August 14, 19 19] 



NATURE 



473 



liar duplicate male organ not connected with the vas 

 deferens. 



An article on "The Passing of the American Potash 

 Famine," contributed by Prof. P. G. H. Boswell to the 

 Journal of the Society of Chemical Industry (June i6, 

 19 19), states that large quantities of potash will prob- 

 ably be delivered from Germany both to the British 

 Isles and to America. This would seem to suggest 

 that the new potash-obtaining methods introduced 

 during the war are not producing sufficient supplies. 

 In America the total production of potash for 19 17 

 was 50,000 tons, against 230,000 tons imported before 

 the war. Just before the National Exposition of 

 Chemical Industries, held in New York in September, 

 1918, Russian potash was being used to some extent 

 bv the chemical industry, and in large quantities by 

 the glass industry. This potash was obtained from 

 sunflower plants, which were the chief source of fats 

 for the South Russian peasantry. At first it realised 

 as much as 90 cents per lb., but now- it is sold with 

 difficulty at 15 cents. Only a small quantity of this 

 supply was permitted to be exported to Britain, until 

 the restrictions were removed shortly before the armis- 

 tice, when, too, our own supplies were better because 

 of the new recovery process from blast-furnace flues. 

 The greater part of the potash imported in the United 

 States was used for fertilising purposes, and this is 

 thought to have been the result of German propa- 

 ganda work. Obviously the poor, sandy soils of 

 northern Germany and our own much cultivated, and 

 consequently exhausted, soils need potash far more 

 than do the practically virgin soils of America. It is 

 therefore probable that Arnerica will in future use far 

 less potash for fertilising purposes, and, in con- 

 sequence, the world's demand for potash will be much 

 more easily satisfied. 



The microscopic structure of coal has been a matter 

 of scientific interest for the best part of a century," 

 but it was in the year 1854 that the study was started 

 with fresh vigour bv Prof. John Quekett. Again 

 in 1870 the subject was revived by Prof. Huxlev in 

 his article on "The Formation of Coal," and since 

 then it has been approached from time to time, almost 

 always with regard to its vegetable contents, and 

 some papers by J. Lomas and others are still fresh 

 in our minds. A paper recently published by Dr. 

 Marie C. Stones on "The Ingredients of Bituminous 

 Coal " (Proc* Roy. Soc, B, vol. xc, p. 470, 1919) 

 led one to expect some further light upon the botanical 

 side of the question, but this paper attacks the 

 problem from 'an entirely different point of view. 

 "Coal is a rock." the author says, and may be studied 

 in the same way that petrologists work at other rocks. 

 The general structure of coal as seen in sections is 

 described, and the three layers hitherto generally 

 recognised are pointed out ; but the bright layer is 

 now divided so that there are four kinds of substance, 

 for which names are proposed. Some account is also 

 given of "The Behaviour of the Four Ingredients 

 with Certain Chemicals." 



.Mr. J. Morrison puts forward a new view in a 

 paper on "The Shap Minor Intrusions " (Quart. Journ. 

 Geol. Soc. London, vol. Ixxiv., p. 127, rqig) to 

 account for the presence of corroded crystals of ortho- 

 clase and quartz in a magma of basic character. He 

 suggests that differentiation into a granitic type above 

 and a more basic type below occurred in a large body 

 of molten rock, and that the crystals, as they developed 

 in the unper levels, sank through the mass until thev 

 l>ecanie incornonted in the bnsic portion, from which 



NO. 2598, VOL. 103] 



they could not have separated by ordinary processes 

 of crystallisation during cooling. 



Messrs. E. T. Wherry and E. Q. Adams ("The 

 Classification of Mimetic Crystals," Journ. Washington 

 Acad. Sci., vol. ix., p. 153, 1919) endeavour to get rid 

 of the indefinite prehx "pseudo" in mineralogy, when 

 a mineral crystallises in a form closely resembling 

 that of a system other than its own. They describe 

 quartz, for example, not as pseudohexagonal, but as 

 cryptotrigonal and phenohexagonal, and other terms 

 are introduced for cases where crystals compounded 

 by twinning produce forms simulating a foreign degree 

 of symmetry. 



The Annales of the National Observatory of 

 Athens (vol. vii.. 1916) contains several papers 

 by Prof. D. Eginitis and Messrs. E. Goulandris 

 and N. Critikos on earthquakes in 'Greece during the 

 yearsi 19 12-14. The total number of shocks recorded 

 is 1366, giving an unusually high annual average for 

 so small a country. Two destructive earthquakes (on 

 January 24, 1912, and October 17, 1914) were felt over . 

 the greater part of Greece and ruined many places, 

 the one in the south-east of Cephalonia and the north 

 of Zante, the other in and around Thebes. Both 

 occurred without any warning fore-shocks, and were 

 followed by a large number of after-shocks (the Thebes 

 earthquake by 712 within a year), several of them strong 

 enough to add to the ruin wrought by the principal 

 shocks. On November 23 and 27, 19 14, and January 27, 



1915, destructive earthquakes were felt in western Greece 

 and the Ionian Islands, the epicentres being respec- 

 tively near the south-east and north-west coasts of 

 Santa Maura and the north-west coast of Ithaca. In 

 a general discussion Prof. Eginitis states that, of the 

 earthquakes registered at Athens from 1900 to I9i4» 

 733 occurred during the night (6 p.m. to 6 a.m.) and 

 611 during the day; but he suggests that to prove the 

 greater night-frequency, a longer series of records 

 would be required. 



The strong earthquake which disturbed the Midland 

 counties on January 14, 19 16 (Nature, vol. xcvi., 



1916, pp. 572, 601), is described by Dr. C. Davison, 

 in the Geological Magazine for July (vol. vi., 1919, 

 pp. 302-12). The earthquake occurred at 7.29 p.m., 

 and was sensible over an area of about 50,200 square 

 miles. It originated in two distinct foci, one about 

 two miles north-east of Stafford, and the other about 

 one and a half miles north-west of Eccleshall, the 

 distance between them being eight or nine miles. The 

 vibrations from the two foci coalesced along a narrow 

 band crossing between them and at right angles to 

 the line joining them. As this band is slightly concave 

 towards the west, and lies nearer the western focus, 

 it follows that the eastern focus was first in action, 

 and that the impulse at the western focus occurred 

 before the vibrations from the other had reached it. 

 The earthquake was thus a twin earthquake. The 

 relations between the Stafford earthquake and the 

 twin earthquakes of Derby in 1903, 1904. and 1906, 

 and those of Leicester in 1893 ''*"<^ ^904' ^re con- 

 sidered, and it is suggested that the crust at some 

 depth must be corrugated in two systems of perpen- 

 dicular folds about seventeen miles in wave-length. 



Le Temps of .August 27, in an article on the newly 

 founded Institut d'Optique, gives some interesting 

 figures on the growth of the optical industry in France 

 during the war. These indicate that the output of 

 instruments suitable for military purposes increased 

 about ten times between 1914 and 1918. The supplies 

 of optical glass did not present so great a cause for 

 anxietv as in this countrv, for before the war, with 



