212 



KNOWLEDGE ♦ 



[Oct. 5, 1883. 



differently named, was also common among the Indian races 

 Viefore the fifteenth century B.C. The five are curiously 

 correlated -nith the five senses, and they are not looked 

 upon as independent material existences, but as derived 

 from one another. This philosophy was accepted alike by 

 Hindoos and Buddhists. It was largely extended over 

 Asia, and found its way into Europe. It was best known 

 to us in the writings of the Greeks. Among these people, 

 however, the elements were reduced to four — fire, air, earth, 

 and water — though Aristotle endeavoured to restore the 

 " blue ether " to its position as the most subtle and divine 

 of them all. 



For the modern idea we must again travel back to China. 

 In the sixth century b c. the great philosopher Lao-tse and 

 his disciples founded the religion of Taou. They held that 

 the souls of the five elements — water, metal, fire, wood, and 

 earth — arose and became the five planets. At the begin- 

 ning of the seventh century the doctrine of Lao-tse was 

 in great favour at the Chinese court. The disciples of 

 Mahomed carried their arms and his doctrines to the 

 Flowery Land. In the eighth century there were frequent 

 embassies between East and West, wars with Caliphs, and 

 a matrimonial alliance. The teachings of the Taouist 

 alchemists penetrated to Arabia. 



Geber, a Saba?an, started what to the west was a new 

 philosophy about the transmutation of metals. The idea 

 became gradually clearer that all material bodies were 

 made up of certain constituents, which could not be de- 

 composed any further, and which, therefore, should be con- 

 sidered as elementary. The introduction of quantitative 

 methods compelled the overthrow of mediteval chemistry, 

 and led to the placing of the conception of simple and 

 compound bodies upon the foundation of scientific fact. 

 Lavoisier, perhaps, deserves the greatest credit in this 

 matter, while the labours of the other great chemists of 

 the eighteenth and the Ijeginning of the nineteenth cen- 

 turies were in a great measure directed to the analysis of 

 every conceivable material, whether solid, liquid, or gaseous. 

 These have resulted in the table of so-called elements, now 

 nearly seventy in number, to which fresh additions are 

 constantly being made. Of this ever-growing list of ele- 

 ments not one has been resolved into simpler bodies for 

 three quarters of a century ; and we who are removed by 

 two or three generations from the great builders of our 

 science are tempted to look upon these bodies as though 

 they were really simple forms of matter, not only un- 

 resolved, but unresolvable. The notation we employ 

 favours this view and stamps it upon our minds. 



Is it, however, a fact that these reputed elements are 

 really simple bodies ? Or indeed, are they widely different 

 in the nature of their constitution from those bodies which 

 we know to be chemical compounds 1 Thus, to take a par- 

 ticular instance, are fluorine, chlorine, bromine, and iodine 

 essentially distinct in their nature from the compounds 

 halogen, cyanogen, sulphocj-anogen, ferricyanogen, Arc. 1 

 Are the metals lithium, sodium, and potassium essentially 

 distinct from such alkaline bases as ammonium, ethylamine, 

 diethylamine, &c 1 Ko philosophical chemist would pro- 

 bably venture to ask this question categorically with either 

 "Yes" or "No." 



It was at first hoped that the spectroscope might throw 

 much light upon the nature of elements, and might 

 reveal a common constituent in two or more of them. 

 Thus, for instance, it was conceivable that the spectrum 

 line of bromine or iodine vapour might consist of the rays 

 given by chlorine ^)/?/s some others. All expectations of 

 this have hitherto been disappointed ; yet, on the other 

 hand, it must not be supposed that such a result disproves 

 the compound nature of elements, for as investigation 



proceeds it becomes more and more clear that the spectrum 

 of a compound is not made up of the spectra of its com- 

 ponent parts. The general tendency of the arguments is 

 to show that the elementary radicals are essentially dif- 

 ferent from the compound radicals, though their chemical 

 functions are similar. 



There remains still the hypothesis that there is a " pri- 

 mordial element " from which the others are derived by 

 transmutation. With the sages of Asia it was the " blue 

 ether " ; with Thales, water ; with Dr. Prout, hydrogen. 

 The earlier views have passed away, and the claims of 

 hydrogen are being fought out on the battlefield of atomic 

 weights and their rigorous determination. 



There does not appear to be any argument which is fatal 

 to the idea that two or more of our supposed elements may 

 differ from one another rather in form than in substance, 

 or even that the whole 70 are only modifications of a 

 prime element ; but chemical analogies seem wanting. 

 The closest analogy would be if we could prepare two 

 allotropic conditions of some body, such as phosphorus or 

 cyanogen, which should carry their allotropism into all 

 their respective compounds, no compound of the one form 

 being capable of change into a compound of the other. 

 Our present knowledge of allotropism and of variations 

 in atomicity affords little, if any, promise of this. The 

 remarkable relations between the atomic weights of the 

 elements, and many peculiarities of their grouping, force 

 upon us the conviction that they are not separate bodies 

 created without reference to one another, but that they 

 have been fashioned or built up from one another according 

 to some general plan. This plan we may hope gradually 

 to understand better ; but if we are ever to transform one 

 of these supposed elements into another, or to split up one 

 of them into two or three dissimilar forms of matter, it 

 will probably be by the application of some method of 

 analysis hitherto unknown. 



TWO-SPEED TRICYCLES. 



By John Browsing, 



Chairman of the London Tricycle Chii. 



I TRUST I shall be excused for the delay which has 

 occurred in the appearance of this article, but I have 

 withheld the paper until I could give my experience of 

 each machine to which I have to refer. 



The two speed gearings I shall mention in the order in 

 which I have tested them. 



First, then, I must name the Crypto-Dynamic. This 

 elegant contrivance I know less of than any of the rest. 

 I tried it once only on good roads. The gearing for hill 

 riding was equal to 2.3 in., and there was not a steep hill 

 in the neighbourhood. The hill I tried it on I ran up 

 easily, of course. This was more than a year ago, and I 

 have not been able to hear much about the contrivance 

 since ; but it will, I believe, be purchasable by the public 

 next month. It is compact, and easily applied to almost 

 any machine ; but I fear it will work with considerable 

 friction if it has to rotate at any great velocity. Should 

 this prove to be the case, it will not be well adapted for 

 tricycles with small wheels. 



Next I tested Burdess's two-speed Sterling tricycle. 

 This is the simplest contrivance yet introduced. By pedal- 

 ling forward you drive the machine, which has -IG-in 

 wheels, for speed, and it runs as though it were 56 in. By 

 pedalling backward you drive the machine for power, and 

 it runs as though it were 38 in. The motion can be re- 



