The farther descent of the bucket being thus arrested, the special cable T is now slackened, so that the conical bottom of the bucket drops down, pressing down by its weight the the string of moulds, each thus containing a pig, moves slowly forward, the pigs solidify and cool, the more quickly because in transit they are sprayed with water or even submerged in L Winter Stock Pile .?t' S ..
This alloy, if allowed to solidify completely before chilling, turns into a uniform solid solution, and at still lower temperatures the solid solution breaks up into a pearlite complex.
But in addition to the greater cost of steel founding as compared with rolling there are two facts which limit the use of steel castings: (1) they are not so good as rolled products, because the kneading which the metal undergoes in rolling improves its quality, and closes up its cavities; and (2) it would be extremely difficult and in most cases impracticable to cast the metal directly into any of the forms in which the great bulk of the steel of commerce is needed, such as rails, plates, beams, angles, rods, bars, and wire, because the metal would become so cool as to solidify before running far in such thin sections, and because even the short pieces which could thus be made would pucker or warp on account of their aeolotachic contraction.
In case of direct puddling and the use of larger charges this conservatism has some foundation, because the established custom of allowing the cast iron to solidify gives a better opportunity of examining its fracture, and thus of rejecting unsuitable iron, than is afforded in direct puddling.
Such ferns as Gymnogrammes, which have their surface covered with golden or silver powder, and certain species of scaly-surfaced Cheilanthes and Nothochlaena, as they cannot bear to have their fronds wetted, should never be syringed; but most other ferns may have a moderate sprinkling occasionally (not necessarily daily), and as the season advances, sufficient air and light must be admitted to solidify the tissues.
In a very few places the molten cast iron as it issues from the blast furnace is cast directly in these moulds, but in general it is allowed to solidify in pigs, and then remelted either in cupola furnaces or in air furnaces.
It is deposited from water, which bubbles up from a number of springs in the form of horizontal layers, which at first are thin crusts and can easily be broken, but gradually solidify and harden into blocks with a thickness of 7 to 8 in.
For example, the compound Cu3Sn is not indicated in the freezing-point curve, and indeed a liquid alloy of this percentage does not begin to solidify by the formation of crystals of Cu 3 Sn; the liquid solidifies completely to a uniform solid solution, and only at a lower temperature does this change into crystals of the compound, the transformation being accompanied by a considerable evolution of heat.
Recent investigations point to the conclusion that the immediate cause of the arrest of vitality, in the first place, and of its destruction, in the second, is the coagulation of certain substances in the protoplasm, and that the latter contains various coagulable matters, which solidify at different temperatures.
Both mix with warm water in all proportions, and will solidify in certain conditions.