JlNE, IQ04.T 



KX(n\i.]:n(;i' \- sciextific xr.ws. 



log 



difficult to accept, and pouits out that if two globular 

 flasks, such as those in figure 12, one containing a 

 black cloth A and the other a white one B be plunged in 

 vessels of water and exposed to a source of radiant heat 

 such as the sun, then the water in the vessel surrounding 

 A will be hotter than that surrounding 1!, so long as the 

 experiment is continued ; as may be proved by the 

 pressure on the mercury at C, or by observing ther- 

 mometers placed near A and B. 



Fig. II. — Time, eight and a half hours. Distance about 7 cm. 



Now the suggestion is that radium salts may absorb 

 energy in this sort of way from some radiation in the sur- 

 rounding ether, and that we know far too little as yet 

 about radium and about the wave disturbances in the 

 ether to dismiss this explanation of the mystery of radium 

 from consideration before further experiments ha\e been 

 made. 



2. — Is the production of helium from radium " a 

 transmutation"; does it foreshadow similar transmutations 

 among the better known and more plentiful elements, 

 e.g., the transforming of lead into gold or vice versa ? 



It is, I fear, impossible to consider the question in this 

 form seriously till we know much more al)out radium. 



On account of its spectrum, the character of its salts, 

 and their general alliance with the calcium group, 

 radium ranks as an element. Yet if we are exact we 

 cannot truly say radium has never been decomposed, for we 

 explain its most characteristic properties by supposing 

 that every specimen of radium salt is disintegrating spon- 

 taneously and resolving itself gradually into other formsof 

 matter. Hence, it can hardly be regarded as an element 

 in the sense in which oxygen is considered to be 

 an element at this moment. The question before us, 

 therefore, is this — Are the other elements radio-active 

 like radium and its companions ? Do these also, 



though we do not yet recognise the fact, undergo 

 similar transfornialions, only at a far slower rate ? 

 If they do, or if we can prove that some of tiie 

 lighter elements, c.;,'., oxygen, sulphur, or sodium, do so, 

 then the whole ([uestion of the nature of the elements, the 

 very basis of chemistry, must come up for revision. At 

 present the position may be taken, provisionally, to be 

 something of this kind. The elements may, for the 

 moment, be di\ided into two classes. 



{a) Those which have relatively light atoms, and whicli 

 are not, so far as we know at present, subject to 

 disintegration, and are not radio-active, such elements, 

 for example, as helium, oxygen, sodium. 



{!>) Tile radio active forms of matter such as radium, 

 uranium, thorium, which exist in larger particles and 

 exhibit many of the characters of the elements, but 

 which disintegrate, throwing ofiF among their products 

 atoms of elements of the more familiar type. 



Whatever the truth may be, and it seems likely we may 

 long seek the answer to this big question, it is clear tliat 

 the study of radio-active matter must greatly enlarge, 

 iven if it does not re\olutionise, our ideas about the pro- 

 . esses by which tlu: older and more familiar elements have 

 iieen generated. 



The 



Structvire of Crystals. 



By H,\i;oi.i) 1 1 11. ton. 



It is proposed in this paper to give a brief account of the 

 modern geometrical theory of crystal structure. The 

 units of which a homogeneous medium is composed are 

 called •' molecules " ; they are either chemical molecules 



•^ 



6 



V'Z. 1. 



9 



9 



J3 



