October i8, 19 17] 



NATURE 



^35 



structure is still a matter of pure conjecture. It is to 

 he hoped that the authors will investigate this aspect 

 of the research, difficult though it will probably prove 

 to be. 



The authors entitled their paper "A Note on the 

 Microstructure of Commercially Pure Iron between 

 \r3 and Ar2." Strictly speaking, this is not the case. 

 Mr. P. Tucker, w^ho took cooling and heating curves 

 for them, found Ac3 at 888° C. and Ar3 at 874° C, 

 and makes the significant statement that it was 

 " practically impossible so far to determine the Ar2 

 point of this material even on the most delicate in- 

 struments." Now the new structural constituent is 

 shown in the photographs at 899° C, while the mate- 

 rial was still in the y range — above Ar3. It does not 

 appear, therefore, that the' upper limit of brittleness 

 coincides with the Ar3 change. Ar2 is normally found 

 at about 765° C. in commercially pure irons. This is 

 about 35° lower than ihe temperature at which the 

 eutectoid structure disa;ppeared. No iron has ever 

 been found to give Ar2 at so high a temperature as 

 800° C, which is actually below that at which the 

 new constituent vanishes. Neither, therefore, does 

 the lower limit of brittleness coincide with the Ar2 

 change, assuming that it does exist, according to the 

 evidence at present available. 



H. C. H. Carpenter. 



RECENT RESEARCHES AT VESUVIUS. 



pROF. ALESSANDRO MALLADRA, the suc- 

 -*■ cessor of Mercalli at the Roj-al Vesuvian observa- 

 tory, has published a number of papers, from 1912 

 onwards, on the volcanic manifestations and progres- 

 sive changes in the great crater formed in 1906. It 

 has been possible in recent years to descend, by hazard- 

 ous paths, to the edge of the central funnel, 250 metres 

 below the crater-edge, and valuable observations have 

 been made on the gases emitted from the fumaroles. 

 Prof. Malladra furnishes a well-illustrated summary of 

 the conditions in 1914 in " Nel cratere del Vesuvio " 

 (Boll, reale Soc. Geografica, 1914, p. 753). The 

 gradual widening of the crater by the falling in of its 

 cliffs is shown in plan in a paper, " Sulle modificazioni 

 del Vesuvio dopo il 1906 " (ibid., p. 1237). The small 

 aperture of 1900 is also here indicated, almost imme- 

 diately over the pit that is now active. The volcano 

 remained quiet, in a solfataric stage, for seven 

 years after the enormous outburst of 1906; but a 

 glowing funnel opened in the floor of the crater of 

 explosion on July :;, 19 13. Prof. Malladra was en- 

 j^aged in a hypsometrical survey on the cone a few- 

 hours after this outbreak (" Sui fenomeni consecutivi 

 air apertura della bocca :; Luglio, 1913," Rend. R. 

 Accad. Set. Fis. e Mat. di Napoli, fasc. 11 and 12, 

 19 14), and has recorded a true incandescence, accom- 

 panied by the emission of fresh scoriae, specimens of 

 which were collected on one of many later visits. The 

 "yellow fumarole" in the crater gave a temperature- 

 reading of 128° C. in 191 1. In September, 1913, this 

 had risen to 330°, and in October to 347°. During 

 the collection of gases from this fumarole for analysis, 

 water condensed, containing hydrochloric acid in the 

 proportion of 9-21 grams per" 100 c.c, and smell- 

 ing strongly of sulphuretted hydrogen. The author 

 points out that, following the arguments of 

 Brun as to the possibility of the permeation 

 of wat^r into a heated mass from without, this water 

 must be truly magmatic. He thus provides further 

 evidence, in addition to that of Day and Shepherd, 

 against Brun's main contention. 



Prof. Malladra illustrates ("I Gas vulcanici e la 

 Vegetazione," Boll. Soc. Sismologica Ital., vol. xviii.) 

 the acid gases of Vesuvius rolling in a dense cloud 

 NO. 2503, VOL. 100] 



down the mountain slope. They deposit on the leaves 

 and branches of the trees a white dust consisting of 

 chlorides and sulphates of iron and the alkalies ; and 

 these anhydrous or slightly hydrated gases are easily 

 recognisable to the experienced eye from the ordinary 

 masses of water vapour. Like the descending clouds 

 that brought death to Saint-Pierre and Morne Rouge, 

 they consist of very finely divided solid matter and 

 gas, and resemble the smoke of a conflagration. The 

 caustic effect produces brown spots and decay in 

 leaves, and experiments are in progress in the planting 

 of bare parts of the Vesuvian slopes with Euonymus 

 and with a bamboo, appropriately known as Arundo 

 Plinii, which flourishes fairly upon Stromboli. Both 

 these, it is hoped, will resist the acid emanations. 



An investigation of the rainfall on Vesuvius, and of 

 the distribution of snow on the variously heated areas 

 near the vent ("La pioggia sul Vesuvio, 1863-1913," 

 ibid., vol. xviii.), contains an interesting passage on 

 the snow-accumulations formed by the freezing of the 

 vapour of the fumaroies. G. A. J. C. 



FUEL RESEARCH.^ 



IN its first report^ the Board stated that it had 

 in view two main lines of research : first, a survey 

 and classification of the coal seams in the various 

 mining districts by means of chemical and physical 

 tests in the laboratory, and, secondly, an investigation 

 of the practical problems which must be solved if any 

 large proportion of the raw coal at present burned in 

 its natural state is to be replaced by the various forms 

 of fuel obtainable from coal by carbonisation and gasi- 

 fication processes. 



When the previous report was written it was be- 

 lieved that the survey and classification of coal seams 

 might be proceeded with in advance of the second line 

 of inquiry ; but further consideration has shown that 

 from the practical point of view the two lines are so 

 thoroughly interdependent that they can be most satis- 

 factorily dealt with side by side. This view will be 

 further developed after the position and prospects with 

 regard to the second line of inquiry have been more 

 fully explained. 



In preparation for the organisation of the first line, 

 however, an experimental study of standard methods 

 for the examination of samples of coal in the labora- 

 tory has been made. Hitherto in the systematic exam- 

 ination of coals in the laboratory there has been no 

 generally accepted low-temperature carbonisation test. 

 In the survey and classification of coals for the pur- 

 poses of the present inquiries a test of this kind is 

 practically indispensable. Certain existing tests are 

 designed to ascertain the suitability of coal for gas- 

 or coke-making, but as both these methods of carbon- 

 isation are carried out at temperatures above 900° C. 

 they give little or no direct information as to the be- 

 haviour of the coal w'hen carbonised at 500° to 600° C. 



.As a result of experimental work carried out for the 

 Board in the fuel laboratory of the Imperial College 

 of Science and Technology, a test has now been elabo- 

 rated which by direct weighing and measurement gives 

 the yields of gas, oil, water, and carbonaceous residue 

 which result from carbonisation at any definite tem- 

 perature. The apparatus is simple and is so arranged 

 that the progress of the distillation can be watched 

 from start to finish. The products can be weighed or 

 measured with reasonable accuracy, and any or all of 

 them can, if desired, be submitted to further examina- 

 tion. 



1 Report (slightly abrideed) of the Fori Researrh Board on it« Scheme 

 of Research and on the Establishment of a Fuel Research Station. (Pub- 

 hshed for the Department of Scientific and Industrial Research by H.M- 

 Stationery Office.) Price 2if. net. 



2 '1 his report was not published. 



