464 



KNOWLEDGE. 



December, 1913. 



behaviour of ninety different mould-fungi was investigated, 

 and it was found that two forms of Aspergillus and five 

 forms of Penicillium were the chief micro-organisms 

 possessing this property. Among the moulds growing on 

 arsenical paint on the damp walls of a room there was also a 

 variety of Actinomyces, which appeared to be of common 

 occurrence. When grown on culture media this mould 

 formed colonies of a chalk-white appearance, owing to the 

 production of spores. 



ATOMIC WEIGHT OF CHLORINE.— Two critical 

 studies of the published determinations of the atomic weight 

 of chlorine are given in the Chem. Zentralblatt (1913, II, 

 572). In the first of these by Dr. A. Guye, the collated 

 results obtained by the classic method of precipitating the 

 chlorine with silver give the atomic weight as 35-454, this 

 value being dependent upon the atomic weight of silver, which 

 is taken as 107-57 to 107-88. By the more modern method 

 of calculating the atomic weight from the vapour density, 

 chlorine shows the value 35-461, which corresponds to an 

 atomic weight of 107-89 for silver. The calculations of M. E. 

 Wourtzel are in substantial agreement with those of Dr. Guye. 

 Taking the atomic weight of hydrogen as 1-0076 and that of 

 nitrogen as 14-008, the corresponding atomic weight of 

 chlorine was found to be 35-460. 



ENGINEERING AND METALLURGICAL. 



By T. Stenhouse, B.Sc, A.R.S.M., F.I.C. 



CORROSION OF CONDENSER TUBES.— Sir Gerald 

 A. Muntz, Bart., and Professor H. C. H. Carpenter, M.A., 

 Ph.D., the Chairman and Hon. Secretary respectively of the 

 Corrosion Committee of the Institute of Metals, have prepared 

 a statement of a further scheme of work planned by the 

 Committee. A short summary of the experimental work 

 already accomplished was given in the last number of 

 " Knowledge." The new work to be undertaken includes 

 a time-temperature survey of the conditions under which 

 dezincification of condenser tubes can take place, and a more 

 detailed study of the temperatures existing in the experimental 

 condensing plant and other condensers. Special attention 

 will also be directed to the conditions under which electro- 

 chemical protection can be effectively maintained, and in this 

 connection a comparative study of all the principal methods 

 of holding tubes in tube-plates will be carried out. A 

 systematic series of experiments will also be initiated with 

 a set of tubes of a copper-aluminium alloy from which 

 specially interesting results are anticipated. The work will 

 be carried out by Dr. G. D. Bengough, M.A., the Hon. 

 Investigator, the expenses being met by subscriptions to the 

 Corrosion Research Fund of the Institute of Metals. The 

 contributions received to date since the establishment of the 

 fund in January, 1911, amount to nearly £800. 



BRITISH ASSOCIATION— SECTION G.— The report 

 of the Committee to Section G of the British Association, on 

 " Certain of the more complex stress distributions in Engineer- 

 ing Materials," gives a review, with bibliography, of the 

 literature dealing with combined and alternating stresses. In 

 notes contributed by Dr. F. Rogers, the usual causes of the 

 failure of metals under alternating stress are summarised in 

 the three main classes: — (a) Flaws, including pipes, fissures, 

 blow-holes, impurity, and non-metallic enclosures. (6) Faulty 

 original heat -treatment of pure metal. This includes as a 

 special case, strains set up in manufacture, and overwork in 

 the working processes, (c) Under-estimation of stresses to 

 be expected, on the part of the designer. This includes as a 

 special case insufficient allowance for the effect of repetition 

 of a stress which would be harmless if applied once or steadily 

 maintained. 



The Heat Treatment of steel, as affecting endurance, may 

 conveniently be considered in three main classes: — (1) Over- 

 heating, which must be distinguished from "burning," in 

 general, diminishes the endurance under alternating stress. 

 (2) Reheating through the critical range is, in general, 



capable per se of bringing the endurance to a normal high 

 value. (3) The speed of cooling through the critical 

 range has in any event a most profound influence upon the 

 endurance under alternating stress. Generally speaking, it 

 appears that the more rapid this cooling the greater is this 

 endurance. 



GEOGRAPHY. 



By A. Stevens, M.a., B.Sc. 



FIORDS. — The work on the Nature and Origin of Fiords, 

 just published by Mr. Murray for Professor J. W. Gregory, 

 will arouse much interest. Fiords have generally been 

 ascribed to glacial action, but Professor Gregory advances 

 reason for believing that they are the result of earth- 

 movements and faulting, and succeeds at least in discrediting 

 the glacial hypothesis. First of all, it is not true that fiords 

 occur only in glaciated regions, for typical fiords occur in the 

 unglaciated areas of Dalmatia and the North Island of New 

 Zealand. Then it is certain that at least the Scottish fiords 

 are pre-Glacial in age, and the direction of glaciation is often 

 transverse to the line of the fiords, as is shown remarkably in 

 the Shetland Isles, where the ice movement was from east to 

 west, while the inlets are strikingly arranged in a north and 

 south direction. Taking the Scottish lochs for example, they 

 are seen to follow four well-marked sets of lines, trending 

 north-east, north-west, east, and north. Fissure-systems 

 running in these directions are frequent and typical in 

 Scotland. Of these the first is the most striking, and the 

 Caledonian Canal with its line of lochs, and the persistence of 

 the line in the northern shore of the Cromarty Firth and the 

 coast of Sutherland and Caithness, is the most remarkable 

 example. This system is dependent on the well-known 

 Great Glen fault. In the north-west system the branch 

 of Loch Awe, for instance, runs in the Pass of Brander, 

 which is also a fault valley. Then the arrangement 

 of fiords is not that which a glacier system would 

 produce. There is no hint of radiating from central high 

 land that would inevitably be seen in features due to ice, and 

 side fiords join a main fiord of one system from directions 

 that associate them with other systems. It is not only in 

 Scotland that the fiords are associated with the ascertained 

 crack-systems of the country. The phenomenon is seen in 

 Spitzbergen, Dalmatia, and in the other regions described. 

 The distribution of fiords is significant and correlated with 

 the different types of movement characteristic of polar and 

 equatorial regions. They occur mainly on western coasts 

 where the piling up of elevations of the earth's crust is 

 greatest, and just beyond which has taken place extensive 

 foundering ; and this distribution is dependent on the rotation 

 of the earth. The crack-systems are associated with the 

 foundering of the ocean-beds. Two fiord belts exist, the 

 northern nearer the pole than the southern, on account of the 

 tetrahedral plan of the earth.. Along fiord coasts typical 

 fiords are found in the higher latitudes, and pass towards 

 the equator into fiards, which in turn give place to rias. In 

 the fiord regions themselves, in the higher latitudes, are wider 

 rift-inlets and sounds associated with typical networks of true 

 fissure fiords, and nearer the equator the wider rift channels 

 disappear, and only the fiord reticula remain. This succession 

 is wonderfully constant. 



GEOLOGY. 



By G. W. Tyrrell, A.R.C.Sc, F.G.S. 



CALCITE CRYSTALS FROM A WATER TANK.— In 

 view of the frequent occurrence of crystals of carbonates, 

 especially dolomite, in certain argillaceous sediments, the 

 observations of the late R. F. Gwinnell on calcite crystals 

 formed in a water-tank are of interest (Mineralogical 

 Magazine, July, 1913). The crystals were deposited in 

 sand-like heaps in a tank into which water was led, through an 

 old leaden pipe, from a spring in the ferruginous beds at the 

 base of the Marlstone (Middle Lias) to the north of Grantham, 

 Lincolnshire. They were formed during the dry summer of 

 1911, when the flow of water, although not ceasing, was 



