Chapter 8

[Footnote 2: The period of a wave is the interval of time which elapses between the transits of two successive wave crests past a stationary floating body, the wave crest being the highest line along the ridge.]

It is the opinion of scientists that when the period of oscillation of the ship and the period of the wave are nearly the same, the turning over of the ship is an approximate consequence, and thus the wave to such a ship would appear more formidable than to another ship with a different period of oscillation.--_Nautical Magazine._

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PRACTICAL EDUCATION.

It is now recognized that one of the elements in which the public school systems of the United States are most lacking is in the practical branches in teaching trades and industry. There is too much book learning, too little practical education. Throughout the continent of Europe there are trade and industrial schools which have accomplished much in turning out skilled workmen for the various branches of industry. Here we have one. Our deficiency in this matter was recognized by the late commissioner of education, and attention called to it in several of his reports, and a number of the State superintendents of education have also urged the establishment of manual or training schools as a part of the State systems. We have such an institution here in the Tulane Manual School. In Philadelphia, Cleveland, and Chicago, the system has been adopted on a large scale, and made part of the high school course. Another city which has inaugurated the manual training school as a part of its public schools is Toledo, O. A rich citizen of that town, who recently died, left a large sum for the establishment of a university of arts and trades. Instead of founding a separate university, however, the money was applied to the establishment of manual schools in connection with the public schools, for both boys and girls.

The course of girls' work given will afford some idea of what it is proposed to do. This begins with the senior grammar school grade and continues three years in high school. It includes free hand, mechanical, and architectural drawing, light carpentry, wood carving, designing for wood carving, wood turning, clay moulding, decorative designing, etc. But more practical than these things are the lessons in cooking, sewing, and household management. The course in domestic economy "is arranged with special reference to giving young women such a liberal and practical education as will inspire them with a belief in the dignity and nobleness of an earnest womanhood, and incite them to a faithful performance of the every day duties of life. It is based upon the assumption that a pleasant home is an essential element of broad culture, and one of the surest safeguards of morality and virtue." The report of the school also remarks that "the design of this course is to furnish thorough instruction in applied housekeeping, and the sciences related thereto, and students will receive practical drill in all branches of housework; in the purchase and care of family supplies, and in general household management; but will not be expected to perform more labor than is actually necessary for the desired instruction."

A special branch which will be well received is that which proposes to teach the girls how to cook. The curriculum is one that every housekeeper ought to go through.

Boiling--Practical illustrations of boiling and steaming, and treatment of vegetables, meats, fish, and cereals, soup making, etc.

Broiling--Lessons and practice in meat, chicken, fish, oysters, etc.

Bread Making--Chemical and mechanical action of materials used. Manipulations in bread making in its various departments. Yeasts and their substitutes.

Baking--Heat in its action on different materials in the process of baking. Practical experiments in baking bread, pastry, puddings, cakes, meat, fish, etc.

Frying--Chemical and mechanical principles involved and illustrated in the frying of vegetables, meats, fish, oysters, etc.

Mixing--The art of making combinations, as in soups, salads, puddings, pies, cakes, sauces, dressings, flavorings, condiments, etc.

In "marketing, economy," etc., the course comprises general teaching on the following subjects:

"The selection and purchase of household supplies. General instructions in systematizing and economizing the household work and expenses. The anatomy of animals used as food, and how to choose the several parts. Lessons on the qualities of water and steam; the construction of stoves and ranges; the properties of different fuels."

Again, there is a dressmaking and millinery department, where the girls are taught how to cut and make dresses and other garments, and the economical and tasteful use of materials.

So much for the girls. The courses in the boys' schools are somewhat similar, turning, however, on the more practical instruction in trades and industries, in carpentering, wood and iron work, etc.

The Toledo experiment has been tried there but one year, and has given general satisfaction. The board of school directors has interested the public in its efforts, and advisory committees of ladies and gentlemen have been appointed to assist in managing these schools.

It is to be hoped that other and larger cities will imitate Toledo in the matter. Those philanthropists who are giving money so liberally for the establishment of institutions of higher learning might do much good in providing for manual training schools of this kind that will assure the country good housewives and skilled mechanics in the future.--_Trustees' T. Jour._

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A GIGANTIC LOAD OF LUMBER.

When it was announced in the _Lumberman_ that the barge Wahnapitæ had carried a cargo of 2,181,000 feet of lumber, letters were received asking if it was not a typographical error. It was thought by many that no boat could carry such a load. For the purpose of showing the barge on paper, a photograph was obtained of her when loaded at Duluth, which is herewith reproduced. The freight rate obtained to Tonawanda was $3.75 a thousand, which footed up to a total of $8,178.75 The owners of the boat, however, were not satisfied with such a record, and proceeded to break it by loading at Duluth 2,409,800 feet of lumber, which also went to Tonawanda, and which is put down as the biggest cargo of lumber on record. At the latter place the cargo was unloaded on Saturday afternoon and Monday forenoon--one working day. It will be readily understood that the money-making capacity of the barge is of the Jumbo order also.

The barge is owned by the Saginaw Lumber and Salt Company and the Emery Lumber Company, and cost $30,000. She is 275 feet long and 51 feet beam. The lumber on her was piled 22 feet high and she drew 11 feet of water. Had she been 10 inches wider, she could not have passed through the Soo canal. The boat was built on the Saginaw river a year ago last winter, and was designed for carrying logs from the Georgian bay to the Saginaw river and Tawas mills. The Canadian government, however, increased the export duty on logs, and the barge was put into the lumber-carrying trade--_N.W. Lumberman._

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THE NEWBERY-VAUTIN CHLORINATION PROCESS.

The process of extracting gold from ores by absorption of the precious metal in chlorine gas, from which it is reduced to a metallic state, is not a very new discovery. It was first introduced by Plattner many years ago, and at that time promised to revolutionize the processes for gold extraction. By degrees it was found that only a very clever chemist could work this process with practically perfect results, for many reasons. Lime and magnesia might be contained in the quartz, and would be attacked by the chlorine. These consume the reagents without producing any results, earthy particles would settle and surround the small gold and prevent chlorination, then lead and zinc or other metals in combination with the gold would also be absorbed by the chlorine; or, again, from some locally chemical peculiarity in the water or the ore, gold held in solution by the water might be again precipitated in the tailings before filtration was complete, and thus be lost. Henderson, Clark, De Lacy, Mears, and Deacon, all introduced improvements, or what were claimed to be improvements, on Plattner, but these chiefly failed because they did not cover every particular variety of case which gold extraction presented. Therefore, where delicate chemical operations were necessary for success, practice generally failed from want of knowledge on the part of the operator, and many times extensive plants have been pronounced useless from this cause alone. Hence it is not to be wondered that processes requiring such care and uncommon knowledge are not greatly in favor.

Mr. Claude Vautin, a gentleman possessed of much practical experience of gold mining and extraction in Queensland, together with Mr. J. Cosmo Newbery, analytical chemist to the government of Victoria, have developed a process which they claim to combine all the advantages of the foregoing methods, and by the addition of certain improvements in the machinery and mode of treatment to overcome the difficulties which have hitherto prevented the general adoption of the chlorination process.

By reference to the illustrations of the plant below, the system by which the ore is treated can be readily understood. The materials for treatment--crushed and roasted ore, or tailings, as the case may be--are put into the hopper above the revolving barrel, or chlorinator. This latter is made of iron, lined with wood and lead, and sufficiently strong to bear a pressure of 100 lb. to the square inch, its capacity being about 30 cwt of ore. The charge falls from the hopper into the chlorinator. Water and chlorine-producing chemicals are added--generally sulphuric acid and chloride of lime--the manhole cover is replaced and screwed down so as to be gas tight. On the opposite side of the barrel there is a valve connected with an air pump, through which air to about the pressure of four atmospheres is pumped in, to liquefy the chlorine gas that is generated, after which the valve is screwed down. The barrel is then set revolving at about ten revolutions a minute, the power being transmitted by a friction wheel. According to the nature of the ore, or the size of the grains of gold, this movement is continued from one to four hours, during which time the gold, from combination with the chlorine gas, has formed a soluble gold chloride, which has all been taken up by the water in the barrel. The chlorinator is then stopped, and the gas and compressed air allowed to escape from the valve through a rubber hose into a vat of lime water. This is to prevent the inhalation of any chlorine gas by the workmen. The manhole cover is now removed and the barrel again set revolving, by which means the contents are thrown automatically into the filter below. This filter is an iron vat lined with lead. It has a false bottom, to which is connected a pipe from a vacuum pump working intermittently. As soon as all the ore has fallen from the chlorinator into the filter, the pump is set going, a partial vacuum is produced in the chamber below the false bottom in the filter, and very rapid filtration results. By this means all the gold chlorides contained in the wet ore may be washed out, a continual stream being passed through it while filtration is going on. The solution running from the filter is continually tested, and when found free from gold, the stream of water is stopped, as is also the vacuum pump. The filter is then tipped up into a truck below, and the tailings run out to the waste heap. The process of washing and filtration occupies about an hour, during which time another charge may be in process of treatment in the chlorinator above. The discharge from the filter and the washings are run into a vat, and from this they are allowed to pass slowly through a tap into a charcoal filter. During the passage of the liquid through the charcoal filter, the chloride of gold is decomposed and the gold is deposited on the charcoal, which, when fully charged, is burnt, the ashes are fused with borax in a crucible, and the gold is obtained.

We have specified above the objections to the old processes of chlorination, so it may be fairly asked in what way the Newbery-Vautin process avoids the various chemical actions which have hitherto proved so difficult to contend with.

For any system of chlorination yet introduced it is necessary to free the ore from sulphides. This is done by roasting according to any of the well-known systems in vogue. It is a matter which requires great care and considerable skill. The heat must be applied and increased slowly and steadily. If, through any neglect on the part of the roaster, the ore is allowed to fuse, in most cases it is best to throw the charge away, as waste. This roasting applies equally to the Vautin process as to any others. So on this head there is no alteration. One of the most important advantages is not a chemical one, but is the rapidity with which the charge can be treated. In the older styles of treatment the time varied from thirty six to ninety hours. Now this is accomplished in from three to six hours with a practically perfect result. The older processes required a careful damping of the ore, which, to get good results, must leave the ore neither too wet nor too dry. Now "damping" is entirely done away with, and in its place water is poured into the barrel. Pressure to the extent of four atmospheres causes chlorine gas to leave its vaporous form. Thus the pressure applied not only enables a strong solution of chlorine to be formed with the water in the barrel, but forces this into contact with the gold through every crevice in the ore. Chlorine gas also takes up any silver which may exist in association with the gold. In the older processes this is deposited as a film of chloride of silver around the fine gold grains, and from its insolubility in water prevents the absorption of the gold. The rotary motion of the barrel in the Newbery-Vautin method counteracts this by continually rubbing the particles together; this frees the particles from any accumulations, so that they always present fresh surfaces for the action of the solvent. Again, the short time the ore is in contact with the chlorine does not allow of the formation of hydrochloric acid, which has a tendency to precipitate the gold from its soluble form in the water before being withdrawn from the chlorinator.

Hitherto, when the ore was very fine or contained slimes, the difficulty of filtration was increased, sometimes in extreme cases to such an extent that chlorination became impracticable. By the introduction of the vacuum pump this is greatly facilitated; then by making the action intermittent a jigging motion is given to the material in the filter which prevents any clogging except in cases of extreme fineness.

The advantage of using charcoal as a decomposing agent for chloride of gold was pointed out by Mr. Newbery some twenty years ago; four or five years since the idea was patented in the United States, but as this was given gratis to the world years before, the patent did not hold good. The form of precipitation generally adopted was to add sulphate of iron to the liquid drawn from the filter. This not only threw down the gold it contained, but also the lime and magnesia. Then very great care was necessary, and a tedious process had to be gone through to divide the gold from these. Now, by filtration through charcoal everything that is soluble in hydrochloric acid passes away with the water; for instance, lime and magnesia, which before gave such great trouble. In passing through the charcoal, the chloride of gold is decomposed and all fine gold particles are taken up by the charcoal, so that it is coated by what appears to be a purple film.

Should copper be associated with the gold, the water, after running through the charcoal filter, is passed over scrap iron, upon which the copper is precipitated by a natural chemical action. If silver is contained in the ore, it is found among the tailings in the filter, in a chloride which is insoluble in water. Should the quantity prove sufficiently large, it may be leached out in the usual way by hyposulphites.

One of the great advantages common to all systems of chlorination is that ores may be crushed dry and treated, so that the loss from float gold may be avoided. Of this loss, which is most serious, we shall have something to say on another occasion. An advantage in amalgamation with chlorine gas instead of amalgamation with quicksilver in the wet way, is that the ore need not be crushed so finely. Roasting takes the place of fine crushing, as the ore from the roasting furnace is either found somewhat spongy in texture or the grains of silica in which fine gold may be incased are split or flawed by the fire. For quicksilver amalgamation very fine crushing is necessary to bring all gold particles in contact with it. Quicksilver being so thick in substance, it will not find its way readily in and out of a microscopically fine spongy body or through very fine flaws in grains of silica, whereas chlorine gas or a solution of liquefied chlorine does this, and absorbs the gold far more readily.

There are cases when gold is contained in ores in what is known as a perfectly "free" form--that is, there is an absence of all sulphides, arsenides, etc.--when it is not practicable to extract it either with the ordinary forms of quicksilver amalgamation of or any process of chlorination, without first roasting. This is because the finer gold is locked up inside fine grains of silica and hydrated oxide of iron. No ordinary crushing will bring this fine enough, but when roasting is resorted to by drawing it rapidly through a furnace heated to a cherry red, these grains are split up so that chlorine gas is enabled to penetrate to the gold.

It may be said that an equally clever chemist will be required to work this improved process as compared with those that have, one by one, fallen into disuse, mainly from want of knowledge among the operators. To a certain extent this is so. The natural chemical actions are not so delicate, but an ignorant operator would spoil this process, as he does nearly every other. When a reef is discovered, practice shows that its strongest characteristics are consistently carried throughout it wherever it bears gold. Before Messrs. Newbery and Vautin leave a purchaser to deal himself with their process, they get large samples of his ore to their works and there experiment continually until a practically perfect result is obtained; then any one with a moderate amount of knowledge can work with the formula supplied. It has been their experience that the ore from any two mines rarely presents the same characteristics. Experiments are begun by treating very coarse crushings. These, if not satisfactory, are gradually reduced until the desired result is obtained.

To treat the whole body of ore from a mine, dry crushing is strongly recommended. To accomplish this in the most efficient manner, a stone breaker which will reduce to about ¼ in. cubes is necessary. For subsequent crushing Kroms rolls have, up to the present time, proved most satisfactory. They will crush with considerable evenness to a thirty mesh, which is generally sufficient. The crushings are then roasted in the ordinary way in a reverberatory furnace and the whole of the roastings are passed through the machine we have just described. By this it is claimed that over 90 per cent. of the gold can be extracted at very much the same cost as the processes now in general use in gold producing countries, which on the average barely return 50 per cent. If so, the gentlemen who have brought forward these improvements deserve all the success their process promises.--_Engineering._

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APPARATUS FOR EXERCISING THE MUSCLES.

The apparatus herewith illustrated consists of a wooden base, which may be bolted to the floor, and which supports two wooden uprights, to which is affixed the apparatus designed to exercise the legs. The apparatus for exercising the arms is mounted upon a second frame that slides up and down the wooden supports. It is fixed in position at any height by means of two screws.

The apparatus for exercising the legs, as well as the one for the arms, consists essentially of a fly wheel mounted upon an axle extending to the second upright and bent into the form of a crank in the center. The fly wheel is provided with a winch whose arm is capable of elongation in order to accommodate it to the reach of the sound limb.

The apparatus for the legs is arranged in a contrary direction, that is to say, the wheel is on the opposite side of the frame, and upon the fixed uprights. It is really a velocipede, one of the pedals of which is movable upon the winch, and is capable of running from the axle to the extremity, as in the upper apparatus. This pedal has the form of a shoe, and is provided with two straps to keep the foot in place and cause it to follow the pedal in its rotary motion. A movable seat, capable of rising and descending and moving backward and forward, according to the leg that needs treatment, is fixed back of the apparatus.

The operation is as follows: Suppose that the atrophied arm is the left one. The invalid, facing the apparatus, grasps the movable handle on the crank with his left hand, and revolves the winch with his right. The left hand being thus carried along, the arm is submitted to a motion that obliges it to elongate and contract alternately, and the result is an extension of the muscles which strengthens them.

The apparatus, which is as simple as it is ingenious, can, it is true, be applied only when one of the two limbs, arm or leg, is diseased, the other being always necessary to set the apparatus in motion; but, even reduced to such conditions, it is destined to render numerous services in cases of paralysis, atrophy, contusions, etc.--_Moniteur des Inventions Industrielles._

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THE BULL OPTOMETER.

Dr. Javal has just presented to the Academy of Medicine a very ingenious and practical optometer devised by George J. Bull, a young American doctor, after a number of researches made at the laboratory of ophthalmology at the Sorbonne. Among other applications that can be made of it, there is one that is quite original and that will insure it some success in the world. It permits, in fact, of approximately deducing the age of a person from certain data that it furnishes as to his or her sight. As well known, the organs become weak with age, their functions are accomplished with less regularity and precision, and, according to the expression of the poet,

"_En marchant a la mort, on meurt a chaque pas,_"

the senses become blunted, the hearing becomes dull, the eyes lose their luster, vivacity, and strength, and vision becomes in general shorter, less piercing, and less powerful.

The various parts of the eye, but more particularly the crystalline lens, undergo modifications in form and structure. Accommodation is effected with more and more difficulty, and, toward the age of sixty, it can hardly be effected at all.

These changes occur in emmetropics as well as in hypermetropics and myopics.