September 2, 1909] 



NATURE 



287 



Even colloids are being brouglit into line. Stiuklcd as 

 they are with active centres (oxygen or nitrogen atoms), 

 they seem to be able to attract and retain hydrone mole- 

 cules at their surfaces in ways which give thorn their 

 peculiar glue-like attributes : as a consequence living tissue 

 appears to be little short of animated water. 



To the present generation of students, the organo-metallic 

 compounds must have appeared to belong to the past ; the 

 discovery of methides of platinum and gold by Pope will 

 not only serve to re-awaken interest in this group of com- 

 pounds but is of primarv importance as a contribution to 

 our knowledge of the valency of these elements ; the 

 stability of the platinum derivatives is altogether astonish- 

 ing. 



The discovery announced in June last, at the Inter- 

 national Congress of Chemistry, by Mond, of compounds 

 of carbonic oxide with rutherium and uranium is a striking 

 and most welcome extension of his previous labours, which 

 had placed us in possession of carbonyls of nickel, iron and 

 cobalt. The metallic carbonyls possess altogether remark- 

 able properties : at present, these defy explanation ; nickel 

 carbonvl in particular seems to be an exception to all rules. 

 The complex iron carbonyls made known by Dewar and 

 Jones also have most fascinating attributes, the variety of 

 colours they display being specially interesting. The 

 marked individuality of the members of the iron group as 

 exemplified in their carbonyl derivatives is in striking con- 

 trast with the tendency they display to behave as related 

 elements ; the deeper problems of valency are clearly exposed 

 for consideration in such peculiarities. 



The discoveries of the special activity of magnesium as 

 a synthetic agent and of the superior value of nickel as a 

 catalyst in fixing hydrogen are other illustrations of the 

 individuality of metallic elements. We are greatly indebted 

 to the French chemists for the invaluable preparative 

 methods they have based on the use of these two agents. 



Although satisfactory progress has been made in almost 

 every direction, many of the nitrogen compounds are still 

 not properly understood. It is clear that we are as yet in 

 no way seized with understanding of the attributes of this 

 element as we are of those of oxygen and carbon, particu- 

 larly in the case of mixed carbon-nitrogen compounds : 

 we can make nothing of the physical data such substances 

 afford. Nitrogen, in fact, is an extraordinary element, far 

 more remarkable than any other ; its " temper " appears to 

 vary more than that of any other element according to the 

 character of its associates — nothing could be more remark- 

 able, for example, than the change in properties from 

 ammonia, NH,, through hydrazine, NH,.NH,, to azoimide, 

 NjH. No other clement can be so poisonous, so imme- 

 diately fatal to life. We lack a model symbolic of its 

 functions — which means that we are unable to fathom its 

 vagaries and reduce them to simple order. 



Ihe oximes and the diazo-compounds in particular have 

 given rise to much dispute. Stereo-chemical formulae have 

 been assigned to these, but probably they have little relation 

 with the truth ; although they have been of service by 

 supplying symbols which can be offered up at examinations, 

 by confining attention they have served to sterilise inquiry. 

 No better illustration could be given of the truth of the 

 remark made by my friend the Professor that man is an 

 idolater by nature, a fact that chemists should always bear 

 in mind. 



The compounds in question are difficult substances to 

 handle, far too prone to undergo change without invitation 

 — it is to be feared that many of the conclusions which 

 have been arrived at are based on incomplete if not un- 

 satisfactory evidence.' When I think of the state of our 



possesses us : moreover, our attempts to imitate if not to undo her work are 

 never direct but are always made with her aid, with Nature's product — coal : 

 we are no longer content to ride on horseback but must rush through space 

 and instead of watching the birds fly seek to emulate them but always with 

 the aid of fuel won by Nature from the soil and air in days long past. Too 

 much is being done in every direction to waste natural resources, too little 

 to conserve them, too little to employ man in his proper place — as tiller of the 

 soil. Here lies the chemist's opportunity. At no very distant date, perhaps, 

 when petrol is exhausted, toll will be taken from the sun in the form of starch 

 or sugar and this will be converted into alcohol. 



1 .Since this was written, Thiele's discovery of " Azomethane," MeN : NMe, 

 has been announced. This is described as being, in the solid state, a dis- 

 tinctly coloured, ver>- pale yellow substance. "There can be little if any 

 doubt, therefore, that, as Roljertson and I have argued, the colourless so- 

 called syn- and antidiazo-salts cannot possibly be compounds of the — N ; N — 

 or diazene type ; such compounds would all be at least yellow in colour. 



NO. 2079, VOL. 81] 



knowledge, I am reminded of the father of diazo-chemistry,- 

 Peter Griess, and of his marvellous experimental gifts ; 

 there is great need of such a man to re-investigate the 

 whole subject. 



If we inquire as to the general effect of the increase of 

 knowledge of organic compounds, it is clear that the 

 lessons which emerge from all modern inquiries are such as 

 to justify Larmor's remark that our conceptions of structure 

 must be granted more than analogical significance. Every- 

 thing tends to show that function and structure are most 

 closely connected — odour, taste, colour, physiological effect, 

 are specific rather than general properties, each conditioned 

 in its special variety by some special structure; we are 

 approaching very closely to a time when it should be pos- 

 sible to discuss such properties with considerable confidence. 



Still, it must not be forgotten that the problems they 

 offer are all valency problems, and that the nature of 

 valency eludes us entirely at present. 



The greatest advance which chemists may pride them- 

 selves upon having made during the past decade or two 

 remains to be considered. In 1S85, I spoke as follows : — 

 " The attention paid to the study of carbon compounds 

 may be more than justified both by reference to the results 

 obtained and to the nature of the work before us ; the 

 inorganic kingdom refuses any longer to yield up her 

 secrets — new elements — except after severe compulsion ; the 

 organic kingdom, both animal and vegetable, stands ever 

 ready before us. Little wonder, then, if problems directly 

 bearing upon life prove the more attractive to the living. 

 The physiologist complains that probably 95 per cent, of 

 the solid matters of living structures are pure unknowns to 

 us, and that the fundamental chemical changes which 

 occur during life are entirely enshrouded in mystery. It 

 is in order that this may no longer be the case that the 

 study of carbon compounds is being so vigorously prosecuted. 

 Our weapons — the knowledge of synthetical processes and 

 of chemical function— are now rapidly being sharpened, 

 but we are yet far from ready for the attack."^ 



My forecast has been more than justified; indeed, the 

 advance to be recorded is nothing short of marvellous : 

 the great problems of, vital chemistry appear now no 

 longer to be unattainable to our intelligence — their cryptic 

 character seems to have disappeared almost suddenly. 

 Many have contributed in greater or less degree, but none 

 in such measure as Emil Fischer, whose work both in the 

 sugar group and in connection with the albuminoids must 

 for ever rank as monumental. 



It is difficult to appreciate the extent to which the prac- 

 tical genius of this chemist has carried us — difficult alike 

 for those who understand the subject and those who do 

 not ; the significance of his labours is only apparent when 

 the bearing of his results on the interpretation of vital 

 phenomena is fully considered. In 1S85 we were disputing 

 as to the structure of substances such as glucose and: 

 galactose ; now we not only are satisfied that they belong 

 to the group of aldhexoses (aldoses) derived from normal 

 hexane, but, taking into account the monumental dis- 

 coveries of Pasteur, to which precision has been given by 

 van 't Hoff's great generalisation, we are in a position 

 to assign fully resolved structural formulx not only to 

 the natural products but to the nine other isomeric 

 aldhexoses which Fischer has prepared artificially. 



It is a striking fact that only three of the sixteen possible 

 aldhexoses and but a single ketohexose (fructose), of which 

 many are possible, are met with naturally. Nature is 

 clearly most sparing, most economical, in her use of 

 materials. And not only is this true of the hexoses, as 

 very few of the possible lower and higher homologous 

 carbohydrates occur in vegetable or animal materials and' 

 the condensed carbohydrates (cane sugar, starch, &c.) are 

 all formed apparently from the hexoses and pentoses which 

 occur naturally. The albuminoids, the alkaloids, the 

 terpenes are also optically active substances ; in other 

 words, only a limited number of the possible forms are 

 present. There is reason to suppose that the compounds 

 of natural occurrence stand in close genetic connection 

 and belong with few exceptions to the same series of 

 enantiomorphs ; in no other way is it possible to account 

 for the occurrence of one only of the pair of enantio- 

 morphous isomerides and for the relatively small number 



