50 Mr. William Crookes [Feb, 18, 



mixture, our best test for recognising an element, so-called, bas 

 melted away ! Hitberto it bas been considered tbat if tbe atomic 

 weigbt of a metal, determined by different observers, setting out from 

 different compounds, was always found to be constant (witbin, of 

 course, tbe limits of experimental error), then sucb metal must rightly 

 take rank among tbe simple or elementary bodies. We learn from 

 Nordenskiold's gadolinium tbat this is no longer tbe case. Again, we 

 have here wheels witbin wheels. Gadolinium is not an element, but 

 a compound, or rather, perhaps, a mixture of yttrium, erbium, and 

 ytterbium. We have shown tbat yttrium is a complex of five or more 

 new constituents. And who shall venture to gainsay that each of 

 these constituents, if attacked in some different manner, and if tbe 

 results were submitted to a test more delicate and searching than tbe 

 radiant-matter test, might not be still further divisible? Where, 

 then, is tbe actual ultimate element ? As we advance it recedes like 

 the tantalising mirage lakes and groves seen by tbe tired and thirsty 

 traveller in tbe desert. Are we in our quest for truth to be thus 

 deluded and baulked ? The very idea of an element, as something 

 absolutely primary and ultimate, seems to be growing less and less 

 distinct. 



But we have by no means done with the rare earths and their 

 lessons. How is it tbat these bodies are found, as w^e actually find 

 them, associated in certain rare minerals sucb as samarskite and 

 gadolinite, but occurring only in a few localities ? This fact is bard 

 to account for on tbe ordinary theories of the origination of the 

 elements. 



I venture provisionally to conclude that our so-called elements or 

 simple bodies are, in reality, compound molecules. To form a 

 conception of their genesis I must beg you to carry your thoughts 

 back to the time when the visible universe was " without form and 

 void," and to watch the development of matter in tbe states known to 

 us from an antecedent something. What existed anterior to our 

 elements, before matter as we now have it, I propose to name protyle* 



* We require a word, analogous to protoplasm, to express the idea of tbe 

 original primal matter existing before the evolution of the chemical elements. 

 The word I have ventured to use for this purpose is compounded of -n-pS (earlier 

 than) and uA-tj (the stuff of which things are made). The word is scarcely a new 

 coinage, for in the ' Wisdom of Solomon ' (xi., v. 17) we read : — " Thy almighty 

 liaud, that created the world — e| aii6p(pov uX-qs — out of formless stuff," the word 

 here rendered "stuff" being in the original uAtjs, from which I have ventured to 

 coin the word " protyle." Six hundred years ago Roger Bacon wrote in his 

 De Arte ChymicE, " The elements are made out of vXy], and every element is con- 

 verted into the nature of another element." Professor Huxley reminds me that 

 vXt], in the general sense of material substance, was first used by Aristotle, in 

 whose works it is of very frequent occurrence. In fact the fundamental distinc- 

 tion in his Physical Philosophy is between uAtj, or rndter, and (l^os, or form., 

 which last pretty nearly answers to what we should call the sum total of the 

 qualities, powers, and tendencies of a thing — or of forces as the cause of these. In 

 the metaphysics and elsewhere Aristotle distinguishes (1) UpcoTTj v\7], "Materia 



