Popular Science Monthly/Volume 7/August 1875/Miscellany
Fish-Culture.—The results so far attained in this country in the artificial culture of fish are eminently satisfactory, and the efforts made by the various fisheries commissions to increase the supply of food for the people are worthy of all commendation. Naturally, there exists a lively public curiosity to know the processes of fish-culture, and information with regard to its history, its principles, and its methods, is heartily welcomed. In response to this general demand, Mr. Robert B. Roosevelt, Fish Commissioner of the State of New York, has given a public lecture on pisciculture, in which he very fully considers the subject in all its aspects. The lecture is very long, and we must be content with indicating only a few of its points. There are, he said, two divisions of fish in our country which are subjects of fish-culture, viz., the Salmonidæ, or salmon-tribe, and the Alosidæ, or shad-tribe. Under the former head are included the salmon, the trout, the salmon-trout (or lake-trout), the whitefish, and the California salmon. The Alosidæ are represented in pisciculture only by the shad, as yet.
The first point in fish-culture is to obtain the spawning-fish in proper condition. In the Salmonidæ, the eggs, when in a perfectly ripe condition, lie free in the abdomen, and may be extruded by gentle pressure. They are caught as they fall in a basin, and are vitalized by coming in contact with the milt from the males. Formerly, the practice obtained of having this basin full of water, it being supposed that this arrangement more nearly reproduced the natural conditions; but subsequent discoveries led to a change of this method. The eggs are fertilized by the spermatozoa of the milt entering through the micropyle, and taking up board and lodging within. It was ascertained, however, in practice, that these spermatozoa are not fond of water, and, although very active when first emitted, soon drowned. They retain their vitality much longer when dropped among the eggs in a comparatively dry state, and this is the method universally pursued at present.
As soon as the operation is completed, the eggs are placed in hatching-troughs. These are made of various materials, but are simply long, narrow boxes, say twelve feet long by eighteen inches wide, and subdivided into compartments, to keep the eggs from crowding on one another. Cold spring-water, which has been carefully filtered by passing through several flannel screens, comes in at the head of these troughs, passes over the eggs, in one compartment after another, and escapes at the lower end. By this means the greatest dangers to the life of the embryo are avoided. Sediment and confervæ cannot pass the screens, insects are kept out altogether, and ducks and eels are disappointed of their prey. The eggs require about two months to hatch, with the water at the temperature of 45°. They demand constant care and attention, for, if one egg dies or becomes diseased, it contaminates its neighbors. The advance of the process is, however, soon visible in the egg, either to the human eye or under the microscope. At last the pisciculturist will have evidence of his labors being successful. Some morning, on going to his troughs, he will notice broken egg-shells in the water, and, on closer inspection, will observe wriggling nondescripts on the bottom, neither like fish nor eggs, but compounded of both. When they once begin to appear, they come in thousands, in millions, in myriads. The young need more water, at this time, but require less care; yet still they must be watched. The young fish may soon be turned loose into the stream.
If he is a salmon, after a few months' preparation to strengthen his sinews and test his power, he goes down to the sea, there to dwell, and feed, and grow, gaining wonderfully in size, drawing his sustenance from the exhaustless storehouse of the world, and coaling back to man, in a few months, a magnificent embodiment of strength and beauty, bringing to the lord of the universe five or ten pounds of as delicious food as ever delighted a gourmand's palate, or satisfied a hungry man's stomach. If he is only a trout, a younger brother of the glorious family of the Salmonidæ, he will lurk about the bottom of some pond, or graze some pebbly mountain-brook, and struggle up to a half-pound or more before twelve months shall have rolled over bis head.
Heat evolved by Friction of Ice.—Mr. A. Tylor, in a paper recently read before the Geographical Society of London—a synopsis of which was published in Nature—shows that heat evolved by friction of ice upon ice is an important element in glacial movement. By a simple apparatus he reduced ice to water in a temperature of 32°, at the rate of one and a quarter pound an hour, by friction only of ice upon ice, the pressure applied being but two pound to the square inch. By simple evaporation, the ice in the same temperature lost one-quarter of a pound in the same time.
In a temperature of 54° the production of water under friction was three and a quarter times greater than by simple melting when there was no friction.
The actual heat evolved by friction of ice upon ice is nearly the same as from oak upon oak, when well lubricated.
In the motion of glaciers great quantities of water are continually discharged, lubricating the bottom. Surface-melting of the ice Mr. Tylor considers insufficient to produce it. The bottom of a glacier, with its rasping under-surface of rock and sand, slides, to some extent, upon the bottom, and much heat is evolved in this way, but in innumerable fractures of the sides of the glaciers, of the surface-ice flowing on and over bottom-ice, there are friction and attrition, ice moving against ice, which melts it, and the water percolates through the fractures to the bottom.
In great glaciers. the pressure is enormous. With ice a mile thick it is half a ton to the square inch, and the quantity of water produced increased accordingly.
Economic Value of the Sunflower.—The common sunflower is a native of tropical America, and there it sometimes attains the extraordinary height, for an annual plant, of twenty feet. It thrives in nearly every region of the inhabitable globe. In the south of Europe and in the northwest provinces of India it is cultivated to a considerable extent. In the latter country, sunflower-plantations are said to have a very beneficial effect in promoting the healthfulness of regions infested by malarious fevers. The seeds are valued as food for cattle and poultry, and an oil may be expressed from them which is scarcely inferior to olive-oil. One acre of good land will produce about fifty bushels of seed, each bushel yielding a gallon of oil. The seeds are also used like almonds for making soothing emulsions, and, in some parts of Europe, a food for infants is prepared from them. In tropical America the Indians make bread of them. The leaves are used as fodder for cattle, and the stalks, when burned, yield large quantities of potash.
The plant called Jerusalem artichoke is doubly misnamed; it has as little to do with the Holy City as the soup made from its tuberous roots has to do with the Promised Land, and yet the former is called Jerusalem (from the Italian girasole—sunflower), and the soup is called "Palestine," because it contains "Jerusalem." It got the name of "artichoke" from a resemblance in taste between its tuber and the flower-receptacles of the true artichoke, but it differs totally from that plant in botanical characters. The Jerusalem artichoke is a species of the sunflower, and, like all sunflowers, a native of tropical America. It has a straight stem, eight or ten feet in height, and produces yellow flowers like those of the sunflower, but smaller. The thick, fleshy, perennial root produces a large number of tubers, in appearance not unlike potatoes. These are not as nourishing as potatoes, but, when properly prepared, are very palatable food, and make a very good soup. It is usually propagated by small tubers or by cuttings, like the potato.
Toughened Glass.—A process for increasing the cohesive power of glass has been invented by a French engineer, François de la Bastie. This process consists in heating the glass to a certain temperature and plunging it while hot into a heated oleaginous compound. The time occupied in the actual process of tempering is merely nominal, for directly on being heated to the requisite degree, the articles are plunged into the bath and instantly withdrawn. The toughened glass cannot be cut by the diamond, and hence when it is used for windows it must be cut to the proper size before it is tempered. Articles of this toughened glass, such as watch-crystals, plates, dishes, and sheet-glass, were recently exhibited in London, and experiments made to show wherein this material differs from common glass. Water was boiled in a saucer over a fire, and the saucer quickly removed to a comparatively cold place; it was unaffected by the sudden change of temperature. One corner of a piece of glass was held by the hand in a gas-flame until the corner became exceedingly hot, but the heat was not communicated to the other portion of the glass, nor was it cracked from unequal expansion.
The following experiment was then made to show how this toughened glass compared with common glass in power of resistance to fracture by the impact of a falling weight. The two pieces of glass to be tested were each about six inches square, and placed in frames, the weight being dropped upon the centre. With the ordinary glass, a two-ounce brass weight, falling on it from a height of twelve and eighteen inches respectively, did no damage, but at twenty-four inches the glass was broken into fragments. With a thinner piece of the toughened glass no impression was made by the same weight falling from heights ranging from two to ten feet, the weight simply rebounding from the glass. An eight-ounce iron weight, tried at two to four feet respectively, gave similar results. The height being increased to six feet, the glass broke.
Some of the public prints have ascribed to Bastie's tempered glass properties which the inventor himself has never claimed for it. Thus it has been qualified as malleaable and "unbreakable." But Mr. Thomas Gaffield, of Boston, a perfectly competent judge, who has examined specimens of this tempered glass, thinks that the true value of this invention is by no means determined as yet. He perceives in it sundry qualities which detract from its usefulness. First, as we have stated, it cannot be cut by the diamond. Then, on being subjected to the sand-blast, it flies into small fragments. Many of the specimens seen by Mr. Gaffield were not transparent, but only translucent. In ordinary window-glass, if a large pane be broken, the fragments may be cut into smaller panes, but with the De la Bastie glass such economy is out of the question. From the fact that this improved glass, though before the public for a whole year, has not yet found a place in commerce, Mr. Gaffield is inclined to suspect that the invention is for some reason impracticable.
Can Birds converse?—Dr. Charles C. Abbott cites the following occurrence to show that birds possess some mode of conveying ideas to one another. In the spring of 1872 a pair of cat-birds were noticed carrying materials for a nest to a patch of blackberry-briers hard by. To test their ingenuity, Dr. Abbott took a long, narrow strip of muslin, too long for one bird conveniently to carry, and placed it on the ground in such a position as to be seen by the birds when searching for material. In a few moments, one of the cat-birds spied the strip and endeavored to carry it off; but its length and weight, however he took hold of it—and he tried many times—impeded his flight, and, after long worrying over it, the bird flew off for assistance. In a few moments he returned with his mate, and then, standing rear the strip, they appeared to hold a consultation. The chirping, twittering, murmuring, and occasional ejaculations, were all unmistakable. In a few moments these all ceased, and the work commenced. Each took hold of the muslin strip, at about the same distance in each case from the ends, and, taking flight simultaneously, bore it away. Soon there was much jabbering at the nest: the birds could not agree how to use the strip, and it was finally abandoned; but so, too, was the nest, and the birds left the neighborhood.
Parasite in a Child's Mouth.—At a meeting of scientific men lately held in New Brunswick, New Jersey, Prof. Lockwood exhibited a thread-worm which, he said, was sent him by a student of Rutgers College, two years ago, who found it in an apple which he was eating. It looked so like an animal parasite that the professor was puzzled to fix its character. He stated that Prof Leidy had recently described before the Academy of Natural Sciences, at Philadelphia, the same worm, also taken from an apple; who also said that this worm was a parasite of the larva of the codling moth, whose grub, or larva, as is well known, infests the young apple, feeding inside of it, and thus causing it to fall from the tree to the ground, when the larva leaves the fruit and enters the ground, in which to pass its pupa state. Thus the worm, whose name is Mermis acuminata, was really an animal parasite, sustaining its own life apparently by a vegetable diet, after the death of the larva codling, either by absorption, or its own consumption of it. Dr. Leidy called the attention of the Academy to the fact that twenty-five years ago he described before them the same entozoön taken from the mouth of a child. At that time he was ignorant of the origin of the parasite. It now seems fair to infer that the child had been eating an infested apple, and that the worm had a second time changed its nidus for that of the child's mouth.
Summer Temperature of Scotland.—Mr. McNab, Director of the Edinburgh Botanic Garden, last year published some facts going to show that the mean summer temperature of Scotland has been growing colder during the last two or three generations. According to Mr. McNab, sundry plants which thrived in Scotland fifty or seventy-five years ago can now scarcely be grown there. Mr. William Tillery communicates to the Gardener's Chronicle several other facts confirmatory of McNab's conclusions. Forty years ago, nearly all the gardens of note in South Ayrshire used to exhibit at the horticultural shows peaches and nectarines grown on walls in the open air. Some good white and black figs were likewise ripened on the open walls in favorable summers; but this is of very rare occurrence now. At the present time, gardeners in the most favored districts of Scotland and in Northern and Midland England are lamenting the unproductive state of their peach and nectarine trees in the open air. A weather-register, kept for the last thirty-eight years, shows that of late years the winters have been more open, the frosts in the spring months later and more severe, and the rainfall more irregular, than formerly.
International Weather Reports.—It has been proposed to establish an exchange of telegraphic weather reports between the Signal-Office at Washington and the meteorological bureaus of the various countries of Europe, and it is claimed that such exchange would be likely to afford valuable data for forecasting the weather on both sides of the Atlantic. Mr. W. Clement Ley, who has worked for a considerable time at the comparison of United States with European weather-charts, holds that such exchange would be undesirable for Europe, on the following grounds: 1. Only a small proportion of the storms experienced on the American side of the Atlantic can subsequently be distinctly traced in Europe at all. 2. Of those thus traceable, the majority are felt severely only in the extreme north of Europe, and are not productive of serious results on the coasts of Britain, France, or Denmark. 3. The velocity of their progress varies indefinitely, and could not be deduced from the velocity of the currents experienced in them, even if the latter were not variable also. 4. Many of the most destructive European storms occur when pressures over the Eastern United States coast are tolerably high and steady. In such instances attention to the telegrams would in all probability mislead. In conclusion, Mr, Ley says: "The connection between the weather periods on the two sides of the Atlantic is one of the problems which the progress of research is steadily, though slowly, attacking. But such research can be carried on without embarking on a system of weather telegraphy, which is unlikely to be practically beneficial, and the failure of which might rather tend to bring this branch of the science into disrepute."
Where do the Grasshoppers belong?—Prof. Riley's Seventh Report contains most valuable facts relative to the natural history and geographical distribution of the grasshopper (Caloptemis spretus) which has caused so much human suffering by its destruction of crops in the Western part of this country. It appears, from the Report, that the late Mr. Walsh, State Entomologist of Illinois, had previously predicted that the insect would not reach the Mississippi River, and, so far as known, subsequent facts bear out the statement, although the reasons stated for the limitation of the species to its present territory are not entirely satisfactory. Prof. Riley exclaims (pp. 165, 166): "Well is it for the people of Missouri, well is it for the people of the Mississippi Talley generally, that this insect cannot go on multiplying indefinitely in their fertile fields. Else, did it go on multiplying and thriving as the Colorado potato-beetle has done, this whole valley would soon become a desert waste. A wise Providence has decreed thus far it shall go and no farther." To the "wisdom" of this "Providence" the poor people of Kansas, Nebraska, etc., may well object, and very naturally withhold their approval from Prof. Riley's biblical rhetoric. It would rather seem, also, from Prof. Riley's map of the portion of Missouri overrun already by the grasshopper, that all the citizens of that State cannot agree that it is "well with them;" but some must be even content to share in the suffering of the farmers of Kansas and Nebraska. As to the "valley of the Mississippi," an inquiry as to the probability of cotton-fields and sugar-plantations affording the proper kind of food for the grasshopper will be in order before Southerners may consider themselves as the chosen people of Prof. Riley's geographically discriminating "Providence." The fact that the cotton-worm (Aletia argillacea) migrates as far north as Canada, though not breeding beyond the limits of the growth of the cotton-plant, would show the possibility of the grasshopper exceeding its present range in favorable seasons, and in localities where the food and soil are congenial.—A. R. Grote.
Social Feeling in Dogs.—A correspondent furnishes the following statement, for the truth of which he vouches: "A gentleman residing a few miles from Brooklyn, on Long Island, had recently two dogs which for several years had shown marked attachment for each other. One day he noticed that one of the dogs was ill, and the following morning found him dead in the barn, where he was accustomed to sleep. The other dog, which slept in the house, left in the morning when the gentleman went out, lively and playful as usual, and on the barn-door being opened bounded in, and saw his companion dead on the floor. Having smelt of him, he looked at him intently for more than a minute, and started for the house, with drooped ears and tail, evidently in distress—certainly he knew that a great change had taken place in his companion. At breakfast the dog refused food, nor did he eat thereafter; his usual cheerfulness gave place to melancholy, and in a few days he died."
A Curions Fog.—Dr. R. Angus Smith describes, in a recent pamphlet, a peculiar sort of fog observed by him in Iceland. On a bright July afternoon Dr. Smith happened to be in Reikjavik, and saw a cloud coming down the street from the southward. Finding that it moved very slowly along the ground, he concluded that it was smoke from a chimney, but smoke mixed with larger particles than are usually seen. When the fog reached the spot where the observer stood, it was found to be devoid of smell, but its influence was decidedly frigorific. Perceiving that it was a fog, Dr. Smith ascended a rising ground, and saw the fog coming from a small lake behind the town, and rolling into the streets very slowly. A similar fog rose from the sea, and rolled, also, into the town. Hence it appeared that the wind had nothing to do with the matter, but that both fogs rolled because they were too heavy to remain suspended. The peculiarity of the fog was in the size of its particles, larger than any the author had ever before seen, and which he estimated at from 1⁄40 to 1⁄300 of an inch in diameter; another peculiarity was its lumbering mode of rolling, in which it resembled dust. The author found that the particles were perfectly spherical, and not hollow, but concrete throughout.
Food-Rations of the French People.—A Very curious calculation has been made by M. Hervé Mangon to determine the average ration per kilogramme of live weight consumed by the rural population of France. He estimates the "live weight" of the French people in 1861 at 1,771,142,951 kilogrammes (say 3,896,514,492 lb.). But these figures, though they represent fairly enough the total weight of the population, cannot serve as a basis for estimating the amount of food required. Children consume more food, in proportion to their weight, than adults. Hence, the author was obliged to express the weight of children, not as it actually was, but in terms corresponding to their consumption of food. In this way he finds the total weight of the French population to be, from the point of view of nitrogen-consumption, 2,112,978,201 kilogrammes (4,648,552,042 lb.), and from the point of view of carbon-consumption 2,095,886,031 kilogrammes (4,610,949,268 lb.). The food annually consumed in France contains carbon 4,434,716,270 kilogrammes (9,756,375,794 lb.); nitrogen 215,724,211 kilogrammes (474,593,264 lb.). If, now, we divide the sum of the carbon and nitrogen by 365 days and then divide the quotient by the total weight of the population, we find the mean daily rations per kilogramme (21⁄2 lb.) of live weight to be, carbon, 5.1797 grammes (77.7533 grains); nitrogen, 0.280 gramme, (4.3212 grains). This is the daily ration per kilogramme for the whole population.
In Paris the daily ration per "live kilogramme" contains 5.675 grammes of carbon, and 0.332 gramme of nitrogen. Supposing, now, that the daily consumption per kilogramme is the same in Paris, Lyons, Marseilles, and the six other cities whose population exceeds 100,000 souls, the mean daily ration per kilogramme of weight for the country districts is found to contain, of carbon 5.808 grammes, and of nitrogen 0.275 gramme. This ration M. Mangon considers to be sufficient to fit the body for a moderate amount of labor; but it would be good economy, he holds, for employers to give their servants and workmen more abundant food. The dullness and slowness of country people he regards as the natural result of insufficient food.
Relations of Meteorology to Life.—At a recent meeting of the British Meteorological Society a communication from the Council was read, entitled "Suggestions of the Observation of Periodic Natural Phenomena," the object being to call attention to those phenomena manifested by organized beings of the vegetable and animal kingdoms dependent on the progression of the seasons, such as the budding, leafing, flowering, fruiting, and the shedding of leaves of trees, shrubs, and herbaceous plants; the earliest and latest appearance of insects; the times at which birds pair and build, and of the arrival and departure of birds of passage; the periods of hibernation of reptiles and small animals, as frogs, dormice, etc. All these phenomena being closely connected with the annual progression of the meteorological elements, are calculated to afford information of the progression of the seasons, of a much more interesting character than that derived from the indication of instruments. Plants are very susceptible of atmospheric influences, and a close correlation exists between the development of plant and animal life as the sun advances in his yearly course, each season being marked by its characteristic phenomena.
The Marriage of Cousins.—The influence of marriage of first cousins on the mental constitution of the offspring is almost universally pronounced to be deleterious. This subject has been treated by Mr. George H. Darwin in a paper read at a meeting of the London Statistical Society. Mr. Darwin's method of obtaining facts upon which to base an induction was by diligent study of Burke's "Peerage," and by sending out circulars of inquiry to members of the upper and middle classes, and to directors of asylums for the insane. Tke result showed that insanity, idiocy, and deaf-muteness, are in the United Kingdom about evenly divided, pro rata, among the progeny of consanguineous and of unconsanguineous marriages; that is to say, Mr, Darwin's investigations have failed to show any evil accruing from the marriages of first cousins. Mr. Darwin acknowledges that the opinion of prominent medical men is against such intermarriages, and that a general consent of physicians possesses far greater weight than his own purely negative results, "My paper," he adds, "is far from giving any thing like a satisfactory solution of the question as to the effects of consanguineous marriages, but it does, I think, show that the assertion that this question has already been set at rest cannot be substantiated. The subject still demands attention, and I hope that my endeavor may lead more competent investigators to take it up from some other side."
A New Ornamental Evergreen. — The myrtle-tree of Oregon attains a height of from twenty to fifty feet, and a diameter of from six to twenty inches. Dr. F. S. Matteson, who describes this beautiful tree, in the Boston Journal of Chemistry, says that it is an evergreen of very full foliage, with leaves three inches long and half as broad, of a deep shining green color; they are delightfully fragrant. The wood is hard, heavy, fine-grained, and takes a high polish; when varnished it is of a dark, variegated color, and is scarcely inferior to rosewood. The tree is very tenacious of life, sprouts freely from the stump after the tree is felled, and is a vigorous, upright grower. It blossoms in early spring, and the best honey in the world is gathered by bees which work in the myrtle-groves. Settlers are cutting down these groves for lumber and fuel, and the timber is burned in heaps to clear the land, Many trees are left standing for the sake of ornament. The nuts afford good food for swine. This tree must certainly become a leading evergreen for ornamentation, as it is unsurpassed by any known tree for all the qualities which make an evergreen desirable, Dr. Matteson thinks it probable that a highly-fragrant oil, useful as a perfume, and perhaps for medical purposes, may be distilled from the leaves.
American Origin of the Chinese. — The colonization of the American Continent from the "Old World," so called, is one of the commonplaces of historical speculation; the colonization of a large portion of the "Old World" from America is a theory of more recent origin, and yet perhaps as plausible as the one which it is intended to supplant. At a meeting of the California Academy of Sciences, Mr, Charles Wolcott Brooks read a paper on the "Origin of the Chinese Race," in which he very learnedly set forth the evidence of their American origin. The author's thesis is supported by a great multitude of facts, but the space at our command will admit only of the barest outline of his argument. According to Chinese annals, Tai Ko Fokee, the great stranger king, ruled the kingdom of China, In pictures he is represented with two small horns, like those associated with the representations of Moses. He and his successor are said to have introduced into China "picture-writing," like that in use in Central America at the time of the Spanish conquest. He taught the motions of the heavenly bodies, and divided time into years and months; he also introduced many other useful arts and sciences.
Now, there has been found at Copan, in Central America, a figure strikingly like the Chinese symbol of Fokee, with his two horns, and in like manner there is a close resemblance between the Central-American and the Chinese figures representing earth and heaven. Either one people learned from the other, or both acquired these forms from a common source, Many physico-geographical facts favor the hypothesis that they were derived in very remote ages from America, and that from China they passed to Egypt. Chinese records say that the progenitors of the Chinese race came from across the sea, But the Pacific is a wide ocean to cross, and favoring winds must have been taken advantage of to carry the emigrants from shore to shore. Mr. Brooks then explained the action of the southeastern and northeastern trade-winds, and argued that, if large junks started from the coast of Peru and kept before the wind, they would in all probability strike the southern coast of China. America is geologically the oldest continent; if so, why not the first peopled? When in the development of America her progress was sufficient to facilitate emigration, why may she not have given a population to Asia? If the primitive races of this continent have died out and their memorials crumbled away, this is a strong argument in favor of the antiquity of the human race here: in more recent Asia traces still remain of original races.
Respiration and Versification.—The natural rate of respiration is from sixteen to twenty-four breaths per minute, the average being twenty. To this fact Dr. Oliver Wendell Holmes attributes the favor in which the octosyllabic verse is held: that Terse, more exactly than any other, follows the natural rhythm of respiration. Experiments with the poetry of Scott, Longfellow, and Tennyson, show that an average of twenty lines will be read in a minute, so that one respiration will suffice for each line. It is, in fact, so easy of articulation, that it is apt to run into a sing-song. The twelve-syllable line of Drayton's "Polyolbion" is pronounced almost intolerable, on account of its "intensely unphysiological construction," Dr. Holmes's conclusion is, that nothing in poetry or in vocal music is popular that is not calculated with strict reference to the respiratory functions.
Diseases of Artisans.—The diseases incident to the following of various trades are considered in detail by a German physician. Dr. Hirt, in his work "Diseases of Artisans." The effects produced by the inhalation of certain gases are discussed by the author in the second division of his work. With regard to carbonic acid he confirms previous observations of the acute affections produced by it, but he does not find the slightest evidence in favor of chronic intoxication by the constant inhalation of small quantities of the gas. In the processes of beer-brewing, wine-making, distilling and yeast-making, considerable quantities of carbonic acid are given off, but, wherever the ventilation is good, no injurious effects are produced. He appears to have no doubt of the occurrence of chronic poisoning by the action of sulphuretted hydrogen. The symptoms are general weakness, depression and usually total loss of appetite, combined with a feeling of weight on the stomach: the tongue is furred. Bisulphide of carbon, obtained by passing sulphur-fumes over burning coal, and subsequent distillation, is now much used as a solvent of India-rubber. It produces chronic poisoning. The symptoms are, at first, evening headache, and pains in the limbs; sometimes intellectual excitement; often cramps, difficulty of breathing, and increased frequency of the heart's action. After some weeks or months follows a period of depression, heaviness, insensibility of some parts of the skin, diminution of sight, and in some cases of hearing. The bad-smelling gases and effluvia given off from putrefying animal substances are said to be innocuous. The trades exposed to such emanations are tanners, soap-boilers, candle-makers, etc. Workmen get accustomed to the fumes of turpentine, and then such fumes appear to have no injurious effects.