APPENDIX I. STUDENT THEMES I. EXPOSITION OUTLINE: THE MANUFACTURE OF MALLEABLE IRON I. Introduction. A. Malleable iron differs from gray or cast iron 1. In its physical qualities; being a. Softer, less brittle, and capable of being beaten out like lead, though in a less degree; b. Much stronger under tension; and c. Much better able to resist a jarring shock. 2. In its chemical composition, since a. The free carbon it contains is amorphous, not graphitici.e. is scattered, minutely divided, through out the mass, not segregated in flakes as in gray iron, and b. There is less sulphur and phosphorus present. B. Two main processes are involved in the manufacture of malleable iron: 1. The making of white iron, and 2. The conversion of this white iron into malleable iron. II. Details of the manufacture. A. Making the white iron. 1. The material used comprises a mixture of a. Pig iron, including (a) Charcoal pig - smelted with charcoal instead of coke as fuel; (b) Malleable Bessemer pig an ordinary pig iron containing less sulphur and phosphorus than the "foundry pig" used in the manufacture of gray iron. b. Scrap iron-consisting of (a) Malleable scrap ings, worn out malleable iron cast (b) Steel scrap - (c) "Sprue" - the waste iron left over from the 2. The material is melted a. In a cupola — a vast hollow cylinder in which the fuel (coke) and the material are placed in alternate layers, the material being melted in direct contact with the fuel, or, preferably, b. In an air-furnace which consists of (a) A fire-box, in which a huge fire is kept up with good gas-coal as fuel, and (b) A melting-hearth, containing the material to be melted. This is separated from the fire-box by a low wall, over which the flame from the fire is driven by a forced draught. B. The annealing process, which converts the white iron into malleable 1. Consists in slowly heating the white iron product (tightly packed with iron oxide in ovens) to a temperature of about 1600° F. and letting it gradually cool down, and 2. Causes great changes in the nature of the iron, as regards a. Its chemical composition - the carbon, which in the white iron has been chemically combined with the metal as iron carbide, being separated out and distributed through the mass in a free form, mechanically mixed with the iron, and b. Its physical qualities, the hard brittle metal first obtained being converted into the soft, strong, and durable product described in the beginning. III. Conclusion. A. It is evident that the double process involved is both complicated and expensive. B. The superior quality of the metal obtained more than repays the difficulties of its manufacture. THE MANUFACTURE OF MALLEABLE IRON THE vast majority of iron castings made to-day are of either malleable or gray iron. We intend in this paper to concern ourselves only with the former; but a brief comparison or rather contrast - of its qualities with those of gray iron will be of great assistance 555 towards the comprehension of the subject. Malleable iron, then, differs from gray iron both in its physical properties and in its chemical composition. It is softer and less brittle, and can be beaten out like lead though, needless to say, to a very much less degree. It is also stronger under tension and better able to resist a jarring shock. These qualities make it in every way the superior metal; it is, indeed, kept from supplanting gray iron entirely only by the fact that it is approximately twice as expensive. The constituent elements in the chemical composition of the two irons are identical; for the analytical chemist a slight difference in the form or proportions of these elements alone distinguishes malleable from gray iron. Each contains about ninety-six per cent of pure iron, mixed or combined with varying proportions of carbon, silicon, sulphur, phosphorus, and manganese. The soft and pliable nature of malleable iron is chiefly due to the state of the free carbon it contains. This is amorphous rather than graphitic; in other words, it is scattered evenly and minutely divided throughout the mass, not segregated in flakes, as in gray iron. The fact that sulphur and phosphorus are present in far smaller quantities also adds considerably to its strength, as those two elements always tend to make the metal more brittle. Such are the qualities of malleable iron. The processes involved in its manufacture are, essentially, two. In the first place, the material is prepared in the form of white iron the hardest and most brittle form of iron known; in the second place, this white iron is converted by a special heat treatment into the finished malleable product. We are first concerned with the making of the white iron. For this, pig iron and scrap iron in almost equal proportions provide the material. The pig used consists of malleable Bessemer pig iron containing less sulphur and phosphorus than the "foundry pig" used in the manufacture of gray iron an ordinary coal pig, which has been melted with charcoal in place of coke as fuel. or, preferably, of charThe superiority of the latter is due to the practically negligible amount of sulphur it contains. Of the scrap iron used, three-fourths consists usually of "sprue," as it is called. This comprises the waste iron left over from the previous day, the metal from the channels in the moulds through which it ran to form the castings, the shop "sweepings," etc. The remaining fourth is made up of equal amounts of malleable scrap worn out malleable iron castings, and steel scrap old steel rails and the like. This material is melted up either in a cupola or an air furnace. The former is a vast hollow cylinder in which the fuel (coke) and the metal are placed in alternate layers. The iron is thus melted in direct contact with the fuel an arrangement by no means desirable, as the metal invariably absorbs a certain amount of sulphur from the coke. The air furnace is a decidedly better arrangement. It comprises a fire-box, in which a huge fire is kept up with good gas-coal as fuel, and a melting hearth containing the material to be melted. The hearth is separated from the fire-box by a low wall, over which the flame is driven by a forced draught. When the material has been melted down in such a furnace and run out into the moulds, it is in the form of white iron, and the first process in the manufacture of the malleable casting is completed. White iron is almost as hard and brittle as glass, but its nature is entirely changed by the simple heat treatment known as annealing. The castings are tightly packed with iron oxide in cylindrical pots of about two feet in depth and diameter - much as one would pack crockery with straw in a barrel, the chief object being to keep them from warping at the high temperature to which they are soon to be subjected. They are next placed in huge ovens and slowly heated to about 1600° F., then gradually allowed to cool down. They stay in the ovens altogether between four and five days. The physical alteration which has taken place in the properties of the metal is evident, but the reasons for the chemical change which takes place at the same time have not yet been definitely discovered. That the carbon, which in the white iron had been chemically combined with the metal as iron carbide, is separated out and distributed through the mass in a free amorphous form mechanically mixed with it, is an indisputable fact. Chemists, however, are not yet agreed as to why the simple heat treatment should produce such a result. Certain it is that the hard, brittle metal first obtained has been converted into the soft, strong, and durable product described in the opening paragraphs. From this brief description it will be evident that the manufacture of malleable iron is an operation both complicated and expensive, owing to the double process involved. At the same time, however, it should be quite clear that the superior quality of the metal obtained more than repays the difficulties of its manufacture. 557 HOW A ROSEBUD UNCLOSES DID you ever watch a rosebud unclose? If not, you have missed one of nature's wonderful processes. cochet variety just as it begins to unfold. I warn you beforehand Take a bud of the crimson that to watch this transition from bud to rose will require much patience. Nature requires patience first of all from those who would learn her secrets. For three hours you can see no difference in the bud; seemingly it is absolutely idle. You will perhaps perceive, at the end of that time, that the bud is larger, especially in girth, and that the color is several shades darker. These changes have gone on within the bud. The little inner petals have awakened and are sleepily stretching themselves, and by their quickened life are sending through the veins of the delicate outer petals a flood of deeper color. Now, almost imperceptibly at first, the outer leaves begin to unclose. Watch closely. A tremor seems to run through the outermost petal; then suddenly it falls a little from its fellows. A second or two later another quivers and falls away, and then another, until finally the first four courses are leaning back. Now the movement begins again from within. The little petals at the centre begin to push out. The first perfume is exhaled. Those little petals push farther and farther until the petals of the fifth course touch those of the fourth; then the movement ceases. The bud is a full-blown rose. STRAWBERRY PICKING As the sun rises over the dewy, glistening field, the manager, a short businesslike man with a quick eye and a quicker step, comes out of the shed with the bosses. To these bosses he assigns spaces of about twenty rows each. The duty of this functionary is to watch the pickers in his territory, keep them on their own rows, see that they pick the berries properly and do not mash those on the edges of the rows nor leave any which would be too ripe for the next picking, which occurs the second day after. His place is about as agreeable as that of a baseball umpire. When the bosses are allotted their positions, the signal is given and the pickers, one to each row, merrily set to work. The cool dew wets hands and arms and trousers or skirts as, on their knees, the pickers rapidly turn the leaves this way and that, searching for the luscious low-lying fruit. The girls, their hands and arms covered with the legs of old stockings, race and talk with their neigh |