Radium and Radioactivity

The discovery of the phenomena of radioactivity adds a new group to the great number of invisible radiations now known, and once more we are forced to recognize how limited is our direct perception of the world which surrounds us, and how numerous and varied may be the phenomena which we pass without a suspicion of their existence until the day when a fortunate hazard reveals them.

放射性现象的发现，为人类已知的大量不可见辐射又添了新的一族；我们不得不再一次承认：我们对周围世界的直接感知是多么有限，而我们毫不察觉地从旁经过的现象又可能多么繁多、多么纷杂，直到某一天，一次幸运的偶然把它们揭示出来。

The radiations longest known to us are those capable of acting directly upon our senses; such are the rays of sound and light. But it has also long been recognized that, besides light itself, warm bodies emit rays in every respect analogous to luminous rays, though they do not possess the power of directly impressing our retina. Among such radiations, some, the infra-red, announce themselves to us by producing a measurable rise of temperature in the bodies which receive them, while others, the ultra-violet, act with specially great intensity upon photographic plates. We have here a first example of rays only indirectly accessible to us.

我们认识最久的辐射，是那些能直接作用于感官的辐射，比如声与光。但人们早已认识到，除了光本身以外，温热的物体也会发出射线，它们在各方面都与光线相似，只是不能直接作用于我们的视网膜。在这类辐射中，有一些——红外线——让我们察觉到它，是因为接收它的物体温度会有可测量的升高；另一些——紫外线——则对照相底片有格外强烈的作用。这是我们遇到的第一个例子：有些射线，我们只能间接地触及。

Yet further surprises in this domain of invisible radiations were reserved for us. The researches of two great physicists, Maxwell and Herz, showed that electric and magnetic effects are propagated in the same manner as light, and that there exist “electromagnetic radiations,” similar to luminous radiations, which are to the infra-red rays what these latter are to light. These are the electromagnetic radiations which are used for the transmission of messages in wireless telegraphy. They are present in the space around us whenever an electric phenomenon is produced, especially a lightning discharge. Their presence may be established by the use of special apparatus, and here again the testimony of our senses appears only in an indirect manner. If we consider these radiations in their entirety,—the ultra-violet, the luminous, the infra-red, and the electromagnetic,—we find that the radiations we see constitute but an insignificant fraction of those that exist in space. But it is human nature to believe that the phenomena we know are the only ones that exist, and whenever some chance discovery extends the limits of our knowledge we are filled with amazement. We cannot become accustomed to the idea that we live in a world that is revealed to us only in a restricted portion of its manifestations.

在不可见辐射的领域里，还有更多出人意料之处在等着我们。麦克斯韦和赫兹两位伟大物理学家的研究表明，电与磁的作用以与光相同的方式传播，存在着“电磁辐射”，它们与光辐射相似，它们之于红外线，正如红外线之于光。无线电报传递消息所用的，正是这种电磁辐射。每当有电现象发生，尤其是闪电放电时，它们就出现在我们周围的空间中。要确认它们的存在，须借助特殊的仪器；在这里，我们感官的证词又一次只能间接地出现。如果把这些辐射作为一个整体来看——紫外的、可见的、红外的、电磁的——我们会发现，我们看得见的那部分辐射，在空间中存在的全部辐射里只占微不足道的一小份。然而人的天性总相信，自己知道的现象就是全部存在的现象；每当某个偶然的发现扩展了我们知识的边界，我们便满心惊奇。我们总也习惯不了这样一个想法：我们生活在一个只向我们显露出它一小部分面貌的世界里。

Among recent scientific achievements which have attracted most attention must be placed the discovery of cathode rays, and in even greater measure that of Roentgen rays. These rays are produced in vacuum-tubes when an electric discharge is passed through the rarefied gas. The prevalent opinion among physicists is that cathode rays are formed by extremely small material particles, charged with negative electricity, and thrown off with great velocity from the cathode, or negative electrode, of the tube. When the cathode rays meet the glass wall of the tube they render it vividly fluorescent. These rays can be deflected from their straight path by the action of a magnet. Whenever they encounter a solid obstacle, the emission of Roentgen rays is the result. These latter can traverse the glass and propagate themselves through the outside air. They differ from cathode rays in that they carry no electric charge and are not deflected from their course by the action of a magnet. Every one knows the effect of Roentgen rays upon photographic plates and upon fluorescent screens, the radiographs obtainable from them, and their application in surgery.

近来最受瞩目的科学成就中，必须提到阴极射线的发现，更要提到伦琴射线的发现。当电流通过真空管里稀薄的气体放电时，就会产生这些射线。物理学家普遍认为，阴极射线是由极其微小的物质粒子构成的，它们带负电，以极高的速度从管子的阴极（即负电极）射出。阴极射线打到管壁的玻璃上，会使玻璃发出鲜明的荧光。这些射线可以被磁铁偏转，离开原来的直线路径。它们一旦遇到固体障碍物，便产生伦琴射线。伦琴射线能够穿过玻璃，传播到外面的空气中。它与阴极射线的不同在于：它不带电荷，也不会被磁铁偏转。伦琴射线对照相底片和荧光屏的作用、用它拍摄的透视照片，以及它在外科上的应用，如今人人皆知。

The discovery of Becquerel rays dates from a few years after that of Roentgen rays. At first they were much less noticed. The world, attracted by the sensational discovery of Roentgen rays, was less inclined to astonishment. On all sides a search was instituted by similar processes for new rays, and announcements of phenomena were made that have not always been confirmed. It has been only gradually that the positive existence of a new radiation has been established. The merit of this discovery belongs to M. Becquerel, who succeeded in demonstrating that uranium and its compounds spontaneously emit rays that are able to traverse opaque bodies and to affect photographic plates.

贝克勒尔射线的发现，比伦琴射线晚几年。起初它远没有那么受人注意。世人被伦琴射线那轰动的发现吸引过去，已不那么容易再感到惊讶。各处都有人用类似的方法搜寻新的射线，宣布了一些后来并不总能得到证实的现象。一种新辐射的确实存在，是一点一点才确立起来的。这一发现的功劳属于贝克勒尔先生，他证明了铀及其化合物会自发地放出射线，这些射线能穿透不透明的物体，并使照相底片感光。

It was at the close of the year 1897 that I began to study the compounds of uranium, the properties of which had greatly attracted my interest. Here was a substance emitting spontaneously and continuously radiations similar to Roentgen rays, whereas ordinarily Roentgen rays can be produced only in a vacuum-tube with the expenditure of electrical energy. By what process can uranium furnish the same rays without expenditure of energy and without undergoing apparent modification? Is uranium the only body whose compounds emit similar rays? Such were the questions I asked myself, and it was while seeking to answer them that I entered into the researches which have led to the discovery of radium.

正是在1897年年末，我开始研究铀的化合物，它们的性质深深吸引了我。这里有一种物质，自发地、持续地放出与伦琴射线相似的辐射，而平常的伦琴射线只能在真空管里、靠消耗电能才能产生。铀是通过什么过程，既不消耗能量、又看不出自身有任何变化，就提供出同样的射线？只有铀的化合物会放出这样的射线吗？这就是我向自己提出的问题；正是在设法回答它们的过程中，我走进了最终导致镭的发现的那些研究。

First of all, I studied the radiation of the compounds of uranium. Instead of making these bodies act upon photographic plates, I preferred to determine the intensity of their radiation by measuring the conductivity of the air exposed to the action of the rays. To make this measurement, one can determine the speed with which the rays discharge an electroscope, and thus obtain data for a comparison. I found in this way that the radiation of uranium is very constant, varying neither with the temperature nor with the illumination. I likewise observed that all the compounds of uranium are active, and that they are more active the greater the proportion of this metal which they contain. Thus I reached the conviction that the emission of rays by the compounds of uranium is a property of the metal itself—that it is an atomic property of the element uranium independent of its chemical or physical state.

我首先研究了铀化合物的辐射。我没有让这些物质去作用于照相底片，而是宁愿通过测量受射线作用的空气的导电性，来确定它们辐射的强度。做这种测量，可以测定射线使验电器放电的速度，由此得到可供比较的数据。我用这种方法发现，铀的辐射非常稳定，既不随温度变化，也不随光照变化。我还观察到，铀的所有化合物都有放射性，而且其中铀的比例越大，放射性越强。于是我确信，铀化合物放出射线，是铀这种金属本身的性质——是铀元素的一种原子性质，与它的化学状态或物理状态无关。

I then began to investigate the different known chemical elements, to determine whether there exist others, besides uranium, that are endowed with atomic radioactivity—that is to say, all of the compounds of which emit Becquerel rays. It was easy for me to procure samples of all the ordinary substances—the common metals and metalloids, oxids and salts. But as I desired to make a very thorough investigation, I had recourse to different chemists, who put at my disposal specimens—in some cases the only ones in existence—containing very rare elements. I thus was enabled to pass in review all the chemical elements and to examine them in the state of one or more of their compounds. I found but one element undoubtedly possessing atomic radioactivity in measurable degree. This element is thorium. All the compounds of thorium are radioactive, and with about the same intensity as the similar compounds of uranium. As to the other substances, they showed no appreciable radioactivity under the conditions of the test.

接着我开始考察各种已知的化学元素，看看除了铀以外，是否还有别的元素具有原子放射性——也就是说，它的所有化合物都会放出贝克勒尔射线。要弄到所有普通物质的样品并不难：常见的金属和准金属、氧化物和盐类。但由于我想做一次非常彻底的考察，我便求助于几位化学家，他们把一些含有极稀有元素的标本交给我使用——其中有些是世上仅存的标本。这样我得以把所有化学元素逐一检视，以它们的一种或几种化合物的形态来检验。我只找到一种元素确实具有可测量的原子放射性，这就是钍。钍的所有化合物都有放射性，强度与铀的相应化合物大致相同。至于其他物质，在检验的条件下都没有显示出可以察觉的放射性。

I likewise examined certain minerals. I found, as I expected, that the minerals of uranium and thorium are radioactive; but to my great astonishment I discovered that some are much more active than the oxids of uranium and of thorium which they contain. Thus a specimen of pitch-blende (oxid of uranium ore) was found to be four times more active than oxid of uranium itself. This observation astonished me greatly. What explanation could there be for it? How could an ore, containing many substances which I had proved inactive, be more active than the active substances of which it was formed? The answer came to me immediately: The ore must contain a substance more radioactive than uranium and thorium, and this substance must necessarily be a chemical element as yet unknown; moreover, it can exist in the pitch-blende only in small quantities, else it would not have escaped the many analyses of this ore; but, on the other hand, it must possess intense radioactivity, since, although present in small amount, it produces such remarkable effects. I tried to verify my hypothesis by treating pitch-blende by the ordinary processes of chemical analysis, thinking it probable that the new substance would be concentrated in passing through certain stages of the process. I performed several experiments of this nature, and found that the ore could in fact be separated into portions some of which were much more radioactive than others.

我同样检验了一些矿物。正如我所预料的，铀矿物和钍矿物都有放射性；但令我大为惊讶的是，我发现其中有些矿物的放射性，比它们所含的铀和钍的氧化物强得多。比如一块沥青铀矿（一种铀的氧化物矿石）的放射性，竟是氧化铀本身的四倍。这个观察让我非常吃惊。这该怎样解释？一块矿石，所含的许多物质我已证明并无放射性，它怎么会比组成它的那些有放射性的物质更活跃？答案立刻就来到我心里：这矿石中一定含有一种比铀和钍放射性更强的物质，而这种物质必然是一种尚未为人所知的化学元素；而且，它在沥青铀矿中只能以很少的量存在，否则就逃不过对这种矿石的多次分析；但另一方面，它必定具有强烈的放射性，因为它虽然含量很少，却产生了如此显著的效果。我试着用普通的化学分析方法处理沥青铀矿，来验证我的假设，我想，这种新物质大概会在处理过程的某些步骤中富集起来。我做了几次这样的实验，发现矿石确实可以分离成若干部分，其中一些部分的放射性比另一些强得多。

To try to isolate the supposed new element was a great temptation. I did not know whether this undertaking would be difficult. Of the new element I knew nothing, except that it was radioactive. What were its chemical properties? In what quantity did it appear in pitch-blende? I began the analysis of pitch-blende by separating it into its constituent elements, which are very numerous. This task I undertook in conjunction with M. Curie. We expected that perhaps a few weeks would suffice to solve the problem. We did not suspect that we had begun a work which was to occupy years and which was brought to a successful issue only after considerable expenditure.

设法把这个假想中的新元素分离出来，是一个很大的诱惑。我不知道这项工作会不会很难。关于这种新元素，我一无所知，只知道它有放射性。它的化学性质是什么？它在沥青铀矿里含量有多少？我开始分析沥青铀矿，把它分离成组成它的各种元素，这些元素为数甚多。这项工作我是与居里先生一起承担的。我们原以为也许几个星期就足以解决问题。我们没有料到，我们开始的是一项要占去许多年的工作，而且是在花费了相当大的代价之后才得以成功。

We readily proved that pitch-blende contains very radioactive substances, and that there were at least three. That which accompanies the bismuth extracted from pitch-blende we named Polonium; that which accompanies barium from the same source we named Radium; finally, M. Debierne gave the name of Actinium to a substance which is found in the rare earths obtained from the same ore.

我们很快就证明了，沥青铀矿含有放射性很强的物质，而且至少有三种。随着从沥青铀矿中提取出的铋一起出现的那一种，我们命名为钋；随着同一来源的钡一起出现的那一种，我们命名为镭；最后，德比埃尔内先生把存在于同一矿石所得稀土中的一种物质命名为锕。

Radium was to us from the beginning of our work a source of much satisfaction. Demarçay, who examined the spectrum of our radioactive barium, found in it new rays and confirmed us in our belief that we had indeed discovered a new element.

镭从我们工作的一开始，就带给我们很大的满足。德马尔赛检查了我们那种有放射性的钡的光谱，在其中发现了新的谱线，这使我们确信，我们的确发现了一种新元素。

The question now was to separate the polonium from the bismuth, the radium from the barium. This is the task that has occupied us for years, and as yet we have succeeded only in the case of radium. The research has been a most difficult one. We found that by crystallizing out the chlorid of radioactive barium from a solution we obtained crystals that were more radioactive, and consequently richer in radium, than the chlorid that remained dissolved. It was only necessary to make repeated crystallizations to obtain finally a pure chlorid of radium.

现在的问题，是把钋从铋中分离出来，把镭从钡中分离出来。这就是多年来占据着我们的工作，而到目前为止，我们只在镭这一种上取得了成功。这项研究极其艰难。我们发现，从溶液中让有放射性的氯化钡结晶出来时，得到的晶体比留在溶液中的氯化物放射性更强，因而含镭更多。只需反复结晶，最终就能得到纯的氯化镭。

But although we treated as much as fifty kilograms of primary substance, and crystallized the chlorid of radiferous barium thus obtained until the activity was concentrated in a few minute crystals, these crystals still contained chiefly chlorid of barium; as yet radium was present only in traces, and we saw that we could not finish our experiments with the means at hand in our laboratory. At the same time the desire to succeed grew stronger; for it became evident that radium must possess most intense radioactivity, and that the isolation of this body was therefore an object of the highest interest.

可是，尽管我们处理了多达五十公斤的原料，把由此得到的含镭氯化钡反复结晶，直到放射性集中在几颗微小的晶体里，这些晶体的主要成分仍然是氯化钡；镭只以痕量存在。我们明白，凭实验室里现有的条件，我们无法完成这些实验。与此同时，想要成功的愿望越来越强烈；因为事情已经很清楚，镭一定具有极强的放射性，因而把它分离出来，是一件极有意义的事。

Fortunately for us, the curious properties of these radium-bearing compounds had already attracted general attention, and we were assisted in our search.

幸运的是，这些含镭化合物的奇特性质已经引起了普遍的关注，我们在探索中得到了帮助。

A chemical factory in Paris consented to undertake the extraction of radium on a large scale. We also received certain pecuniary assistance, which allowed us to treat a large quantity of ore. The most important of these grants was one of twenty thousand francs, for which we are indebted to the Institute of France.

巴黎的一家化工厂同意承担大规模提取镭的工作。我们还得到了一些经费资助，使我们能够处理大量的矿石。其中最重要的一笔是两万法郎，我们为此感谢法兰西学会。

We were thus enabled to treat successively about seven tons of a primary substance which was the residue of pitch-blende after the extraction of uranium. To-day we know that a ton of this residue contains from two to three decigrams (from four to seven ten-thousandths of a pound) of radium. During this treatment, and as soon as I had in my possession a decigram of chlorid of radium recognized as pure by the spectroscope, I determined the atomic weight of this new element, finding it to be 225, while that of barium is 137.

这样，我们得以先后处理了约七吨原料，那是沥青铀矿提取铀之后的残渣。今天我们知道，一吨这样的残渣含镭二到三分克（约合万分之四到万分之七磅）。在这一处理过程中，我一拿到经光谱仪认定为纯净的一分克氯化镭，就测定了这种新元素的原子量，得到225，而钡的原子量是137。

The properties of radium are extremely curious. This body emits with great intensity all of the different rays that are produced in a vacuum-tube. The radiation, measured by means of an electroscope, is at least a million times more powerful than that from an equal quantity of uranium. A charged electroscope placed at a distance of several meters can be discharged by a few centigrams of a radium salt. One can also discharge an electroscope through a screen of glass or lead five or six centimeters thick. Photographic plates placed in the vicinity of radium are almost instantly affected if no screen intercepts the rays; with screens, the action is slower, but it still takes place through very thick ones if the exposure is sufficiently long. Radium can therefore be used in the production of radiographs.

镭的性质极其奇特。这种物质以很大的强度放出真空管中所产生的各种射线。用验电器测量，它的辐射至少比同等数量的铀强一百万倍。几厘克镭盐，就能使放在几米之外的带电验电器放电。隔着五六厘米厚的玻璃或铅板，也能使验电器放电。放在镭附近的照相底片，如果没有屏障挡住射线，几乎立刻就会感光；有屏障时，作用慢一些，但只要曝光时间足够长，即使隔着很厚的屏障也仍然会发生。因此镭可以用来拍摄透视照片。

The compounds of radium are spontaneously luminous. The chlorid and bromide, freshly prepared and free from water, emit a light which resembles that of the glow-worm. This light diminishes rapidly in moist air; if the salt is in a sealed tube, it diminishes slowly by reason of the transformation of the white salt, which becomes colored, but the light never completely disappears. By redissolving the salt and drying it anew, its original luminosity is restored.

镭的化合物会自己发光。刚制备出来、不含水的氯化镭和溴化镭，发出的光就像萤火虫的光。这光在潮湿的空气中会迅速减弱；如果盐封在玻璃管里，光会慢慢减弱，因为白色的盐会逐渐变色，但光永远不会完全消失。把盐重新溶解、再次烘干，它原来的光亮就又恢复了。

A glass vessel containing radium spontaneously charges itself with electricity. If the glass has a weak spot,—for example, if it is scratched by a file,—an electric spark is produced at that point, the vessel crumbles like a Leiden jar when overcharged, and the electric shock of the rupture is felt by the fingers holding the glass.

盛着镭的玻璃容器会自动带电。如果玻璃上有一处薄弱点——比如被锉刀划过——那一点就会迸出电火花，容器会像充电过量的莱顿瓶一样碎裂，拿着玻璃的手指会感到破裂时的电击。

Radium possesses the remarkable property of liberating heat spontaneously and continuously. A solid salt of radium develops a quantity of heat such that for each gram of radium contained in the salt there is an emission of one hundred calories per hour. Expressed differently, radium can melt in an hour its weight in ice. When we reflect that radium acts in this manner continuously, we are amazed at the amount of heat produced, for it can be explained by no known chemical reaction. The radium remains apparently unchanged. If, then, we assume that it undergoes a transformation, we must therefore conclude that the change is extremely slow: in an hour it is impossible to detect a change by any known methods.

镭有一种了不起的性质：它自发地、持续地放出热。一块固态镭盐所放出的热量，按盐中所含的每一克镭计算，每小时有一百卡路里。换一种说法：镭在一小时之内，能融化与它等重的冰。当我们想到镭是这样持续不断地作用着，就会对它产生的热量感到惊讶，因为任何已知的化学反应都无法解释它。镭看上去毫无变化。那么，如果我们假定它在经历某种转变，就必须断定这转变极其缓慢：在一小时之内，用任何已知方法都检测不出变化。

As a result of its emission of heat, radium always possesses a higher temperature than its surroundings. This fact may be established by means of a thermometer, if care is taken to prevent the radium from losing heat.

由于放热，镭的温度总是比周围环境高。只要注意不让镭散失热量，用温度计就可以确认这一点。

Radium has the power of communicating its radioactivity to surrounding bodies. This is a property possessed by solutions of radium salts even more than by the solid salts. When a solution of a radium salt is placed in a closed vessel, the radioactivity in part leaves the solution and distributes itself through the vessel, the walls of which become radioactive and luminous. The radiation is therefore in part exteriorized. We may assume, with Mr. Rutherford, that radium emits a radioactive gas and that this spreads through the surrounding air and over the surface of neighboring objects. This gas has received the name emanation. It differs from an ordinary gas in the fact that it gradually disappears.

镭能把它的放射性传给周围的物体。镭盐的溶液比固态的盐更具有这种性质。把镭盐溶液放在密闭的容器里，放射性会有一部分离开溶液，散布到整个容器中，容器的内壁变得有放射性，而且发光。可见辐射有一部分“外化”了。我们可以同卢瑟福先生一样假定，镭会放出一种有放射性的气体，这种气体扩散到周围的空气中，附着在邻近物体的表面上。这种气体被称为“射气”。它与普通气体不同之处在于，它会逐渐消失。

Certain bodies—bismuth, for instance—may also be rendered active by keeping them in solution with the salts of radium. These bodies then become atomically active and keep this radioactivity even after chemical transformations. Little by little, however, they lose it, while the activity of radium persists.

某些物质——比如铋——与镭盐一同保持在溶液中，也可以变得有放射性。这些物质于是获得原子的放射性，即使经过化学变化也仍保持着。不过它们会一点一点失去放射性，而镭的放射性却持续不变。

The nature of radium radiations is very complex. They may be divided into three distinct groups, according to their properties.

镭的辐射性质非常复杂。按照它们的性质，可以分为三个不同的组。

One group is composed of radiations absolutely analogous to cathode rays, composed of material particles called electrons, much smaller than atoms, negatively charged, and projected from the radium with great velocity—a velocity which for some of these rays is very little inferior to that of light.

第一组辐射与阴极射线完全相似，由称为电子的物质粒子组成，电子比原子小得多，带负电，以很高的速度从镭中射出——其中一些射线的速度只比光速稍逊。

The second group is composed of radiations which are believed to be formed by material particles the mass of which is comparable to that of atoms, charged with positive electricity, and set in motion by radium with a great velocity, but one that is inferior to that of the electrons. Being larger than electrons and possessing at the same time a smaller velocity, these particles have more difficulty in traversing obstacles and form rays that are less penetrating.

第二组辐射，人们认为是由质量与原子相当、带正电的物质粒子组成的，它们被镭以很高的速度推动，但速度不及电子。这些粒子比电子大，同时速度又较小，因而穿过障碍物更为困难，形成的射线穿透力较弱。

Finally, the radiations of the third group are analogous to Roentgen rays and do not behave like projectiles.

最后，第三组辐射与伦琴射线相似，其行为并不像抛射体。

The radiations of the first group are easily deflected by a magnet; those of the second group, less easily and in the opposite direction; those of the third group are not deflected. From its power of emitting these three kinds of rays, radium may be likened to a complete little Crookes tube acting spontaneously.

第一组辐射很容易被磁铁偏转；第二组较难偏转，且方向相反；第三组则完全不偏转。由于能放出这三种射线，镭可以比作一支完整的、自动工作的小克鲁克斯管。

Radium is a body which gives out energy continuously and spontaneously. This liberation of energy is manifested in the different effects of its radiation and emanation, and especially in the development of heat. Now, according to the most fundamental principles of modern science, the universe contains a certain definite provision of energy, which can appear under various forms, but cannot be increased.

镭是一种持续地、自发地放出能量的物质。这种能量的释放，表现在它的辐射和射气的种种效应中，尤其表现在放热上。而按照现代科学最根本的原理，宇宙中所含的能量是一定的，它可以以各种形式出现，却不能增加。

Without renouncing this conception, we cannot believe that radium creates the energy which it emits; but it can either absorb energy continuously from without, or possess in itself a reserve of energy sufficient to act during a period of years without visible modification. The first theory we may develop by supposing that space is traversed by radiations that are as yet unknown to us, and that radium is able to absorb these radiations and transform their energy into the energy of radioactivity. Thus in a vacuum-tube the electric energy is utilized to produce cathode rays, and the energy of the latter is partly transformed, by the bodies which absorb them, into the energy of Roentgen rays. It is true that we have no proof of the existence of radiations which produce radioactivity; but, as indicated at the beginning of this article, there is nothing improbable in supposing that such radiations exist about us without our suspecting it.

如果不放弃这一观念，我们就不能相信镭会创造它所放出的能量；它要么是不断从外界吸收能量，要么自身含有一份储备，足以在若干年里起作用而看不出变化。第一种理论可以这样展开：假定空间中有我们尚未知晓的辐射穿行，镭能够吸收这些辐射，并把它们的能量转化为放射性的能量。就像在真空管里，电能被用来产生阴极射线，而阴极射线的能量又被吸收它的物体部分地转化为伦琴射线的能量。诚然，我们没有证据证明存在着产生放射性的辐射；但正如本文开头所说，假定这样的辐射存在于我们周围而我们毫无察觉，并没有什么不可能。

If we assume that radium contains a supply of energy which it gives out little by little, we are led to believe that this body does not remain unchanged, as it appears to, but that it undergoes an extremely slow change. Several reasons speak in favor of this view. First, the emission of heat, which makes it seem probable that a chemical reaction is taking place in the radium. But this can be no ordinary chemical reaction, affecting the combination of atoms in the molecule. No chemical reaction can explain the emission of heat due to radium. Furthermore, radioactivity is a property of the atom of radium; if, then, it is due to a transformation, this transformation must take place in the atom itself. Consequently, from this point of view, the atom of radium would be in a process of evolution, and we should be forced to abandon the theory of the invariability of atoms, which is at the foundation of modern chemistry.

如果我们假定镭含有一份能量储备，并一点一点把它放出来，我们就会相信，这种物质并不像看上去那样始终不变，而是在经历一种极其缓慢的变化。有好几条理由支持这种看法。首先是放热，它让人觉得镭里面很可能正在进行某种化学反应。但这不可能是普通的化学反应，即影响分子中原子之结合的那种反应。没有任何化学反应能解释镭放出的热。其次，放射性是镭原子的性质；那么，如果它源于某种转变，这种转变就必定发生在原子本身之中。因此，从这个观点看，镭原子正处于演变之中，而我们将不得不放弃原子不变的理论——这个理论是现代化学的基础。

Moreover, we have seen that radium acts as though it shot out into space a shower of projectiles, some of which have the dimensions of atoms, while others can only be very small fractions of atoms. If this image corresponds to a reality, it follows necessarily that the atom of radium breaks up into subatoms of different sizes, unless these projectiles come from the atoms of the surrounding gas, disintegrated by the action of radium; but this view would likewise lead us to believe that the stability of atoms is not absolute.

此外，我们已经看到，镭的作用就好像它向空间射出一阵抛射体的雨，其中有些具有原子的大小，另一些则只能是原子的极小部分。如果这个图景符合实际，那就必然推出：镭原子会碎裂成大小不同的“亚原子”；除非这些抛射体来自周围气体的原子，是被镭的作用击碎的——但这种看法同样会让我们相信，原子的稳定并不是绝对的。

Radium emits continuously a radioactive emanation which, from many points of view, possesses the properties of a gas. Mr. Rutherford considers the emanation as one of the results of the disintegration of the atom of radium, and believes it to be an unstable gas which is itself slowly decomposed.

镭持续放出一种有放射性的射气，从许多方面看，它具有气体的性质。卢瑟福先生认为，射气是镭原子蜕变的产物之一，并相信它是一种不稳定的气体，自身也在缓慢地分解。

Professor Ramsay has announced that radium emits helium gas continuously. If this very important fact is confirmed, it will show that a transformation is occurring either in the atom of radium or in the neighboring atoms, and a proof will exist that the transmutation of the elements is possible.

拉姆齐教授宣布，镭会持续放出氦气。如果这个非常重要的事实得到证实，它将表明，在镭原子中或在其邻近的原子中，正在发生某种转变；那就有了证据，证明元素的嬗变是可能的。

When a body that has remained in solution with radium becomes radioactive, the chemical properties of this body are modified, and here again it seems as though we have to deal with a modification of the atom. It would be very interesting to see whether, by thus giving radioactivity to bodies, we can succeed in causing an appreciable change in their atoms. We should thus have a means of producing certain transformations of elements at will.

一种物质与镭一同保持在溶液中而变得有放射性时，它的化学性质会发生改变；在这里，我们似乎又一次面对原子的改变。如果能看看，通过这样赋予物体放射性，我们能否使它们的原子发生可觉察的变化，那将非常有意思。那样我们就有了一种随意使某些元素发生转变的方法。

It is seen that the study of the properties of radium is of great interest. This is true also of the other strongly radioactive substances, polonium and actinium, which are less known because their preparation is still more difficult. All are found in the ores of uranium and thorium, and this fact is certainly not the result of chance, but must have some connection with the manner of formation of these elements. Polonium, when it has just been extracted from pitch-blende, is as active as radium, but its radioactivity slowly disappears; actinium has a persistent activity. These two bodies differ from radium in many ways; their study should therefore be fertile in new results. Actinium lends itself readily to the study of the emanation and of the radioactivity produced in inactive bodies, since it gives out emanation in great quantity. It would also be interesting, from the chemical point of view, to prove that polonium and actinium contain new elements. Finally, one might seek out still other strongly radioactive substances and study them.

由此可见，研究镭的性质是极有意义的。另外两种强放射性物质——钋和锕——也是如此，只是它们的制备更加困难，所以人们对它们了解得更少。它们都存在于铀矿和钍矿之中，这一事实肯定不是偶然的结果，而必定与这些元素的形成方式有某种联系。钋刚从沥青铀矿中提取出来时，与镭一样活跃，但它的放射性会慢慢消失；锕的放射性则持久不衰。这两种物质在许多方面与镭不同；因此研究它们，应当会结出新的成果。锕放出大量射气，很适合用来研究射气，以及不具放射性的物体中被诱发出来的放射性。从化学角度看，证明钋和锕含有新元素，也会很有意思。最后，人们还可以去寻找另一些强放射性物质，并加以研究。