Chapter 9

Cow-hide for the outside is sold at 1s. 8d. per square foot, but the leather sellers frequently have pieces large enough for making a bag which they will sell at a slight reduction, and which answers this purpose as well as cutting a hide. In seaming the bag, take care not to wrinkle it in the clams. The welts in this must reach only to the frame, the same as in the carpet bag; the rest of the seam must be neatly closed and rubbed down, so that it will not be lumpy on the frame. Before turning the bag warm it before the fire, especially if it is cold weather. Glue in the bottom stiffening first, and then the gussets, rubbing them well down with the bone. When these are set, prepare for the operation of framing. Fold one of the sides to get the middle of it, cut a hole for the lock barrel about 1¼ inches from the edge, and press it over. Be careful not to cut it too large or the hole will show. Pierce a hole through the leather for the lock plate, press this tightly on the frame, and clinch the clams underneath, to hold it securely. Make holes for the handle plates and fasten them on in a similar manner. Two slits must be cut near the middle of the other side of bag, about ¾ inch from the edge, for the hasp to go through. This bag must be sewn to the frame all round, and care must be taken that a sufficient fullness is allowed in the middle of the gusset to enable it to close easily round the joints of the frame. A thumbpiece must be sewn on the bag at the hasp to open it by. The lining of this bag is sewn through the frame all round in the same manner as the side linings of the carpet bag.

I hope my readers will not think that I have gone too much into details. It is in small things that so many failures take place. As it is much easier to do anything when you are shown than when so much has to be guessed, it is my desire to make the road for beginners as smooth as possible, which must be my excuse if any is required. It is as well that those who intend to turn their attention to working in leather should begin by making a bag; the experience gained in cutting, fitting, putting together, and finishing will be useful when larger and more difficult pieces of work are undertaken.--_Amateur Mechanics._

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MOLASSES, HOW MADE.

The _New England Grocer_ says that the manufacture of molasses is really the manufacture of sugar up to a certain stage, for molasses is the uncrystallized sirup produced in the making of sugar. The methods of manufacture in the West Indies vary very considerably. In the interior and on the smaller plantations it is made by a very primitive process, while on the larger plantations all the appliances of modern science and ingenuity are brought to bear. Each planter makes his own sugar. It is then carried to the sea coast and sold to the exporters, by whom it is shipped to this country. The quality and grade of the molasses varies with each plantation. Two plantations side by side may produce entirely different grades. This is owing to the soil, which in Porto Rico and other localities in the West Indies seems to change with almost every acre. The cane from which the sugar and molasses is made is planted by laying several pieces of it in holes or trenches. The pieces are then covered with earth to the depth of two or three inches. In about two weeks sprouts appear above the surface. Then more earth is put in, and as the sprouts grow, earth is added until in three or four months the holes are filled up. The planting is done from August to November, and the cutting progresses throughout the greater part of the year. The cane grows to a height of seven or eight feet, in joints each about a foot long.

When the cane is in proper condition for cutting, as shown by its appearance, an army of workmen take possession of the field. Each is armed with a long, broad knife, like a butcher's cleaver. They move down the lines of cane like an army, and while the cutting is going on the fields present an interesting sight, the sword-like knives flashing in the sun, the 300 or 400 laborers, the carpet of cut cane, the long line of moving carts, and the sea of standing cane, sometimes extending for miles and miles, stirred by the breeze into waves of undulating green. The laborers employed on these plantations are largely negroes and Chinese coolies. When the cane is ripe, they proceed to the field, each armed with a _matchet_. Spreading over the plantation, they commence the cutting of the cane, first by one cut at the top, which takes off the long leaves and that part which is worthless, except as fodder for the cattle. A second cut is then given as near the root as possible, as the nearer the ground the richer the cane is in juice. The cut cane is allowed to fall carelessly to the ground.

Other workmen come with carts, pick it up, tie it in bundles and carry it to the mill. The cutting of the cane is so adjusted as to keep pace with the action of the mill, so that both are always at work. Two gangs of men are frequently employed, and work goes on far into the night during the season, which lasts the greater part of the year.

As before stated, some of the methods of manufacture are very simple. In the simplest form, the sugar cane is crushed in a mortar. The juice thus extracted is boiled in common open pans. After boiling a certain length of time, it becomes a dark colored, soft, viscid mass. The uncrystallized sirup is expressed by putting the whole into cloth bags and subjecting them to pressure. This is molasses in a crude state. It is further purified by reboiling it with an addition of an alkaline solution and a quantity of milk. When this has continued until scum no longer arises, it is evaporated and then transferred to earthen jars. After it has been left for a few days to granulate, holes in the bottom of the jars are unstopped, and the molasses drains off into vessels placed to receive it. Another process of extracting molasses is as follows: By various processes of boiling and straining, the juice is brought to a state where it is a soft mass of crystals, embedded in a thick, but uncrystallized, fluid. The separation of this fluid is the next process, and is perfected in the curing house, so called. This is a large building, with a cellar which forms the molasses reservoir. Over this reservoir is an open framework of joists, upon which stands a number of empty potting casks. Each of these has eight or ten holes bored through the bottom, and in each hole is placed the stalk of a plantain leaf. The soft, concrete mass of sugar is removed from the cooling pans in which it has been brought from the boilers and placed in the casks. The molasses then gradually drains from the crystallized portion into the reservoir below, percolating through the spongy plantain stalks.

On the larger plantations, machinery of very elaborate description is used, and the most advanced processes known to science are employed in the manufacture. The principle is, however, the same as has been seen in the account of the simpler processes. On these larger plantations there are extensive buildings, quarters for workmen, steam engines, and all the necessary adjuncts of advanced manufacturing science. In the sugar mills the cut cane is carried in carts to the mill. It is then thrown by hand upon an endless flexible conductor which carries the cane between heavy crushers. The great jaws of the crushers press the cane into pulp, when it is thrown aside automatically to be carted away and used as a fertilizer. The juice runs off in the channels of the conductor into huge pans. The juice is now of a dull gray color and of a sweet, pleasant taste, and is known as _guarapo_. It must be clarified at once, for it is of so fermentable a nature that in the climate of Porto Rico it will run into fermentation inside of half an hour if the process of clarifying is not commenced. The pans into which the juice is conducted are pierced like a colander. The liquor runs through, leaving the refuse matter behind. It is then forced into tanks by a pump and run to the clarifiers, which are large kettles heated by steam. Lime is used to assist the clarification. It is then filtered into vats filled with bone black. The filtering is repeated until the juice changes color, when it is conveyed to the vacuum pans. It has now become a thick sirup. It is then pumped into the sirup clarifiers, skimmed, and again run through bone black, and finally is conducted into another kettle, where it is allowed to crystallize. The sirup that fails to crystallize is molasses, and it is here that we catch up with what we started after. To extract the molasses from the crystallized mass of sugar, we must go to the purging house. This is similar to the building spoken of in connection with the simpler process. It is of two stories. The upper floor is merely a series of strong frames with apertures for funnel-shaped cylinders. The sugar is brought into the purging house in great pans, which are placed over the funnels. The pans are pierced with holes through which the molasses drains off into troughs which are underneath the floor, all running to a main trough. From thence the molasses runs into vats, called _bocoyes_, each of which holds from 1,200 to 1,500 gallons. The hogsheads in which the molasses is brought to this country are manufactured principally in Philadelphia and taken to the West Indies. They are placed in the hold of the vessel and the molasses pumped into them. The government standard for molasses is 56 degrees polarization. When not above that test, the duty is four cents per gallon. Above it the duty is eight cents. This tends to keep molasses pure, as the addition of glucose increases the quantity of sugar and therefore of the polarization, and would make necessary the payment of increased duties. The adulteration of molasses is therefore largely if not wholly done after it is out of bond and in the hands of the jobber.

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PRIMITIVE IRON MANUFACTURE.

We are indebted for the illustrations and the particulars to Dr. Percy's invaluable book on iron and steel (probably it is not saying too much to describe it as the best work on the subject ever written).

Fig. 1 shows a sectional elevation, and Fig. 2 shows a plan of furnace and bellows and tuyeres, indeed, an entire ironworks plant used in India, not only now, but, so far as we can gather, from time immemorial. The two figures give a sufficiently clear idea of the form of furnace used in Lower Bengal, in which portion of our Indian empire there are entire villages exclusively inhabited by iron smelters, who, sad to relate, are distinguished from the agricultural villages surrounding them by their filth, poverty, and generally degraded condition. There are whole tribes in India who have no other occupation than iron smelting. They, of course, sink no shafts and open no mines, and are not permanent in any place. They simply remain in one place so long as plentiful supplies of ore and wood are obtainable in the immediate vicinity. In many cases the villages formerly inhabited by them have passed out of existence, but the waste, or rather wasted products, of their operations remain.

The furnace shown in Figs. 1 and 2 is built of the sandy soil of the district, moistened and kneaded and generally strengthened by a sort of skeleton of strips of flexible wood. In form it varies from a cylinder, more or less circular, diverging into a tolerably acute cone, the walls being about 3 in. thick. The height is generally about 3 ft. and the mean internal diameter about 1 ft., but all these dimensions vary with different workmen and in different localities. There are two apertures at the base of the furnace; one in front, about 1 ft. in height, and rather less in width than the internal diameter of the furnace, through which, when the smelting of one charge is finished, the resulting mass of spongy iron is extracted, and which during the smelting is well plastered up, the small conical tuyere being inserted at the bottom. This tuyere is usually made of the same material as the furnace--namely, of a sandy soil; worked by hand into the required form and sun-dried; but sometimes no other tuyere is employed than a lump of moist clay with a hole in it, into which the bamboo pipes communicating with the bellows are inserted. The other aperture is smaller, and placed at one side of the furnace, and chiefly below the ground, forming a communication between the bottom of the furnace chamber and a small trench into which the slag flows and filters out through a small pile of charcoal. It is this slag being found in places where iron is not now made that shows that iron smelting was an occupation there, perhaps many centuries before.

The inclined tray shown at the top of the furnace on Fig. 1 is made of the same material as the furnace itself, and when kneaded into shape is supported on a wooden framework. On it is piled a supply of charcoal, which is raked into the furnace when required.

The blowing apparatus is singularly ingenious, and is certainly as economical of manual labor as a blowing arrangement depending on manual labor well can be. A section of the bellows forms the portion to the right of Fig. 1, showing tuyere forming the connection between bellows and furnace. It consists of a circular segment of hard wood, rudely hollowed, and having a piece of buffalo hide with a small hole in its center tied over the top. Into this hole a strong cord is passed, with a small piece of wood attached to the end to keep it inside the bellows, while the other end is attached to a bent bamboo firmly fixed into the ground close by. This bamboo acts as a spring, drawing up the string, and consequently the leather cover of the bellows, to its utmost stretch, while air enters through the central hole. When thus filled, a man places his foot on the hide, closing the central hole with his heel, and then throwing the whole weight of his body on to that foot, he depresses the hide, and drives the air out through a bamboo tube inserted in the side and communicating with the furnace. At the same time he pulls down the bamboo with the arm of that side. Two such bellows are placed side by side, a thin bamboo tube attached to each, and both entering the one tuyere; and so by jumping on each bellows alternately, the workman keeps up a continuous blast.

The Figs. 1 and 2 are taken from sketches, and the description from particulars, by Mr. Blandford, who was for some years on the Geological Survey of India, and had exceptional opportunities in his journeyings of observing the customs and occupations of the Indian iron smelters. The blowing machine is an especially wonderful and effective machine, and was first described and illustrated by Mr. Robert Rose, in a Calcutta publication, more than half a century ago. He also had seen it used in iron making in India.--_Colliery Guardian._

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WOOD OIL.

Wood oil is now made on a large scale in Sweden from the refuse of timber cuttings and forest clearings, and from stumps and roots. Although it cannot well be burned in common lamps, on account of the heavy proportion of carbon it contains, it is said to furnish a satisfactory light in lamps specially made for it; and in its natural state it is the cheapest illuminating oil. There are some thirty factories engaged in its production, and they turn out about 40,000 liters of the oil daily. Turpentine, creosote, acetic acid, charcoal, coal-tar oils, etc., are also obtained from the same materials as the wood oil.

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SOAP.

By HENRY LEFFMANN, M.D.

Although the use of soap dates from a rather remote period, the chemist is still living, at an advanced age, to whom we are indebted for a knowledge of its composition and mode of formation. Considerably more than a generation has elapsed since Chevreul announced these facts, but a full appreciation of the principles involved is scarcely realized outside of the circle of professional chemists. Learned medical and physiological writers often speak of glycerin as the "sweet principle of fats," or term fats compounds of fatty acids and glycerin. Indeed, there is little doubt that the great popularity of glycerin as an emollient arose from the view that it represented the essential base of the fats. With regard to soap, also, much erroneous and indistinct impression prevails. Its detergent action is sometimes supposed to be due to the free alkali, whereas a well-made soap is practically neutral.

A desire to secure either an increased detergent, cleansing, or other local effect has led in recent years to the introduction into soaps of a large number of substances, some of which have been chosen without much regard to their chemical relations to the soap itself. The result has been the enrichment of the materia medica with a collection of articles of which some are useful, and others worse than useless. The extension of the list of disinfectant and antiseptic agents and the increased importance of the agents, in surgery, have naturally suggested the plan of incorporating them with soaps, in which form they will be most convenient for application. Accordingly, the circulars of the manufacturing pharmacists have prominently displayed the advantages of various disinfecting soaps.

Among these is a so-called corrosive sublimate soap, of which several brands are on sale. One of these, containing one per cent. of corrosive sublimate, is put on the market in cakes weighing about sixteen hundred grains, and each cake, therefore, contains sixteen grains of the drug--a rather large quantity, perhaps, when it is remembered that four grains is a fatal dose. Fortunately, however, for the prevention of accidents, but unfortunately for the therapeutic value of the soap, a decomposition of the sublimate occurs as soon as it is incorporated in the soap mass, by which an insoluble mercurial soap is formed. This change takes place independently of the alkali used in the soap; in fact, as mentioned above, a well-made soap contains no appreciable amount of free alkali, but is due to the action of the fat acids. Corrosive sublimate is _incompatible_ with any ordinary soap mass, and this incompatibility includes not only other soluble mercurial salts, but also almost all the mineral antiseptics, such as zinc chloride, copper sulphate, iron salts. Some of the preparations of arsenic may, however, be incorporated with soap without decomposition.

Such being the chemical facts, we must admit that no reliance can be placed in corrosive sublimate soaps as germicide agents. It must not be supposed that this incompatibility interferes with the use of these soaps for general therapeutic purposes. It is only the specific germicide value which is destroyed. Since the fats used in soap manufacture yield oleic acid, we will have a certain amount of mercuric oleates formed together with stearate and other salts, and for purposes of inunction these salts might be efficient. Still the physician would prefer, doubtless, to use the specially prepared mercurial.

In producing, therefore, a disinfecting soap, being debarred from using the metallic germicides, we are fortunate in the possession of a number of efficient agents, organic in character, which may be used without interference in soaps.

Among these are thymol, naphthol, oil of eucalyptus, carbolates, and salicylates. There is no chemical incompatibility of these with soap, and as they are somewhat less active, weight for weight, than corrosive sublimate, they are capable of use in larger quantities with less danger, and can thus be made equally efficacious.

It is in this direction, therefore, that we must look for the production of a safe and reliable antiseptic soap.

There is not much exact knowledge as to the usefulness of such additions to soap as borax and glycerin. They are frequently added, and highly spoken of in advertisements. Borax is a mild alkaline body, and as a detergent is probably equivalent to a slight excess of caustic soda. Glycerin, although originally considered an emollient, probably on account of its source and physical properties, is in reality, to some skins at least, a slight irritant. It is, in fact, an alcohol, not a fat. It does not pre-exist in fats, but is formed when the fat is decomposed by alkali or steam.

In ordinary cases, soap owes its detergent effect to a decomposition which occurs when it is put in water.

A perfectly neutral soap, that is, one which contains the exact proportion of alkali and fat acid, will, when placed in cold water, decompose into two portions, one containing an excess of the acid, the other an excess of alkali. The latter dissolves, and gives a slightly alkaline solution; the former precipitates, and gives the peculiar turbidity constituting "suds." These reactions must be kept in mind in determining the effect of the addition of any special substance to the soap.--_The Polyclinic._

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OPTICAL ERRORS AND HUMAN MISTAKES.[1]

[Footnote 1: Read before the American Association, Buffalo, August, 1886.]

By ERNST GUNDLACH.

I wish to call attention to a few mistakes that are quite commonly made by microscopists and writers in stating the result of their optical tests of microscope objectives.

If the image of an object as seen in the microscope appears to be unusually distorted and indistinct toward the edge of the field, and satisfactory definition is limited to a small portion of the center, the cause is often attributed to the spherical aberration of the objective, while really this phenomenon has nothing to do with that optical defect of the objective, if any exists, but is caused by a lack of optical symmetry. If a perfectly symmetrical microscope objective could be constructed, then, with any good eye-piece, it would make no difference to the definition of the object were it placed either in the center or at the edge of the field, even if the objective had considerable spherical aberration. But, unfortunately, our most symmetrical objectives, the low powers, leave much to be desired in this respect, while our wide angle, high powers are very far from symmetrical perfection.

There are two causes of this defect in the latter objectives, one being the extreme wideness of their angular apertures, and the other the great difference in the distances of the object and the image from the optical center of the objectives.