserves to be considered under many views: which are its invisibility, its shape and size, its formation and origin, its motion, its deposition and accumulation, its composition, its uses, and its properties.

5. This dust is invisible, owing to the tenuity of its particles, but they become visible in the following instances; when the sun shines on them, since they reflect the light, when their size is increased, and when they are accumulated any where.

6. The size of the particles is very unequal, and their shape dissimilar; the greatest portion are exceedingly small, similar to a whitish or grayish spark, without any determinable or perceptible shape; the larger particles are commonly lamellar or flattened, but with an irregular margin, and the largest appear to be lengthened or filiform; the gray colour prevails. Other shapes are now and then perceptible with the microscope.

7. Among the properties of atmospheric dust are those of being soft, as light as atmospheric air, of reflecting the rays received directly from the sun, of possessing a kind of peculiar electricity, which gives it a tendency to accumulate on some bodies more readily than on some others, and of forming an earthy sediment, which does not become effervescent with acids.

8. This dust is either constantly or periodically formed, but chemically in the atmosphere like snow, hail, meteoric stones, honey-dew, earthy rains, &c. by the combination of gaseous and elementary particles dissolved in the air. Its analysis has never been attempted by chemists; but the earthy sediment which is the result of its accumulated deposition, proves that it is a compound of earthy particles in a peculiar state of aggregation, and in which alumine appears to preponderate, rather than calcareous or silicious earths or oxides.

9. Its motion in calm weather, or in a quiet room, is very slow; the particles appear to float in the air in all directions, some rising, some falling, and many swimming horizontally, or forming a variety of curved lines; what is most singular, is that no two particles appear to have exactly the same direction; yet after awhile the greatest proportion fall down obliquely, somewhat in the same manner as a light snow in a calm day. When a current of air is created naturally or artificially in the open air or in a room, you perceive at once an increased velocity in their motion; they move with rapidity in all directions; but when a strong current or wind prevails, they are carried with it in a stream, preserving however, as yet, their irregular up and down motion.

10. Its formation is sometimes very rapid, and its accumulation very thick in the lower strata of our atmosphere, but the intensity is variable. Whenever rain or snow falls, this dust is precipitated on the ground by it, whence arises the purity of the air after rain and snow; but a small share is still left, or soon after formed. In common weather it deposits itself on the ground by slow degrees, and the same in closed rooms. It forms then the dust of our floors, the mould of our roofs, and ultimately the surface of our soil, unless driven by winds from one place to another.

11. I have measured its accumulation in a quiet room, and have found it variable from one-fourth of an inch to one inch in the course of one year; but it was then in a pulverulent fleecy state, and might be reduced by compression to one-third of its height, making the average of yearly deposit about one-sixth of an inch. In the open air this quantity must be still more variable, owing to the quantities carried by the winds and waters to the plains, valleys, rivers, the sea, &c. or accumulated in closed places or against walls, houses, &c. I calculate, however, that upon an average, from six to twelve inches are accumulated over the ground in one hundred years, where it mixes with the soil and organic exuviæ, to form the common mould.

12. The uses of this chronic meteor are many and obvious. It serves to create mould over rocks, to increase their decomposition, to add to our cultivable soil, to amalgamate the alluvial and organic deposits, to fertilize sandy and unfruitful tracts in the course of time, to administer to vegetable life, &c. It does not appear that it has any bad influence on men and animals breathing it along with air, unless it should be accumulated in a very intense degree.

13. At Segesta, in Sicily, are to be seen the ruins of an ancient temple; the steps, which surround it on all sides below the pillars, are built on a rock, on the top of a hill detached from any other higher ground. Yet now all the steps and the base of the pillars are under the ground, which has accumulated from this dust and the decay of plants (not trees) to which it has afforded food. There are from five to eight feet from the rock to the surface of this new soil, which has chemically combined in a variety of hardness. This soil has arisen there in about 2000 years, notwithstanding the washings of rain. I quote this as a remarkable instance of the increase of soil by aerial deposits, among many which have fallen under my personal examination.

14. It is commonly believed that the dust of our rooms is produced by the fragments of decomposed vestments, beddings, furnitures, &c.; this cause increases it, and produces a different dust, which mixes with the atmospheric dust; but it is very far from producing it.

15. The dust of the open air is ascribed to that raised from roads and fields, by the pulverization of their surface; but this secondary and visible dust is only a consequence of the first. From whence could arise the dust observed by the means of the sunbeams in a dark corner, in winter, when the ground is frozen, or when it is wet and muddy, or at sea, or on the top of rocky mountains?

16. It is therefore a matter of fact, worth taking into consideration by geologists, that the air still deposits a quantity of dust, which must have been much greater in former periods. Just the same as the sea deposits still a quantity of earthy and saline particles dissolved in it, and which were superabundant at the period when the rocky strata were formed on its bottom. Water being more compact, deposits rocks. Air, which is less dense, deposits a pulverulent matter!

ART. XV. _On the Effect of Vapour on Flame. By_ J. F. DANA, _Chemical Assistant in Harvard University, and Lecturer on Chemistry and Pharmacy in Dartmouth College_.

_Cambridge, Mass. February 5, 1819._

_To Professor Silliman._

DEAR SIR,

About a year since I made some experiments on the effect of steam on ignited bodies, with a view to learn the theory of the action of the "American water-burner." These experiments were published in an anonymous paper in the North American Review, and have been published in London, without an acknowledgment of their source.

The effect of them concerning bodies is peculiar, and it probably admits of more extensive application to the arts than in the above named instrument alone.

When a jet of steam, issuing from a small aperture, is thrown on burning charcoal, the brightness is increased, if the coal be held at the distance of four or five inches from the pipe through which the steam passes; but if the coal be held nearer it is extinguished, a circular black spot first appears where the steam is thrown on it. The steam in this case does not appear to be decomposed, and the increased brightness of the coal depends probably on a current of atmospheric air, occasioned by the steam. But when a jet of steam, instead of being thrown on a single coal, is made to pass into a charcoal fire, the vividness of the combustion is increased, and the low attenuated flame of coal is enlarged.

When the wick of a common oil lamp is raised, so as to give off large columns of smoke, and a jet of steam is thrown into it, the brightness of the flame is increased, and no smoke is thrown off.

When spirits of turpentine is made to burn on a wick, the light produced is dull and reddish, and a large quantity of thick smoke is given off; but when a jet of steam is thrown into this flame, its brightness is much increased; and when the experiment is carefully performed, the smoke entirely disappears.

When the vapour of spirits of turpentine is made to issue from a small orifice, and inflamed, it burns, and throws off large quantities of smoke; but when a jet of steam is made to unite with the vapour, the smoke entirely disappears. When vapour of spirits of turpentine and of water are made to issue together from the same orifice, and inflamed, no smoke appears. Hence its disappearing, in the above experiment, cannot be supposed to depend on a current of atmospheric air.

When a jet of steam is thrown into the flame of a spirit of wine lamp, or into flames which evolve no smoke or carbonaceous matter, the same effect is produced as by a current of air.

It appears, from these experiments, that in all flames which evolve smoke, steam produces an increased brightness, and a more perfect combustion.

Now, with a very simple apparatus, steam might be introduced into the flames of street lamps, and that kind of lamp which is used in butchers' shops in London, and in all flames which evolve much smoke. The advantage of such an arrangement would be a more perfect combustion, and a greater quantity of light from the same materials. The flame of the lamps, to which steam is applied, might be made to keep the water boiling which supplies the steam.

I hope the above may not be altogether uninteresting and useless to the readers of your Journal.

Very respectfully, your obedient servant,

J. F. DANA.

ART. XVI. _Analysis of the Harrodsburg Salts, by_ EDWARD D. SMITH, M. D. _Professor of Chemistry and Mineralogy in the South-Carolina College_.

More than a year since I received a quantity of a white earthy substance, which was said to be obtained by the evaporation of certain mineral waters at Harrodsburg, Kentucky, and there vended at a considerable price, under the name of Epsom salts. The respectable character who presented this powder to me, requested that I would make an analysis of it; but I had not sufficient leisure until lately, to pay the requisite attention to this subject. The results of my examinations are now submitted to the public eye.

The external qualities of this substance are as follow: small white lumps, hard to the touch, but dry and easily yielding to pressure, somewhat gritty to the teeth, and imparting an earthy and saline taste to the tongue.

1. 120 grains of the powder were put into about a half ounce of alcohol, digested for six hours, then, washed with more alcohol, filtered and carefully dried.

2. On weighing the dry powder, the loss appeared to be but one grain, so that it contains very little of any substance which is soluble in alcohol.

3. 115 grains (four grains having been lost in the transfer from the filter) were collected and put into rather more than eight times their weight of cold distilled water, and digested for two hours.

4. This watery solution was then filtered, and on weighing, the residue appeared to be 48 grains, so that 67 grains must have been dissolved.

5. 10 grains of the insoluble residue (4) were put into a flask, with 10 ounces of distilled water, and boiled for 1 hour.

6. A small portion of this solution, on being tested with nitrate of barytes, gave a copious white precipitate, with oxalic acid, a white cloud; with ammonia, a slight white cloud; with muriatic acid, a slight bluish tinge. From these tests it was inferred that sulphate of lime was present, with perhaps a slight trace of muriate of lime.

7. The remainder of this solution was filtered, and on weighing the dried residuum, the loss appeared to be 2 grains, so that sulphate of lime probably constitutes nearly ⅕ of the insoluble residence (48 grains. 4.)

8. The watery solution, (4) which was supposed to contain 67 grains, was evaporated, and left a residue that weighed but 34 grains, so that 33 grains must have disappeared in the process.

9. Some of this residue dissolved in distilled water, was tested with carbonate of soda, forming an immediate white cloud; with nitrate of barytes, the same; with ammonia, the same; but with oxalate of ammonia, it did not form any cloud until it had stood some time, and then it was slight. From these tests it was inferred that sulphate of magnesia was present.

10. A portion of the dried residuum (7) was treated with diluted muriatic acid, which dissolved nearly the whole of it, with considerable effervescence. The new compound, on examination, proved to be muriate of lime; so that it may be concluded the residuum (7) was principally carbonate of lime.

On considering the results of the preceding experiments, it will appear that more than one half of the substances submitted to analysis, was easily soluble in water, and from the chemical tests used, that it was composed principally of sulphate of magnesia, (Epsom salt) with perhaps a small portion of muriate of lime or magnesia, that of the remainder, about ⅕ was sulphate of lime, and difficultly soluble in water; and that the rest was perfectly insoluble in water, and consisted principally of carbonate of lime.

There can be no doubt then, that the Harrodsburg salt, in its present state, is very improperly prepared, containing in its composition a large proportion of matter, that is not only inert, but which may produce considerable inconvenience and injury in the stomach and bowels, from its ponderous nature and tendency to form mechanical obstructions. Perhaps the occurrence of such injury may not be frequent, from the circumstance of a large portion of the salt being so insoluble; but admitting this to be the fact, there is a manifest impropriety in offering to the public, as medicine, an article which cannot be used as such. Probably the proprietors of this manufactory are not aware of the real nature of the case, and of the facility with which, by a little additional trouble, they could separate the useful and valuable material, from that which is at least useless, and which might also be pernicious.

_South-Carolina College, March, 1819._

ART. XVII. _Additional Notice of the Tungsten and Tellurium, mentioned in our last Number._