536 



NA TURE 



[September 27, 1900 



result given indicates that when carbon is added by the cement- 

 ation process, the phosphide, when in large quantity, is thrown, 

 not only out of solution, but escapes entirely out of the metal as 

 aliqaid eutectic leaving a constant residuum behind. A method 

 is described by which phosphorus compounds in pig iron can be 

 identified by means of the microscope. This consists in simply 

 heating the polished surfaces to about 300° C. for a few 

 minutes, when each constituent takes a different oxidation tint. 

 The iron acquires a sky-blue colour, the carbide a red-brown 

 and the phosphide compound a pale yellow. The coloured 

 sections are of great beauty. Many results are given showing 

 how the solid phosphide diffuses in solid iron, and showing that 

 under suitable conditions well-formed crystals will grow in solid 

 metal. 



Mr, H. Bauerman's paper on iron and steel at the Universal 

 Exhibition, Paris, 1900, was prepared mainly for the use of the 

 members of the Institute visiting the Exhibition during the meet- 

 ing. It contained a critical description of the more prominent 

 metallurgical exhibits, and forms a valuable record of the con- 

 dition of the metallurgical industry at the close of the century. 



On September 19, the remaining papers on the programme 

 were dealt with. Chief among these was that by Mr. E. F. 

 Lange, on a new method of producing high temperatures. The 

 principle underlying the process, which is the outcome of re- 

 searches made by Dr. H. Goldschmidt of Essen, is not new, as 

 It is based upon the heat energy developed by the chemical 

 action of aluminium upon oxygen, or rather that between 

 aluminium and certain metallic oxides. The practicability of the 

 process was clearly shown by the welding together during the 

 meeting of two short lengths of heavy girder rails. The method 

 not only opens up a new field for aluminium but also promises 

 to be of considerable importance in engineering work. In the 

 discussion Sir William Roberts-Austen pointed out the extreme 

 precision with which the reduction took place, and Sir Lowthian 

 Bell dwelt on the value of the process if it should prove that 

 carbonless iron could be obtained by it for electrical purposes. 



The paper by Mr. A. L. Colby, of Bethlehem, United States, 

 on American standard specifications and methods of testing iron 

 and steel, embodied the results of over a year's work by a com- 

 mittee of American experts, conducted with a view to the adop- 

 tion of international standards. Some of the specifications 

 were criticised by Mr. R. A. Hadfield. The engineer, he 

 thought, was encroaching on the field of the metallurgist. In- 

 teresting contributions to the discussion were made by Mr. C. P. 

 Sandberg and by Dr. Dudley, of Pennsylvania. 



In a paper on the influence of aluminium on the carbon in 

 cast-iron, Mr. G. Melland and Mr. H. W. Waldron gave the 

 results of an elaborate research in which they endeavoured to 

 detertpine the amount of aluminium which is necessary to pro- 

 duce the maximum separation of graphite in a white pig-iron as 

 free as possible from silicon and other impurities, and to ascer- 

 tain, by casting every melting both in sand and in chill moulds, 

 the effect produced by slow and rapid cooling upon the mode of 

 existence of the carbon in the metal with amounts of aluminium 

 varying from 0'02 to 12 per cent. 



In the paper by Mr. Louis Katona, of Resicza, Hungary, the 

 various disadvantages of the rolling-mills now in use were dis- 

 cussed, and suggestions were made for obviating them with a 

 view to increasing the output and lessening the fuel con- 

 sumption. 



In a lengthy paper on the constitution' of slags, which was 

 taken as read, Baron H. von Jtiptner discussed iron slags from 

 a modern point of view, and described the varying reactions 

 which take place between them and iron. The slags considered 

 are divided into three groups — silicate slags, phosphate slags 

 and oxide slags. The results of the investigation tend to show 

 that slags should be regarded as solutions, and not as compli- 

 cated chemical compounds. 



The " phase-rule " of Gibb has served as a guide to the authors 

 of two well-reasoned papers of great scientific interest — one on 

 iron. and steel from the point of view of the phase doctrine, by 

 Prof. Bakhuis-Roozeboom, of Amsterdam, and the other on the 

 present position of the solution theory of carburised iron, by Dr. 

 A. Stansfield. The phase rule says in effect that in a system 

 such as that of the carburised irons, in which two distinct sub- 

 stances (carbon and iron) are involved, but in which certain 

 forms or phases of carbon or iron, or carbon-iron solution, or 

 carbon-iron compound, are present, no more than two of these 

 phases can exist in equilibrium with each other at a particular 

 temperature. In the case of a solution of salt in water, this 



NO. 16 I 3. VOL. 62] 



would mean that there could only be salt and ice and solution 

 together at a particular temperature (the eutectic temperature), 

 and that at any other temperature there could only be ice and 

 solution or salt and solution (.at temperatures above the eutectic), 

 or ice and salt (at temperatures below the eutectic). In the case 

 of a salt solution this is quite evident, but the value of the phase 

 rule is that we can apply it with equal confidence in cases where 

 we do not, to begin with, know the answer to our question. 

 Applying the rule to the case of solid carburised iron at tem- 

 peratures above that of all the known allotropic charges— we 

 have the four possible substances of iron,- graphite, cementite 

 and solid solution of carbon (either graphite or cementite) in 

 pig-iron. The rule states that only two of these can in general 

 exist permanently together. The general conclusions to be 

 drawn from Dr. Stansfield's researches are : — 



(i) That carbon is less soluble in iron when presented in the 

 form of graphite than when presented in the form of cementite. 



(2) That the apparent reversal of this in steel is due partly to 

 the absence of nuclei of graphite on which further deposits might 

 take place ; partly to the length of time required for the separa- 

 tion of the graphite, involving, as it does, the gradual passage of 

 carbon through the iron to reach the nuclei, and partly to the 

 mechanical pressure which must oppose the formation of graphite 

 in solid steel. 



The meeting was brought to a close by a vote of thanks to' the 

 French authorities and societies, whose hospitality had been 

 enjoyed, proposed by the president and seconded by Mr. W. 

 Whitwell, president-elect. A vote of thanks to the president was 

 proposed by Mr. Greiner, of Seraing, Belgium, and seconded 

 by Mr. Nordenfelt. The social functions in connection with the 

 meeting were of a very attractive character. They included an 

 operatic entertainment organised by the Comite des Forges, a 

 reception by the Commissioner-General and Mrs. Jekyll at the 

 British Royal Pavilion, a banquet at the Hotel Continental, a 

 reception by Mr. E. Schneider in the Le Creusot pavilion, a re- 

 ception at the Hotel de Ville by the president of the Municipal 

 Council, and a reception on September 24 by the Minister of 

 Public Works. 



THE BRADFORD MEETING OF THE 

 BRITISH ASSOCIATION. 



SECTION K. 



Opening Address by Prof. S. H. Vines, M.A., D.Sc, 

 F.R.S., President of the Section. 



There has been considerable difference of opinion as to 

 whether the present year marks the close of the nineteenth or 

 the beginning of the twentieth century. But whatever may be 

 the right or the wrong of this vexed question, the fact that the 

 year-date now begins with 19, instead of with 18, suggests the 

 appropriateness of devoting an occasion such as the present to 

 a review of the century which has closed, as some will have it, 

 or, in the opinion of others, is about to close. I therefore pro- 

 pose to address you upon the progress of Botany during the 

 nineteenth century. 



I am fully conscious of the magnitude of the task which I 

 am undertaking, more especially in its relation to the limits of 

 time and space at my disposal. So eventful has the period been 

 that to give in any detail an account of what has been accom- 

 plished during the last hundred years would mean to write the 

 larger half of the entire history of Botany. This being so, it 

 might appear almost hopeless to attempt to deal with so large 

 a subject in a Presidential Address. But I trust that the veiy 

 restrictions under which I labour may prove to be rather ad- 

 vantageous than otherwise, inasmuch as they compel me to 

 confine attention to what is of primary importance, and thus to 

 give special prominence to the main lines along which the 

 development of the science has proceeded. 



We may well begin with what is, after all, the most funda- 

 mental matter, viz. the relative numbers of known species of 

 plants at the beginning and at the end of the century. It might 

 appear that the statistics of plants was a subject susceptible of 

 very simple treatment, but unfortunately this is not the case. It 

 must be remembered that a "species" is not an invariable 



