登陆注册
36833600000038

第38章

Those bodies admit of softening which are not (like ice) made up of water, but in which earth predominates. All their moisture must not have left them (as in the case of natron and salt), nor must the relation of dry to moist in them be incongruous (as in the case of pottery). They must be tractile (without admitting water) or malleable (without consisting of water), and the agent in softening them is fire. Such are iron and horn.

Both of bodies that can melt and of bodies that cannot, some do and some do not admit of softening in water. Copper, for instance, which can be melted, cannot be softened in water, whereas wool and earth can be softened in water, for they can be soaked. (It is true that though copper can be melted the agent in its case is not water, but some of the bodies that can be melted by water too such as natron and salt cannot be softened in water: for nothing is said to be so affected unless the water soaks into it and makes it softer.)Some things, on the other hand, such as wool and grain, can be softened by water though they cannot be melted. Any body that is to be softened by water must be of earth and must have its pores larger than the particles of water, and the pores themselves must be able to resist the action of water, whereas bodies that can be 'melted' by water must have pores throughout.

(Why is it that earth is both 'melted' and softened by moisture, while natron is 'melted' but not softened? Because natron is pervaded throughout by pores so that the parts are immediately divided by the water, but earth has also pores which do not connect and is therefore differently affected according as the water enters by one or the other set of pores.)Some bodies can be bent or straightened, like the reed or the withy, some cannot, like pottery and stone. Those bodies are apt to be bent and straightened which can change from being curved to being straight and from being straight to being curved, and bending and straightening consist in the change or motion to the straight or to a curve, for a thing is said to be in process of being bent whether it is being made to assume a convex or a concave shape. So bending is defined as motion to the convex or the concave without a change of length. For if we added 'or to the straight', we should have a thing bent and straight at once, and it is impossible for that which is straight to be bent. And if all bending is a bending back or a bending down, the former being a change to the convex, the latter to the concave, a motion that leads to the straight cannot be called bending, but bending and straightening are two different things. These, then, are the things that can, and those that cannot be bent, and be straightened.

Some things can be both broken and comminuted, others admit only one or the other. Wood, for instance, can be broken but not comminuted, ice and stone can be comminuted but not broken, while pottery may either be comminuted or broken. The distinction is this: breaking is a division and separation into large parts, comminution into parts of any size, but there must be more of them than two. Now those solids that have many pores not communicating with one another are comminuible (for the limit to their subdivision is set by the pores), but those whose pores stretch continuously for a long way are breakable, while those which have pores of both kinds are both comminuible and breakable.

Some things, e.g. copper and wax, are impressible, others, e.g.

pottery and water, are not. The process of being impressed is the sinking of a part of the surface of a thing in response to pressure or a blow, in general to contact. Such bodies are either soft, like wax, where part of the surface is depressed while the rest remains, or hard, like copper. Non-impressible bodies are either hard, like pottery (its surface does not give way and sink in), or liquid, like water (for though water does give way it is not in a part of it, for there is a reciprocal change of place of all its parts). Those impressibles that retain the shape impressed on them and are easily moulded by the hand are called 'plastic'; those that are not easily moulded, such as stone or wood, or are easily moulded but do not retain the shape impressed, like wool or a sponge, are not plastic.

The last group are said to be 'squeezable'. Things are 'squeezable'

when they can contract into themselves under pressure, their surface sinking in without being broken and without the parts interchanging position as happens in the case of water. (We speak of pressure when there is movement and the motor remains in contact with the thing moved, of impact when the movement is due to the local movement of the motor.) Those bodies are subject to squeezing which have empty pores-empty, that is, of the stuff of which the body itself consists-and that can sink upon the void spaces within them, or rather upon their pores. For sometimes the pores upon which a body sinks in are not empty (a wet sponge, for instance, has its pores full). But the pores, if full, must be full of something softer than the body itself which is to contract. Examples of things squeezable are the sponge, wax, flesh. Those things are not squeezable which cannot be made to contract upon their own pores by pressure, either because they have no pores or because their pores are full of something too hard.

Thus iron, stone, water and all liquids are incapable of being squeezed.

Things are tractile when their surface can be made to elongate, for being drawn out is a movement of the surface, remaining unbroken, in the direction of the mover. Some things are tractile, e.g. hair, thongs, sinew, dough, birdlime, and some are not, e.g.

water, stone. Some things are both tractile and squeezable, e.g. wool;in other cases the two qualities do not coincide; phlegm, for instance, is tractile but not squeezable, and a sponge squeezable but not tractile.

同类推荐
热门推荐
  • 天行

    天行

    号称“北辰骑神”的天才玩家以自创的“牧马冲锋流”战术击败了国服第一弓手北冥雪,被誉为天纵战榜第一骑士的他,却受到小人排挤,最终离开了效力已久的银狐俱乐部。是沉沦,还是再次崛起?恰逢其时,月恒集团第四款游戏“天行”正式上线,虚拟世界再起风云!
  • 小小团宠带你飞

    小小团宠带你飞

    一个21世纪的女大学生睡了一觉竟然穿书了,还是一个路人n,行pa!你们睡觉觉,看我飞!!!
  • exo之异能守护

    exo之异能守护

    。。。表示不想多介绍,自己看吧。这篇是给哥哥们的文,里面的女生基本上都是炮灰。
  • 噬梦之战

    噬梦之战

    “如果你打算认识一个最危险的世界,走一条最危险道路、一条救世的道路......这条道路上不管你做了多少善事、不管你救了多少个人,就算你阻止了世界毁灭,也没有一个人会记得你。当你不幸身亡的时候,除了冰冷的棺材和免费的墓地外你什么也得不到。如果你做好决定,随时可以到这个地址来......但,你要想平凡的过完这一生,把它撕碎后从厕所冲下去就好。”
  • 守护甜心之月华倾恋

    守护甜心之月华倾恋

    (几梦文)月华,因落樱而醉;倾恋,因冷月而美……铁杆几梦党雪鸢,窝在守护者半年,终于在胚胎初现时初显锋芒,一举拉近几斗和亚梦的距离…当几斗将亚梦呵护在怀;当几斗诞生了甜心月华,戴雅的真名叫倾恋;当亚梦跳级到初一;当酷似亚梦的夕夏成为新Joker;当复活社袭击唯世意图孤立几斗和亚梦…当一系列的矛盾涌现,几斗和亚梦的爱情将如何发展?亚梦又将如何面对更加残酷的复活社?几梦,空呗,凪璃,唯夕,千雪,他们会幸福吗…《守护甜心之月华倾恋》,值得几梦,空呗,凪璃党一看~
  • 带着神奇宝贝去创造世界

    带着神奇宝贝去创造世界

    运气也算是一种实力的象征。韩羽,你个实力无敌的神,他统治着茫茫宇宙,是世间的主宰而他的弱点就是孤独,为了打败孤独,他来到了神奇宝贝世界,在哪里他得到的真爱,和精灵!
  • 三国随史

    三国随史

    三国,无数男儿梦想的时代,金戈铁马,气吞万里,指点江山。那是一个抛头颅,撒热血的时代;那是一个英雄辈出,你方唱罢我登场的时代。22世纪华夏国的军神,为心爱的女人,创越时空回到三国时代,历史也因此改变了原来的轨道……
  • 丧尸男友——你看起来很好吃

    丧尸男友——你看起来很好吃

    世界duang的一下坏掉了,因为不知名的原因,导致了地球现在变成了丧尸的世界。和电视剧里演的一模一样,丧尸张着血盆大口,随时都有可能出现在你身边咬你一口,两口,三口。而在这个世界里的林艾叶,在逃亡中因为受伤而被同伴抛下。好吧,就在她以为自己没救的时候,迟暮出现了。迟暮是只丧尸,但他会说话,他对艾叶说得第一句话是,你看起来好像很好吃。求人气!!!!!
  • 祝你幸福

    祝你幸福

    祝福,“师奶杀手的助手”,都市典型剩女,三少爷的猪曾经死去的恋人,突然出现。那没有了的孩子呢?那表妹的幸福呢?微笑牙医是最完美的交往对象,以后可以托付的人。但什么才是幸福呢?幸福是非有爱情不可的吗?到底有多爱呢?在现实的面前我们到底可以做何选择?到底什么是幸福呢?多年以后,我们是不是都可以真诚的说出那句:祝你幸福。
  • 预谋成婚:染指娇妻

    预谋成婚:染指娇妻

    他预谋了三年,逼得她退无可退只能嫁给他。可是,可是,为什么,结婚后的他总是喜欢把她欺负得连哭都哭不出来?而可恶的他竟然说那不是欺负。面对她的控诉,他竟然可以无耻到歪曲事实,当真以为她是没有脾气的洋娃娃,既然这样,那她一定要给他好看!