however, be faithful, even though his re- EXERCISE. By exercise, the stomach is strengthened, the digestion rendered better, the blood ameliorated, and every animal function improved. The mind also becomes more courageous, corporeal sufferings are borne with patience, a command of temper, and a presence of mind, are acquired and preserved undisturbed amidst pain and danger; the understanding is clear, the imagination untroubled, and the spirits in a fit state for the proper and the most vigorous exertion of our intellectual powers. By this means, also, disease may often be prevented, and not unfrequently cured, even when it has taken a very strong hold of the constitution. can well understand the smile that expanas the parent's brow, at the display of precocious knowledge which his embryo representative is thus made to exhibit; but did he know the anxious days, the sleepless nights, the pains and lassitudes, he lays the foundation for, by thus straining the tender springs of life, and thwarting nature in her efforts to mature the man, his smile would give place to feelings of a different kind. In this respect, parents would do well to take a lesson from the lower animals, which act by the unerring instincts which the Almighty has implanted in their nature, and whose actions must be therefore right. Witness the gambols, the constant activity, and the light-hearted cheerfulness of the unrestrained young of all animals, and the encouragement to this sportiveness which they receive from their parents: and after having done so, attentively compare the proportion of cases of bodily deformity amongst them, and amongst men who act by the guidance of reason; and see the immense superiority which their practice has over ours in that respect, and whether it might not be worth our while to profit by the lesson thus afforded us.-. -Henderson. We consider, from the observations we have made upon the subject, that no hinderance is thrown in the way of physical growth, or a happy developement of the vital energies, by sowing the infant mind with the seeds of wholesome knowledge, in a way suited to their age and capacity. CHEMISTRY.-No. III. HEAT AND COMBUSTION. BEFORE we proceed to notice, in succession, the properties of the various substances that fall within the province of Chemistry, it is necessary briefly to direct the attention of the reader to certain remarkable phenomena, developed by the action of heat, on the bodies to which it is applied, as well as to a brief consideration of the phenomena of combustion. Thus, curvature of the spine and deformity of the chest, complaints which are to be met with so very frequently of late years, particularly among girls and young women in the respectable and higher classes of society, but seldomer among boys, or the children of the poor, originate in debility of the constitution, by which the bones become soft, and consequently yield to the force of the strongest muscles, or to the weight of the superincumbent pressure. The chief, if not the only cause of this debility, may be traced to the unnatural and Heat pervades all bodies; existing, either absurd systems of infantile education, so in an insensible, or latent form, not being commonly practised at the present time, perceptible to the touch; or, in a sensible whereby children are mewed up in nur- form, in which state its presence is made series, and other close and heated apart-known by the thermometer. A variety of ments, during the greater part of the day. By thus being deprived of exercise in the open air, their powers of life are directly debilitated, and this debility is further increased by attempts to strain their undeveloped minds to the comprehension of things altogether above their understandings. We experiments will illustrate this remark. By hammering a piece of wrought iron, by friction, and other means mentioned in page 213 of Weekly Visitor, for 1833, latent heat may be extracted from bodies in a sensible form. If a portion of sulphuric acid and nitric acid be mixed together in a cup, and the mixture poured into another cup, containing a small quantity of oil of turpentine, so violent an action is produced, that the whole will burst forth into a brilliant flame. This arises from the circumstance, that the compound has less capacity for heat, than the component substances before they were united. By the application of heat, the bulk of all bodies, whether solid, liquid, or aeriform, is extended; and by extracting it from them, their bulk is proportionably diminished. This might be illustrated by many simple experiments. A knowledge of the theory of the thermometer is sufficient to furnish a satisfactory illustration of this fact. Heat is, in fact, the antagonist of cohesion; and it is this property that renders it the most important agent to the chemist, in his examination of different substances. There exists a larger quantity of latent heat in fluids than in solids, and a still greater quantity is possessed by the gases. The heat requisite to preserve a body in a liquid state, is called the caloric of fluidity; the quantity required to preserve a gaseous body in its particular form, the caloric of vaporization. Whenever, therefore, a fluid is converted into a solid, or a gas into a fluid, the additional heat it possesses escapes in a perceptible form. In the slaking of lime, the water that is used loses its fluidity, and forms a powder with the lime, and during this process, the hot steam that arises from the mixture, is the result of its passing from fluidity to solidity. On the contrary, when a fluid is converted into a gas, heat is withdrawn, and cold is produced. If a thin tube be wrapped round with muslin, and the muslin be repeatedly moistened with the substance called ether, in process of time, the water in the tube will be frozen. The cold is produced by a part of the ether, passing (by evaporation) from the state of a fluid to that of a gas. Another important property of heat is, to accelerate the solution of salts. Two ounces of Glauber's salts (sulphate of soda) put into a tea-cup of cold water, will not entirely unite with the water; but by applying a sufficient degree of heat, the whole will be dissolved. It is not necessary that these remarks should be further extended on the subject of heat, as its properties have already been more fully stated in the Weekly Visitor for 1833, (pages 213, 258.) It may, however, be interesting to the reader to know, that we are enabled to excite a much greater degree of heat, than o cold. The greatest cold produced, is 122o below the freezing point. But a furnace has been constructed, by which an intensity of heat, equal to 25127° of Fahrenheit has been exhibited. But even this heat is far below what may be produced, by means of a Galvanic apparatus. The phenomena of combustion, or the process commonly called burning, is but imperfectly understood. Many ingenious theories have been offered by different philosophers, who have closely investigated the subject, but even now, there is some diversity of opinion respecting it. The theory of Lavoisier, an eminent French chemist, has, of late years, attracted most attention, and appears most accordant with facts. In his theory, combustion is described as the combination of any body with oxygen. There may be, however, so many instances adduced, wherein combustion evidently takes place without the presence of oxygen, that serious objections are urged against this theory. It appears an unwarrantable practice adopted by some chemists, to apply the term combustion only to those processes of burning in which oxygen is presented; but in all other cases, (and there are as many instances on one side as the other,) to apply the term deflagration. Professor Donovan, in his treatise on Chemistry in Lardner's Cyclopædia, observes, "that it is perhaps the safest, because the most comprehensive idea for the student to entertain of combustion, that it is the emission of light and heat from bodies in the act, generally, of combining, but sometimes of separating; that the heat is part of the combined, or latent caloric of the combining bodies; that the light may also proceed from them, although it seems chiefly dependent on one of them,-the combustible." In the phenomena of combustion, we have an illustration of the foregoing remarks, respecting the heat that is evolved from a gas when in the act of combining with another substance, and losing its gaseous form. When the oxygen, or other gas, is absorbed by the combustible body, the heat that escapes is thus explained. "Combustion, therefore, like all other chemical processes, may be explained by the laws of chemical affinity. The combustible having a greater affinity to oxygen, than oxygen has to heat, the oxygen gas is disengaged, and combines with the ignited body, while its caloric, becoming free, produces the heat which is diffused among the surrounding bodies. As the oxygen unites with the combustible, it becomes more dense than when in the state of gas; consequently, it has less capacity for caloric than it had; a portion of it, therefore, must be given out before the oxygen can combine with the new substance that attracts it from its former combination."* When a body has combined with the greatest portion of oxygen, or other supporter of combustion that it will absorb, it is termed an incombustible body. It is by combustion that substances are converted into acids and oxides, two classes of bodies to which we shall afterwards devote more particular attention. A close examination of all that takes place in substances during the process of burning, will prove the fallacy of a common opinion, with those who are unaccustomed to philosophical pursuits, that in this way bodies are destroyed. It is a remarkable fact, asserting, in an eminent degree, the consummate wisdom of the Creator, in establishing such a provision, that no particle of matter is in this way destroyed; but that the several component parts of any substance are merely separated, and thus prepared to unite with other bodies, and form new compounds. We have abundant reason to believe, that it is beyond the power of man to annihilate one particle of matter, and that all the varieties of form in which matter may be presented, arise from the successive changes through which those indestructible atoms pass, of which the earth was originally constituted; directed by the simple and comprehensive laws our all-wise Creator has established. MEDICAL PROPERTIES OF UMBELLIFEROUS PLANTS. IF plants engage our attention by curiosity of structure, and the beauty of their form, they become doubly interesting, when we regard them as yielding either food for our sustenance, or medicaments for the restoration of our health. All can easily comprehend why we should occupy ourselves in the search after plants or simples, when experience shows, that they may be made to minister to our comfort or our necessity. When the writer was travelling in South America, he was often asked by the uninstructed natives, why we devoted so much time and attention to gathering wild flowers; but, when he introduced the explanation of our views by saying, “para los remedios," that they were for pharmaceutical or medical purposes, we found them pre * Parkes. | pared to listen to us, while we proceeded to state, that their texture, and genera. history, as well as their useful properties, were matters of anxious curiosity with us. In the same way, we are going to call the mind of the reader to the study of the umbelliferous plants, by showing what reference many members of this order have to the well-being of man; that those who are not affected by the native grace and propriety of knowledge, when unaccompanied by profit, may be induced to think well of the science, for the sake of its utility. Angelica Archangelica, garden angelica. This plant is a native of Lapland, diffused over all the hilly parts, near streams of water. The Laplanders, as Linnæus informs us, entertain a high opinion of the utility of angelica, and employ it both as a food and medicine. As aromatic plants are rarely found near the polar regions, it is easy to account for the high character which it has obtained among them; for its root has a fragrant, agreeable smell, and a warm, aromatic taste. Lewis says, that " on wounding the fresh root early in the spring, it yields from the inner part of the bark an unctuous, yellowish, odorous juice, which, gently insiccated or dried, retains its fragrance, and proves an elegant aromatic gummy resin. On cutting the dry root longitudinally, the resinous matter, in which the virtue and flavour reside, appears concreted in little veins." tified spirit will extract the whole of the virtues of the root; while water, which happens in many other instances of the like nature, will take up but a very small part of its peculiar qualities. If the root be distilled with water, a small portion of an essential oil, with a very pungent taste, may be obtained. Rec Angelica sylvestris, wild angelica.Found in marshy woods and hedges. It possesses the properties of the archangelica, but not in so high a degree; and it is not so easily met with, since the other is commonly cultivated in our gardens. Phellandrium aquaticum, fine-leaved water hemlock.-This plant may be distinguished by the unusual size of the stem, the fineness of its leaves, and the position of its branches, which are nearly at right angles to the stem from which they proceed. The seeds, according to Dulange, when taken in large doses, produce a remarkable sensation of weight in the head, from Turkey or the East Indies, is not the production of the plant before the reader, but of some other species of the same genus. This drug comes to us in large softish, pliant, and pale-coloured masses, which, by keeping, acquire a brownish yellow appearance. These masses are intermixed with distinct clots or tears, which are accounted the best part of them. We find, the colour of the galbanum was a favourite among the Romans, so that galbana rasa, or the hue of galbanum, when scraped, is reckoned by the Roman satirist among the marks of an excessive fondness for dress and fashionable display. accompanied with giddiness, intoxication, and an acrid biting taste. Competent &c., and therefore may be deemed ca-judges are of opinion, that the galbanum of pable of proving an active medicine. the shops, which is generally imported Pliny, who is followed by Doronæus, states, that the seeds are efficacious in the case of calculus, and other disorders of a similar origin. But, in looking over the catalogue of maladies in which this plant is said to be useful, we find that incoherence which makes us suspect the authority of our forefathers; for diseases of an entirely opposite character, and, of consequence, requiring treatment as different, are to be cured, according to them, by administering one and the same remedy. Enanthe crocata, hemlock water dropwort.-Dr. Poulteney has borne his testimony to the efficacy of the juice of this plant in disorders of the skin, but its application was attended with the most alarming symptoms, as it is allowed to be the most fatal of vegetable poisons that are found in this country. Various melancholy instances attest the virulence of this poison; and it is mentioned here, chiefly to caution persons gathering wild salads, against its use. If we cannot teach our country readers to distinguish this weed from the rest of its related plants, we can deliver a very safe and unerring rule, which is-Never to meddle, but for purposes of inspection, with any plant growing in the water, that resembles parsley or celery, for they generally possess active, and very often poisonous qualities. The Cicuta virosa, or water hemlock, which may be distinguished by having its clusters of flowers opposite to the leaves, and the wide foot-stalk of the latter, is poisonous, and is supposed by Haller to have been the hemlock of the Greeks; of which the fickle Athenians administered a fatal dose to Socrates, their greater master of morals. It grows in pools and ditches, and flowers in July and August. Bubon Galbanum, lovage-leaved bubon.-From this plant the galbanum, used in medicine as an anti-spasmodic, is supposed to be derived. The bubon galbanum is a native of the Cape of Good Hope, and was first introduced into Britain by Mr. John Gerard, in 1596, and is now cultivated in the King's Garden, at Kew. The stalk is shrubby, several feet high, slender, purplish, and covered with an ash-coloured exudation. It is round, bending, and knotted, towards the bottom woody and naked. The whole plant presents a smooth appearance, and has an aromatic smell, Carum Carui, common caraway.This plant is a native of Britain, growing in low meadows, where it flowers in May and June. The properties of the seeds, which are so familiarly used for economical purposes, are too well known to make it necessary for us to enlarge upon them. It is, however, remarkable, that in distillation with water, that is, if the seeds be put into water, and that water be made to evaporate, the steam carries away all its aromatic part, without leaving any bitterish or ungrateful matter in the water; proving that nothing unwholesome is mixed up with the agreeable and useful qualities of this condiment. Ferrula Assafoetida, assafoetida gigantic fennel. This plant is a native of Persia, and was first cultivated in England by Dr. Hope, in the botanical garden at Edinburgh, in 1814. Kompfer was the first who obliged the world with an accurate description. The stalk, which is two or three yards high and upwards, and six or seven inches in circumference, together with the rest of the herbage, sends forth a strong smell of garlick, but it is from the root the juice is obtained, which, after becoming concrete, is known in our shops by the name of assafœtida. Kompfer thus describes the manner in which it is procured on the mountains in the provinces of Chorasan and Zaar in Persia. At that season of the year when the leaves begin to decay, the oldest plants are selected. First, the earth which surrounds the root is rendered light, by digging, and part removed, so as to leave a portion of the root bare; the leaves and stalk are then twisted off, and employed, with other herbs, in constructing a screen to defend it from the sun. In this state, juices of plants, and to approach in obvious properties to animal milk, from which it differs widely in chemical composition. There is no cream or caseous (cheesey) matter; I kept a little of the milk until our arrival at Trinidad, eight weeks after my procuring it, when it was sent to the admiralty. Some, which I had myself, had then separated into a sourish milky water and a white solid mass, which, when taken out and dried in the air, was a white inflammable substance, not softening at the tem the root is left for forty days; after which, the covering is removed, and the top of the root cut off; it is then screened again for forty-eight hours, when the juice that has exuded upon the wounded surface is collected by means of a proper instrument. This operation is repeated three times at the end of successive periods of forty-eight hours. After the third time, the root is suffered to remain unmolested for eight or ten days, when a similar process for collecting the juice is again repeated. Its qualities are highly stimulat-perature of the body, melting at 143°, ing, and it is of great service, especially in cases of torpid digestion. tasteless, insoluble in water or spirits, and resembling white wax more than any other Imperatoria Ostruthium, the common substance to which I could compare it. It master-wort, is a native of Scotland; as burned with a bright agreeable flame, withit was found several times by Mr. Light-out smelling, and was neither greasy nor foot, growing wild upon the banks of the resinous; I am, therefore, inclined to conClyde. It is cultivated in our gardens; sider it a species of wax." but the shops are generally supplied from the Alps and the Pyrenees; as that which grows in the southern countries is much superior to what is produced among us. The bare denomination of this plant, master-wort, the master herb, intimates to us the high character, for healing qualities, it was once supposed to possess. But the estimation for almost supernatural, "divinum," qualities, has dwindled by time and discovery into that of simply aromatic. THE PALO DE VACA. THE Palo de Vaca, which flourishes in Para,in South America, is among the loftiest trees of the forest, growing to the height of a hundred feet and upwards. It bears a delicious edible fruit, which has the united flavour of strawberries mixed with cream, and its trunk yields as fine bowls of milk as those from a cow! "It seems rather startling," says our author, "to talk of a tree yielding milk, but such is the fact; and it is drunk by the people in large quantities, and was used by us, at the gun-room table, for mixing with tea, in lieu of cow's milk, from which it is no ways distinguishable in general use. The milk is a rich, white, bland fluid, without odour, and of the taste and flavour of common milk. It mixes readily with tea or coffee, without curdling or undergoing any change, and in every respect seems like cow's milk. Boiling water does not alter it. It keeps unaltered six or seven days in the temperature of 85°****. It appears to differ from all the known milky To complete the marvels of this tree, we must mention, that it affords the most valuable timber for ship-building, and that it is so used in the dock-yards at Para.—From Webster's Narrative of Foster's Voyage in the Chanticleer. CONTRADICTIONS. IN unclear and doubtful things, be not pertinacious, as the weakest minds are readiest to be upon seeming reason, which, when tried, will possibly fall to nothing; yet they are most assured, and cannot suffer a different thought in any from their own. There is naturally this popeness in every man's mind, and most, I say, in the shallowest; a kind of fancied infallibility in themselves, which makes them contentious, contrary to the apostle's rule, "Let nothing be done through strife or vainglory," Phil. ii. 3, and as earnest upon differing in the smallest punctilio, as in a high article of faith. Stronger spirits are usually more patient of contradiction, and less violent, especially in doubtful things; and they who see furthest, are least peremptory in their determinations. The apostle, in his second epistle to Timothy, hath a phrase, "the spirit of a sound mind:" it is a good, sound constitution of mind, not to feel every blast; either of seeming reason, to be taken with it; or of cross opinion, to be offended at it.-Leighton. JOHN DAVIS, 56, Paternoster Row, London. W. TYLER, Printer, 4, Ivy Lane, St. Paul's. |