THE VISIBLE AND INVISIBLE WORLD 183 



is a fluid or an elastic solid, or a form of motion within, between, or outside ethereal particles. Similarly the exact 

 nature of life and force has yet to be discovered. 



Dr. Thomas Young, in his " Lectures on Natural Philosophy," thus describes the possible relations of the seen 

 and unseen : " We see forms of matter, differmg in subtility and mobihty, under the names of solids, liquids, and 

 gases ; above these are the semi-material existences, which produce the phenomena of electricity and magnetism, 

 and either caloric or a universal ether. Higher still, perhaps, are the causes of gravitation, and the immediate 

 agents in attractions of all kinds, which exhibit some phenomena apparently still more remote from all that is 

 compatible with material bodies. And of these different orders of beings, the more refined and immaterial appear 

 to pervade freely the grosser. It seems therefore natural to beheve that the analogy may be continued still further, 

 until it rises into existences absolutely inmaaterial and spiritual." 



Fortunately for our race it is not necessary to have a profound knowledge of the substances and forces which 

 so materially contribute to our comfort and enjoyment. At the same time it is our bounden duty to examine with 

 all the energy and ability at our disposal matter and force in all their combinations as they occur in the organic 

 and inorganic kingdoms. Electricity especially promises a rich harvest to the original investigator of the future. 

 It is apparently the silver thread which links the seen to the unseen, the Uving to the dead, and which pervades 

 all matter, animate and inanimate. It can be generated by living tissues, and discharged, even as the thunderbolt 

 is discharged, by living animals. It can be produced from inanimate substances by friction and otherwise in such 

 quantity and strength as instantly to kill animals in precisely the same way as the lightning itself does. In 

 electricity we have a form of force found in the inorganic and organic kingdoms which is always available. Its 

 presence in nerves, nerve centres, the spinal cord, the brain and the muscles has much significance when it is re- 

 membered how intimate the connection between the spinal cord, the brain, nerves, and muscles is. The connection 

 points to a substratum of matter and force pervading dead and living inteUigent matter alike. The finer the matter 

 and the more subtle the force, the greater, apparently, is the demand for them in nature, and the wider their 

 apphcabiUty. This is especially true of ether. " Regard the ether as we please, there can be no doubt that its 

 properties are of a much higher order in the arcana of nature than those of tangible matter." 



Sir WiUiam Crookes has played a prominent and distinguished part in discovering and demonstrating the 

 finer properties of matter. 



Nearly a quarter of a century ago, as was explained at a meeting of the Royal Society in March 1902, the 

 results of certain famous experiments in highly rarefied tubes led Sir William to assume the existence of an 

 oltra-gaseous condition of matter ; and in a memorable lecture at the meeting of the British Association in 1879 

 he expressed his opinion that " in studying this fourth state of matter we seem at length to have within our grasp, 

 and obedient to our control, the little individual particles which, with good warrant, are supposed to constitute the 

 physical basis of the universe." Every subsequent experiment having for its object the widening and deepening 

 of our knowledge of the nature of phosphorescence, magnetisation, and the heat of the electric arc has helped to 

 strengthen the belief that this " radiant matter " (to use the original name for the " satellites " of Lord Kelvin, 

 the " corpuscles " of Professor J. J. Thomson, and the " electrons " of Dr. Johnstone Stoney) has some of the pro- 

 perties of matter and some of the properties of energy, and that physicists have at last reached that metaphysical 

 borderland where matter and energy are merged in one another. According to Professor J.J. Thomson's measure- 

 ments the mass of an electron is about the ^^^th part of that of the hydrogen atom, and it leaves the negative 

 pole with a velocity about one-half that of light. Therefore, it is easy to see that, when swarms of electrons rush 

 from the negative pole and meet the knots of atoms of gas in a so-called vacuum, their power of producing hght 

 and heat must be very great. Sir WilUam Crookes regards the electron as " the unit or atom of electricity," and 

 thinks that a positively-charged chemical atom is one with a surplus, and a negatively-charged atom is one having 

 a deficiency, of electrons. Thus he returns to Franklin's one-fluid theory of electricity. 



The electron theory explains an experiment which has long puzzled electricians. It is well known that if a 

 coin be laid on a sensitive plate in absolute darkness and connected with one pole of an induction coil, the 

 developed plate will show an image of the raised parts of the coin. This curious result has generally been explained 

 on the assumption that the electrified stream of air— the so-called " brush discharge "—affects the film just as 

 light does. But Mr. F. Sanford found that even when the coin was embedded in the centre of a block of paraffin 

 three-quarters of an inch thick it could still be photographed by means of the induction coil. In this experiment 

 the coin could not send off electrified air, and the old explanation is out of the question. But since electrons 

 would easily pass from the coin through the paraffin to the sensitive plate, the theory of Sir WiUiam Crookes helps 

 us to a satisfactory solution of the puzzle. Sir William has recently (Chemical News, 1906) added another to his 

 many ingenious and bold speculations. It is well known that when the light of an incandescent body, say of the 

 sun, is passed through a spectroscope, the elements present in the glowing body are shown by the lines on the 



