Chapter III: Book 5: , chap. 2, Page 403—Account of a new compound Microscope for (2)

For analogous reasons, its effect in the production of disease is increased by concentration or condensation; and such a state of things takes place in narrow and confined valleys, or in places surrounded by woods, or in woods themselves; in any situation, in short, where the poison is produced, and is so sheltered from winds that ventilation becomes difficult. And if it is probable that this is one chief reason of the peculiarly insalubrious nature of woods and jungles in hot climates, so is it an universal remark in Italy, that the short valleys in which the air cannot circulate are among the most pestilential spots. And if this explains, also, in some measure, the bad effects of calm weather, so does it account for the unusually pestiferous nature of rivers and lakes confined within wood, as are those of the tropical climates, and as there are many also in different parts of Europe. That we ourselves are not exempt from these additional causes of the influence of malaria, would be easily shown by many references, were it not for the reason which has caused me to exclude them.

It is another important question for practice, how far and in what manner malaria can be conveyed by the winds to places where it is not produced, so as to act in exciting disease. That it is conveyed to certain distances by winds is amply proved by an abundant experience, and I may first detail a few of the most useful particulars as to this fact. In Italy and Greece, it is observed, that where long valleys terminate on sea shores, on which the exits of the rivers are swampy, it is an [p045] effect of the sea breeze, by crossing such marshy ground, to convey the malaria up into the interior country, to considerable distances, and to places which are in themselves not insalubrious. Thus, also, does such a breeze, especially when it is a warm wind, convey the poison up the acclivities of hills, even to a considerable range of distance or elevation; a process facilitated by the natural tendency of such winds to ascend. And as a striking proof of this migration of malaria, it appears from Capt. Smyth’s statistical account of the insalubrious villages in Sicily, that out of more than seventy, about one-half are not seated near or on lands producing this substance, but on acclivities, at varying distances—thus receiving it through migration. The same is remarked by Montfalcon of many towns in France; while in some, the place at a distance is even more unhealthy than that which is immediately situated in the marsh itself: and in our own country, this is equally said to be true of the backwater at Weymouth, and of the marshes of St. Blasey in Cornwall, acting more powerfully at some distance than in the immediate spot.

With respect to the absolute distance to which the malaria can be conveyed, it is yet an obscure circumstance, or at least the maximum has not been fixed; but it is at least ascertained that the convent of Camaldoli receives it from the Lake Agnano, at a distance of three miles; while from certain naval reports, a distance of five miles has been proved to permit its transmission,—and from an evidence that cannot be doubted, inasmuch as it was the sudden breaking out of fever in a healthy ship, anchored at that distance from the shore, on the coming off of the land wind, attended by its peculiar and well-known smell.

These facts are satisfactory thus far, and it would be abundantly easy to add to them; but there is reason to suspect that it can be conveyed to far greater distances, in certain favourable circumstances: those reasons, in the first place, being derived from certain meteorological analogies and considerations, and in the next confirmed by experience. It is notorious that the ague appears on our eastern coasts with the first east winds of spring; and while this circumstance is most common on those of England, as for example, in Kent, Essex, Norfolk, [p046] Suffolk, and Lincolnshire, it is not thus limited, since it is known to happen further north, and even in Scotland, where malaria is not indigenous to the soil. It is very true that if we take any inland position in the places thus noted, the natural solution is, that the malaria is generated in the very soil itself of England, and merely propagated, perhaps even to very moderate distances, through those winds. But the occurrence of disease cannot be explained thus, when the place in question is so situated that there is no land to the eastward, or when the breeze is, most literally and rigidly, a sea breeze; while, when ague thus occurs on the east coast of Scotland, where it is not produced by the soil, it must be imported by the east wind.

These are the facts; while as malaria is not produced by the sea itself in any known circumstance, though a vegetating sea beach may give rise to it, we must seek the cause in lands far distant, and consider this as a case of propagation of the poison from the shores of Holland; and those shores are unquestionably competent to that effect: so that the only question that remains, the fact being admitted, is, whether, _à priori_, or theoretically, such a view is probable, or whether it is consistent with those physical principles that are concerned in the propagation of malaria.

I am aware that such a view will excite the incredulity of those who have not attended to this subject; though it appears to me that it comprises nothing averse to our knowledge of the philosophical circumstances concerned. In the first place, let us remark that the east wind, and particularly the east winds of spring, are notorious for their moisture, and that a moist air is the best conductor of malaria, as moisture in the air, under the form of evening mists, or in other modes, appears even to be its proper vehicle, or residence, if I may use such a term; and though I have not as yet separated the case of a fog, I may now remark, that the effect in question, or the production of agues by fogs arriving from the sea, is even more notorious than their generation by an ordinary clear wind. So notorious and popular, indeed, is this fact, that the fog itself is deemed the source of the disease, as the east wind under any form is, in other circumstances; while I hope it will even now appear, [p047] that the real cause lies in the malaria transported or conveyed by those winds or fogs, and of which they are the true and best repository and vehicle.

And these are the reasons for thinking that the malaria, with the wind, may be transported to a distance as great as that which the present view requires; most easily perhaps in a fog, but without difficulty even in a clear wind. It is remarkable that the east wind, as it is the most persevering, is that one also which preserves the most steady horizontal and linear course. I have also shown, in a former work, that it is a property of winds to travel in distinct lines through a tranquil atmosphere, and often in streams of a very limited breadth; that opposing streams will also move, in absolute contact; and that even rapid streams of wind will cross each other’s courses without difficulty. This proves that, in any such stream, there is a principle of self-preservation or integrity, and renders it probable that the several portions retain the same relative places to each other, at any distance, during the career of the whole; and there is a proof of this afforded in the fact of those columns or streams of insects which are brought over by such winds, and very frequently from those very countries, or from Holland and Flanders, in the most regular order, or without disturbance or dispersion.

Hence it may be argued, that if a malaria, generated any where and conveyed by the winds, can be transported to a distance of three miles, as has been proved, there is no reason why it should not travel much farther, or to any distance that can be assumed: and if this be true of a clear wind, the case of a fog is even a much stronger one; since there is little reason to doubt that the individual parts of such fog, in any assumed mass, will retain their relative places to each other, as perfectly after a journey of any given number of miles, as they did at the point of production; and if a portion of malaria has been united to a portion of fog, in the marsh which produced both, or whence both have come, there is every apparent reason why it should be found in that same portion at any farther or assumed distance, because there is no cause for either its dispersion or its decomposition.

A fog is a cloud, simply; and it is notorious that a single [p048] cloud, and often of very small dimensions, will remain at rest in the atmosphere, or travel very many miles without the loss of its integrity; however we may imagine it assailed by the various meteorological causes of destruction, as well as by mechanical violence. This in itself proves the consistency with which a current of wind preserves the relative positions of its integral parts; because it is plain that a disturbance among these must disturb or destroy the cloud which, in reality, forms a portion of that current, as a gaseous body: and since that cloud is a mist, since it might have been the very evening mist embodying a malaria, and since it is its real vehicle and repository, it is plain that had it, or any individual cloud, contained such a portion of malaria, it must have had the power of transmitting that, and would actually have transported it to any distance to which itself might travel. Thus, it is evident, may a fog, generated in Holland, carry without difficulty to the limits of its range, or to the coast of England, that malaria which became entangled with it at its birth-place or in its passage; and thus, I have little doubt, is the fact of those agues explained, and this transportation to such distances established.

I cannot, at least, conceive any demonstration as to facts of this nature more convincing, nor anything wanting to the proof; while I may proceed to make some remarks on the east wind, and on fogs, simply, because they concern this question.

The proof that it is a malaria in the fog, and not the fog itself, which is the cause of disease, is evinced by the following fact; while it ought surely to be unnecessary to say, that if fog alone could produce such fever, water itself must be the poison: since a fog is a cloud, and its constituents, when pure, are only atmospheric air and water. No intermittents are ever produced on the western or northern shores by the sea fogs, and for the plain reason, that there is no land whence they arrive. The clouds of mountainous regions do not produce fevers, though these also are fogs; and what forms a most absolute proof of this is, that in Flanders, it is the fogs which come with a southwest wind, or the southerly winds themselves, which transport and propagate malaria and disease; while; as soon as the winds shift, and blow from the sea, the fevers [p049] disappear, though those particular winds are so charged with fog, as to darken the whole country for days: and it will be found an invariable rule all over the world, that when a fog is the apparent cause of disease, or when an east wind is such, it is because these have been generated in a land of marshes, or have traversed one; and that, under other circumstances, or where no pernicious land lies in the way, they are as innocent as any other fogs and winds, and that the hazard and the suffering will arise from those, be they whatever they may, which traverse pestilential lands.

But I must defer this particular and interesting subject to another occasion, lest I make this article too long; and proceed to examine some other circumstances connected with the transportation of malaria.

First, however, I must notice one fact as to this transportation from Holland, partly because it is a necessary fact in the history of malaria, and partly because it might be used as an argument against the view which I have just given. The east winds of autumn are not supposed to bring remittents, as those of spring bring agues, though I cannot assert that this is absolutely true. Being assumed, the solution is easy. If the winds of this nature in spring, are notedly moist, and thus vehicles of malaria, the case is exactly the reverse with the east winds of summer and autumn; or as the east wind may be the most moist of winds, so may it be the most dry; while it is a consequence of its extreme dryness, in fact, that it is always the very cause of our burning summers. This is the history of our last summers, and it is invariable, whether as it relates to seasons or single days; and it is plainly owing to its permitting the more ready transmission of the sun’s rays. That it is the very harmattan of Africa, it is almost unnecessary to say; and as dry wind is not a conductor of malaria, as that poison is in fact decomposed or destroyed in these circumstances, daily and invariably, it is easy to see why the remittents of Holland should not be transported, like its intermittents, though even this may possibly happen under particular circumstances.

To proceed; and to the next remarkable facts connected with the propagation of malaria.—The most singular of these is its limitation, or that yet unexplained property by which it is [p050] determined in a particular direction, or confined to a particular spot, while it is a piece of knowledge of some practical value. There is an appearance of incredibility about many of these facts, and, accordingly, they have not only been disbelieved but ridiculed, although nothing in the whole history of this substance is better established.

With respect to direction, in the first place, it is remarked in Italy, currently, that this poison will enter the lower stories of houses, particularly with open windows, when the next above escape; and hence, in many places, no one ventures to sleep on ground floors: and the truth of this was confirmed in the barracks at Jamaica by Dr. Hunter; as the cases of fever occurring among the men in the lower rooms much exceeded those which happened in the upper ones. But I am also informed, that in some places in Norfolk this peculiarity is reversed; or that there are houses where it is remarked that the ground-floors are safe, while no one can sleep in the upper stories without hazard.

That malaria may in some manner be attached to the soil is also well known by its effects, and especially in Italy. There it is remarked that it is extremely hazardous to cut down certain bushy plants which appear to entangle it, and that fevers are a frequent consequence of such carelessness. Thus, also, does fever seize on the labourers who may incautiously sit down on the ground, while they would escape in the erect posture; being thus, indeed, sometimes suddenly struck with apoplexy, which is one of the effects of this poison, or even with death.

It has similarly been observed that it is often retained in the shelter of drains, or in the ditches of fortifications; whence frequent fevers among the sentries on particular guards, when the other soldiers escape. And thus was it even proved at Malta, that it was transported from the sea-shore, and thus lodged in a dry ditch of the works at Valetta; all these facts being possibly to be explained, by supposing it possessed of a greater specific gravity than the atmosphere, or else attached to vapour thus weighty, exhibiting effects analogous to those which carbonic acid displays in the Solfatara.

But the circumstance most difficult of explanation is, that in Rome, and numerous places in Italy, and even where it is [p051] transported from a distance by the winds, not generated on the spot, it is found, perennially, and through the whole course of successive years, to occupy certain places, and to avoid, as constantly, others quite near, and, as far as the eye can judge, equally exposed, and in all respects similar. Thus, one side of a small garden, one side of a street, or one house, will be for ever exposed to disease, or uninhabitable, when, at a few feet or yards distant, the very same places are as constantly free of danger: and thus it was found at the village of Faro, in Sicily, that all the troops of our army quartered on one side of the single street which formed it, were affected by fevers, and suffered great mortality, while those on the other remained in health.

But the most remarkable case of this nature known to me, is a domestic one, and which rests on the testimony of thousands of persons, or of the whole country, however incredible it may appear. It is, that between Chatham and Brighton, including every town and single house, and Sittingbourne among the rest, the ague affects the left hand side of the turnpike road, or the northern side, and does not touch the right side, though the road itself forms the only line of separation.

We cannot as yet conjecture the cause of this very singular circumstance or property, at least in cases of this nature; though, under certain events of this kind, there are some facts in meteorology that may offer a solution. These are the notorious ones, that a hoar frost, or a dew, will sometimes be found most accurately limited, both vertically and horizontally, by a definite line; stopping, for example, at a particular hedge, and reaching to a certain altitude on a tree: but for the other cases, we must yet wait for a period of more accurate knowledge as to this singular substance.

There is now one circumstance of importance, relating to the destruction or decomposition of malaria, which must not be passed over, from the interest of the facts depending on it: this is, that its propagation is checked by the streets of a crowded town, and apparently owing to this very cause, decomposition. Thus it is observed, that the fever never appears in the Judaicum of Rome, and, similarly, that the crowded streets and the poor people escape, when the opulent houses and open [p052] streets are attacked; and hence the Villa Borghese, among many other palaces and opulent houses in Rome, has been abandoned, while such desertion, being limited exclusively to houses where the air is most open and free, naturally excites wonder: the cause, however, is now plain; and thus it now appears why it was that the Penitentiary in Westminster suffered formerly from dysentery, originating in this cause, when no such disease appeared among the neighbouring inhabitants.

And if this fact is of value as it may relate to the erection of open streets in any place of this nature, it is most important to point out what has been the continuous effect at Rome, as the ultimate consequences threaten to be extremely serious.

It appears that from cutting down some forests which many years ago occupied the declivities of the hills to the southward of Rome, the malaria was let in upon that city from the Pontine marshes; and, further, that the extirpation of a similar wood to the eastward had let in the same poison upon another quarter. Thus it has been found to enter the city through the Porta del Popolo, while, for many years past, it has been gradually extending its influence through the streets; leading annually and successively to the abandonment of many houses and palaces, and still annually increasing and extending its ravages; so as, at length, as I understand, to have even become sensible at the Vatican. And the lines which it follows are distinctly traced out by the inhabitants; while, as I have already said, it is only the houses of the opulent which suffer, further than as the abandonment of these may also influence the inferior ones in their neighbourhood.

Whatever the original cause may be, and however the direction, abstractedly, may be regulated by the winds and the forms of the streets, or by local and fixed circumstances, it is plain that the annual extension is the consequence of desertion, and that as the inhabitants retire from before it, it acquires the means of making a new step and a further progress; because thus they withdraw those fires and smoke, or whatever else it be, dependent on human crowds, which decomposes and destroys this substance. And hence it must follow, that as Rome shall become still further abandoned and depopulated, from want of industry, or from political feebleness [p053] added to this cause, the effects must be expected to increase in a sort of geometrical ratio; almost leading to the fear that the whole city itself may, in time, fall a victim to it, or become abandoned to the wolves and mosquitoes.

If I dare not inquire more minutely into the remaining circumstances connected with the propagation of malaria, lest I should extend this article to an inconvenient length, it is necessary now to offer some remarks on prevention, and especially as it relates to this circumstance—the propagation of the poison; since the rules for prevention, as far as this relates to production, may be deduced from what was said in a former paper on this subject, and relate chiefly to the drainage of lands, and to other practices, more or less obvious, which a little reflection will, without much difficulty, deduce from what was there said.

It is plain, in the first place, that as far as the winds are concerned, it is by opposing obstacles to their course that we must attempt to counteract or divert their influence; and that, in this case, it is through the use of trees alone that we possess any power. Thus reversely, as in the case just stated, the cutting down of trees and forests has often been a serious cause of diseases in certain countries, by admitting a malaria to particular spots; though it is easy to see that where any given spot suffers from malaria, through condensation or confinement, the clearing away of these would be the remedy, by attaining a free ventilation. To detail the particular modes in which remedies may be applied through this species of aid, is obviously unnecessary, and not easy, as it must depend on local circumstances, differing for each place; but I may remark, as an example in illustration of my meaning, that where, as in many of the narrow and prolonged valleys of Greece, the sea shore is a marsh, the remedy would be to plant a screen of trees beyond it, and thus to prevent the sea winds from passing into the interior. And thus did the ancient Romans compel the planting of trees on the shores of Latium, to check the current from the Pontine marshes; rendering groves sacred, under heavy penalties, and enacting other laws with the same intentions.

With respect to such temporary precautions in these cases [p054] as may concern armies in the field, or in camps, it is plain that they will depend on attention to the courses and seasons of the winds; while it would be abundantly easy to accumulate, from the histories of campaigns, the most fearful examples of mortality produced by neglect of these and similar precautions, and even down to almost the very date at which I am writing: and there can be no hesitation in saying, that an intimate and accurate knowledge of every thing which concerns the production and propagation of malaria, forms a most important branch in that information necessary to a soldier, and above all to the quarter-master-general’s department and the medical staff: while, did I dare to record but a very small portion of the mortality experienced, not only in our own armies, but in those of Europe at large, during even the last war, from ignorance or neglect on this subject, it would, I believe, be found that it almost equalled the mortality produced by the actual collision of war itself. Walcheren will not soon be forgotten; if we have ceased to think of our mortal Havannah expedition; and if a French army at Naples was diminished by twenty thousand men, out of twenty-four, in four days, from this cause; if Orloff lost nearly his entire army in Paros; if Hungary has more than once destroyed ten times the number of men by fever that it did by the sword,—these are but trifles in the mass of reasons for saying, that no subject can well be more important, and no knowledge much more necessary to the commander of an army.

Some other points relating to prevention may deserve a few words of notice, before I pass from this subject; if here, also, I must be brief. Not to repeat the cautions founded on what relates to the power of evening and morning, it has been asserted that the use of a gauze veil will prevent the effect of malaria; and it is not improbable that the air accumulated within that, may have the power of decomposing the poison: it is an opinion, at least, which is universal among the people in Malta, and very general in Spain and Portugal. It is also found that fires and smoke are useful, and especially on military service; the experiment having been tried on a very large scale by Napoleon before Mantua, and on a smaller one in Africa, with the most perfect success. With respect to [p055] personal precautions, it is universally recommended to use wine and a good diet, and especially never to leave the house in the evening in situations peculiarly insalubrious, without the previous use of wine or spirits; whence the universal practice of Holland in this respect. Thus, also, narcotics prevent its influence; whence the wide use of tobacco, of which the salutary effects appear to be most amply established.

As to the tropical countries, there is here also one important remark, which, from the great neglect of the fact, and its ruinous consequences, appear particularly to demand a statement in this place. It is the universal experience of the inhabitants, that the attack of malaria, or the production of fevers, is aided by the use of a full or animal diet; by the use of some particular articles of food, such as butter; by excess in eating, generally; and, above all, by eating in the heat of the day. This is not merely well known to the negroes, but the fact is distinctly stated to travellers, and the caution urged, however often it has been neglected, and especially by our own countrymen. Of this, in particular, Major Denham is a strong testimony; while he attributes his own exclusive preservation to his having rigidly followed the recommendations of the natives, which were always urged with the greatest earnestness. And if we examine the causes of death, in most cases, of our African travellers especially, I think there will be strong reasons for believing that their lives have often been sacrificed to this very negligence or obstinacy; while it is most evident that Niebuhr’s party, in particular, owed the loss of their lives to what may be safely called gluttony: and it is to be suspected that this will also explain the loss of Captain Tuckey’s party; while, with respect to nations, it has long been known that the English, the Dutch, and the northern voracious people in general, who habitually indulge themselves in the customs of their original country as tropical colonists, have always been greater sufferers from the effects of those climates than the French and the Spaniards, and apparently from this very difference. And there seems little doubt, generally, that the vegetable diet of Africa and Hindostan is the best security against the evil influence of those climates, and that the chief sufferings of our [p056] own colonists arise from transferring to those situations their ancient habits of full and free living.

As I must not prolong this subject much further, I shall now pass to a few remarks, but very brief ones, on the geography of malaria as it relates to those parts of the continent of Europe most frequented by English travellers; not daring to take room for actual and useful information on that head, but wishing to point out merely the importance of such geographical knowledge to those persons, on account of the hazards which they so universally incur from that ignorance or neglect, and of the great mass of suffering, and also of mortality, which has been the lot of persons who had resorted to those climates as travellers, or migrating residents, from various motives, and not unfrequently with views to health. How often health has been lost where it was sought, will be but too apparent to any one who has chanced to possess an extensive acquaintance of this nature.

Of Italy I can but afford to say generally, that except at a very few points where the Alps or Apennines reach the sea, the whole of its shores are pestilential, and often to such a degree as to lead to their entire desertion, more frequently to their abandonment in summer. And to avoid wet lands, or low lands, is not always a sufficient precaution; since the most pestilential parts of the maremma of Tuscany are dry, and since the annual mortality of Sienna from fevers, even without epidemics, is one in ten. In the north of Italy, the great plain is similarly insalubrious; though the more unhealthy district does not commence until we arrive at Mantua, extending thence to the sea. Of the Mediterranean islands, I can only afford room to say, that the same rule holds good as to the sea coasts, while the entire of Greece in the same circumstances is similarly unhealthy, and subject to autumnal fevers in as great a degree as the worst parts of Italy. The same is true of Spain and Portugal, and the same rule also will be a guide; namely, that malaria is to be expected in all the flat grounds, even when under cultivation, and at all the exits of rivers on the sea, even though no marshes should be present: and if I were desirous to name any tract of land in Spain peculiarly [p057] insalubrious, it would be the province of Valencia; while Carthagena is almost invariably fatal even to those who, as labourers, are compelled to resort to it for the needful work of its port, even during a few days.

Of France, little as it has hitherto been suspected by those who, associating the term malaria with Italy, have been accustomed to consider it as peculiar to that country, it would scarcely be untrue to say that it contains as large a portion of insalubrious territory as Italy itself, and produces fever and disease of as great severity and extent, not merely on its sea coasts, but over very extensive tracts in its interior. And this insalubrity may be conjectured, when there are entire districts in which the average of life does not exceed twenty, and in which the entire people are diseased from their births to their graves. Such tracts are found chiefly on the course of the Loire, and some other of the great rivers; and among them, Bresse in the Lyonnais, the plain of Forez, and Sologne in the Orleannais, are of the most notorious; while the coasts of Normandy, and the whole of low Britanny, are similarly subject to eternal intermittents, or to epidemic seasons of autumnal fevers, amounting to absolute pestilences. And how English families have suffered in this country from the incautious choice of residences in such places, will be easily ascertained by whoever shall be at the trouble of making the necessary inquiries.

But as I dare not pursue this extensive subject, I can only suggest to our countrymen the utility of making themselves acquainted with this matter, and with this dangerous geography, before encountering the hazards which await them; while to physicians I need still less name the necessity of that knowledge, since it is so often their duty to choose and recommend for their patients, and since no man can feel much at his ease who finds that he has sent into a land of malaria the patient who has already been suffering from its diseases, or that where he speculates on the cure of a consumption, that cure is attained through the death of the patient, at Avignon, or at Poitiers, or Nantes, or in some or other of the numerous places subject to this most fearful poison.

It remains only to give a brief enumeration of the diseases [p058] which are the produce of malaria, and of the general condition of the inhabitants in the countries subject to it. With respect to this latter, the most remarkable general fact is the contracted duration of life. In England, the average may, if not very accurately, and indeed considerably under the mark, be taken at 50; and when in Holland it is but 25, it follows that the half of human life is at once cut off by this destructive agent. In the parts of France to which I have alluded, it becomes as low as 22 and 20, and Condorcet, indeed, has calculated it as low as 18. With this, very few attain the age of 50; and in appearance and strength, this term is equivalent to 80 in ordinary climates; while 40 forms the general limit of extreme and rare old age. The period of age, indeed, commences after 20; and it is remarked, in particular, that the females become old in appearance immediately after 17, and have, even at 20, the aspect of old women. In many places, even the children are diseased from their birth; while the life which is dragged on by the whole population, is a life of perpetual disease, and most frequently of inveterate and incurable intermittents, or of a constant febrile state, with debility, affections of the stomach, dropsy, and far more than I need here enumerate.

While the countenances of the people in those countries are sallow or yellow, and often livid, they are frequently so emaciated as to appear like walking spectres, though the abdomen is generally enlarged, in consequence either of visceral affections or dropsy. With these, rickets, varices, hernia, and, in females, chlorosis, together with scorbutic diseases, ulcers, and so forth, are common; and it is even to be suspected that the cretinage may depend on this cause, since goitre is also one of the results of malaria, and since, in the Maremma of Tuscany, idiotism is a noted consequence of this pestilential influence.

The general mental condition is no less remarkable; since it consists in an universal apathy, recklessness, indolence, and melancholy, added to a fatalism which prevents them from even desiring to better their condition, or to avoid such portion of the evils around them as care and attention might diminish: and while it is asserted that even the moral character becomes [p059] similarly depraved, I prefer a reference to Montfalcon for a picture which it would not be very agreeable to transcribe.

As to the absolute or positive diseases, besides those which I have already named, I need scarcely say that remittent and intermittent fevers, under endless varieties and types, form the great mass; and next in order to them, may be placed dysentery and cholera, together with diarrhœa. To these I must also add, those painful diseases of the nerves, of which sciatica stands foremost, and the remainder of which may be ranked under the general term of neuralgia; and further, a considerable number of inflammatory diseases of a more or less remittent type, among which rheumatism under various forms is the most general, and the intermittent ophthalmia the most remarkable. Lastly, I must include the various paralytic affections; since apoplexy is one of the primary and direct consequences of malaria, as various paralytic affections are the produce of intermittent, or the consequences of the diseases of the nerves which are associated with it.

It is still a curious and interesting fact, that this poison affects, in an analogous manner, many different animals, and appears, in reality, to be the cause of all the noted endemics and remarkable epidemics which occur in the agricultural animals in particular. This has been noticed even by Livy: and in France and Italy it is equally familiar that the severe seasons of fever among the people are similarly seasons of epidemics to black-cattle and sheep, while the symptoms are as nearly the same as they could be in the circumstances, and the appearances on dissection also correspond. Thus also does it appear probable, that the rot in sheep is actually the produce of malaria, as is indeed the received opinion among French veterinarians; while Mr. Royston has observed that the animals of this class are subject to distinct intermittents.

And while it is not less familiar in the West Indies, and in Dominica particularly, that dogs suffer from a mortal fever in the same seasons and periods as the people, the epidemic always breaking out in them first, I have the most unexceptionable medical evidence of the occurrence of a regular and well-marked tertian in a dog; that evidence consisting in the concurring decision of many surgeons, by whom the case was [p060] frequently examined, during a very long period. But it is time to terminate a paper, which, if it is but a sketch of an important subject, will at least convey to those to whom malaria has not hitherto been an object of attention, a general notion of the leading particulars which appertain to its natural history.

J. M.

_Elements of Chemistry, including the recent Discoveries and Doctrines of the Science. By_ Edward Turner, M.D., F.R.S.E., &c., &c. _Edinburgh_, 1827.

This is a closely-printed octavo of 700 pages, and presents us with something more original, clear, and accurate than we have lately met with in modern chemistry. It comprehends a perspicuous view of the present state of chemical science; and, as far as its limits admit, the theoretical parts are, with some exceptions, well and distinctly worked out; nor are the practical details of manipulation neglected, though they evidently occupy a secondary place in our author’s estimation. To the arrangement we must at once decidedly object—it is indeed evident that Dr. Turner has pitched upon Dr. Thomas Thomson as his _magnus Apollo_, and here and elsewhere the book is tainted accordingly.

This work is divided into four principal parts;—the first relates to what Dr. Turner, following his prototype, Dr. Thomson, calls _imponderables_, and a definition of them follows, which leads us to suggest the term _inexpressibles_, as equally appropriate. But, waiving this objection, the details relating to them are well and clearly given. Thus, after some prefatory remarks upon the subject of caloric or heat, (we prefer the latter term, and cannot allow its ambiguity,) its modes of communication are considered, first, as being _conducted_ through bodies, and then as _radiating_ through free space. In regard to the theories affecting the latter, our author wisely, as we think, prefers that of Prevost to that of Pictet. The _effects_ of heat are next discussed, such as _expansion_, including an account of the thermometer, and of the relative capacities of bodies for heat; _liquefaction_, _vaporisation_, _ebullition_, _evaporation_, and the _constitution of gases_ and lastly, the sources of heat are mentioned, but the details are referred to other parts of the work. [p061]

_Light_ is next treated of, but we think too hastily, and too much in the abstract.

Now the subjects of heat and light are obviously of the utmost importance to the chemical philosopher, and they are very extensive, and intricate and difficult to treat of, inasmuch as the writer is necessarily upon the confines of chemical and mechanical philosophy, and should be expert in both. When, therefore, elementary works on chemistry are so written and arranged as to serve as text-books for lectures, and indexes of reference to more accurate information, we can make due allowance for brevity; but when the subject is intended to be formally and completely developed to the student, independent of other ocular and oral aids, much more extensive description and detailed explanation is required, than is to be found either in our author’s “Elements,” or in any other analogous condensation of chemistry. Dr. Henry understands the requisite mode of conveying information in these cases better than most writers; and when he takes pains, and speaks for himself, has the talent of being brief, and at the same time minute, deep, and clear. Dr. Ure, as his dictionary shows, is an eminent example of such a writer—_he_ of course is neglected, where, as with our author, Dr. Thomson is in the ascendant; but the article caloric, in his dictionary, will at once explain and illustrate our meaning, and would furnish an admirable foundation for a detailed essay or treatise upon the subject. So extensive, indeed, are the precincts of chemistry now becoming, that either our _systems_ must become very voluminous, or we must adopt the plan, which to us appears preferable, of distinct treatises upon different branches of the science. Thus, a separate work on heat and light; another on electricity and magnetism; another on attraction and the theory of combination; a fourth on the constitution and properties of the unmetallic elementary bodies; a fifth on the metals and their compounds; a sixth on vegetable, and a seventh on animal chemistry and physiology; an eighth on the chemistry of the arts; and lastly, a treatise on chemical manipulation in general, would include all that appears essentially requisite; and as no one is supposed to be equally well versed in all branches of the science, or in all details of the art, an opportunity of selection would thus be afforded, so that each writer might choose that particular department which he is most accurately acquainted with, or which has formed his favourite study. Mr. Faraday has already, as may be said, led the way in such a plan, by the publication of his _Chemical [p062] Manipulation_, a work hitherto exceedingly wanted in the laboratory, equally useful to the proficient and to the student, and eminently creditable to the industry and skill of the author, and to the school whence it emanates. We shall of course take an early opportunity of introducing this book in a more formal way to the attention of our chemical readers.

In looking over Dr. Turner’s first and second sections on caloric and light, in the _Elements_ now before us, we find little but brevity to complain of;—there are, however, one or two trifling historical inaccuracies: thus, at page 14, the discovery of _invisible_ heating rays is ascribed to Saussure and Pictet; but it is, in fact, of much more remote origin—it was well known to the Florentine academicians, and we may even trace the idea in Lucretius, (_De Rerum Naturâ_, lib, v. 1, 609.)

Forsitan et rosea Sol alte lampade lucens Possideat multum _cæcis fervoribus ignem_ Circum se, _nullo qui sit fulgore notatus, &c._

At page 31 we have an account of Wedgwood’s pyrometer, which is said to be “little employed at present, because its indications cannot be relied on;”—the fact is, that it is never used, and that we owe to Sir James Hall ample reasons for placing no confidence in it.

The subject of _specific heat_ is clearly explained, and so are the phenomena of liquefaction and evaporation. In regard to the constitution of gases, the author remarks, that the experiments of Sir H. Davy and Mr. Faraday on the liquefaction of gaseous substances, appear to justify the opinion that gases are merely the vapours of extremely volatile liquids. Mr. Faraday has proved this in regard to several of the gases, and analogy leads us to apply it to the rest;—but what share Sir H. Davy had in the discovery, we know not; for Mr. Faraday actually condensed chlorine into a liquid before Sir H. had heard or thought about the matter. _Light_, and its phenomena as connected with chemistry, is superficially passed over in the second section, and the third brings us to the important article “Electricity.”

We are willing to admit that the subject of electricity is a very difficult one for the chemist to deal with—he must necessarily say much upon it, and is equally obliged to omit abstract details which are often necessary to its explanation, and yet too prolix and bulky for an elementary chemical work. So that it requires considerable acquaintance with the subject to give a perspicuous and yet concise abstract, [p063] such as may be useful to the student. Dr. Turner has not been very successful in effecting this _desideratum_, and has unnecessarily introduced two sections, the one on electricity, the other on galvanism. He also talks of the “science of galvanism,” which is in bad taste, and erroneously asserts that the energy of the pile is proportional to the degree of chemical action which takes place; a statement by no means correct, inasmuch as the energy of De Luc’s column is directly proportional to the number of alternations, and appears entirely independent of chemical action; and again, a series of 2000 plates, arranged in the usual Voltaic apparatus, when perfectly bright and clean, and the cells filled with distilled water only, give a much more powerful shock, and cause a greater divergence of the leaves of the electrometer than when the apparatus is charged with diluted acids. Here, those very singular phenomena, which electricians distinguish by the terms _quantity_ and _intensity_, appear perfectly distinct; and between these our author does not sufficiently discriminate, but jumbles the whole under the term _activity_. In describing the chemical energies, too, of the pile, or its decomposing powers, the Doctor entirely overlooks the important and curious influence of water. He says that acids and salts are all decomposed, without exception, one of their elements appearing at one side of the battery, and the other at its opposite extremity; (_i. e._ we presume, at its positive and negative poles.) But the fact is, that, excepting where it merely acts as a source of heat, nothing is decomposable by electricity without the intervention of water; the hydrogen and oxygen of which respectively accompany the elements of the other compounds. Not an atom of potassium can be obtained unless the potassa be moistened; nor can any salt be decomposed except water be present. Sir Humphry says, it is required, to render the substance a conductor; but its operation is more recondite, and there is something mysterious and still unexplained in the uniform appearance of hydrogen and oxygen at the opposite poles, when far apart in water, and in all other cases of true polar electro-chemical decomposition. At page 86, the unfortunate protectors of ships’ bottoms are introduced—a subject about which the less is said the better;—and, as to electro-magnetism, it is merely mentioned as to its leading phenomena, in the space of three or four pages; nor is anything new suggested upon the “Theory of the Pile,” as it is called, which concludes the subject, and which is dismissed in the brief limit of a page and a half. [p064]

The second part of Dr. Turner’s work is said to comprise “Inorganic Chemistry,” and therefore embraces a very extensive field of inquiry. To the _arrangement_ we have already objected; and many of the typographical and verbal errors that occur, have been noticed in a contemporary Journal, so that we shall chiefly attend to the details of the sections.

Under the head, “Affinity,” some of the leading facts and doctrines of chemical attraction are perspicuously set forth; but we could have wished that a variety of exploded opinions and erroneous notions had been altogether passed over, as they occupy space which might have been better employed, and can never prove of any other use to the student than to show him the errors and fallacies to which acute philosophers are sometimes liable. Of this kind, especially, are Berthollet’s notions upon the subject of affinity. The doctrine of definite proportion is, on the whole, well and clearly explained; but it would have been much better and clearer, had Dr. Turner confined himself to facts, and meddled less with opinions concerning their cause; he is moreover, in many respects, historically inaccurate. He ascribes much to Dalton that honestly belongs to Higgins;—is much too merciful to Berzelius and his CANONS; and lenient beyond all endurance to the plagiarisms of “Dr. Thomson’s admirable Treatise on the first Principles of Chemistry.”

In the third and following sections, the simple non-metallic substances are described in an order of arrangement which must be very perplexing to the student; otherwise the details are well given, except that here and there the line between theory and fact is not sufficiently marked. Thus we are told that “hydrogen is exactly 16 times lighter than oxygen, and _therefore_ that 100 cubic inches _must_ weigh 33.888/16, or 2.118. Its specific gravity is consequently 0.0694, as stated some years ago by Dr. Prout.” Now this is a theoretical deduction, founded upon the specific gravity and constitution of ammonia, (and not upon the composition of water,) and probably correct as applied to _pure_ hydrogen;—but if we weigh the gas, as usually obtained, even with the utmost caution, and of the utmost purity, we shall never procure it so light as here stated, notwithstanding all the learning and argument that our worthy friend, Dr. Thomas Thomson, has issued upon the subject in his various essays in the Annals, and in his _magnum opus_. We also object to the stress which is often laid upon the whims of individuals, and upon [p065] exploded opinions; instances of which will occur to the reader under the subject of the composition of nitrogen, and the constitution of the atmosphere. We further caution our author against admitting hints, allusions, and inuendos as to the possibility of future inventions and discoveries, as claims upon the merits of such discoveries, when they are actually made. Berzelius has talked a vast deal of nonsense about the composition of nitrogen; and should that discovery ever be made, he will doubtlessly assume the credit of having suggested the steps which led to it. Some foolish persons are apt to think that the Marquis of Worcester was the inventor of Watt’s steam-engine, because he said he had means of raising water by steam, in his _Century of Inventions_; and we have heard that an eminent chemist of the present day considers himself entitled to all the merit that may belong to Mr. Brunel’s carbonic acid engine, because he had previously stated the possibility of such an application of Mr. Faraday’s important discoveries. The fact is, that these are woeful days for science; all the good feeling and free communication that used to exist among its active cultivators in this country, has given way to petty jealousies and quibbling scandal; one person is exalted for the purpose of depreciating another; and those causes of disgust, which some years ago induced one of our most amiable and able men of science to quit the field, and even leave the country, are becoming daily more prevalent. Were it not an invidious task, we could easily explain and unfold the sources of all this mischief, and shall indeed feel it our duty so to do, should not matters in due time take a more favourable turn; but the task is at once serious and disagreeable, and we therefore postpone it, in the hope of more favourable events. We really believe that, had it not been for the scientific conversationes held during the last season at the houses of a few private gentlemen connected with the learned societies, and more especially the weekly meetings at the Royal Institution, which kept up a friendly intercourse among those who were willing to profit by it, that the whole scientific world would have been at loggerheads, and in that state of anarchy of which the evils may be learned by a short residence at a “northern seat of learning.”

The main object of this digression is to deprecate _party_ in science; and we were led to it by observing, or thinking that we observe, something of such a tendency in the writer whose book is before us—we hope we are mistaken.