August io, 191 6] 



NATURE 



493 



iginal theory is to be preferred on those 

 , rounds. 



Prof. J. P. Iddings, "The Petrology of some South 

 Sea Islands and its Significance" : — 



The islands of Tahiti, Moorea, Huaheine, Raiatea, 

 Tahaa, Bora Bora, of the Society group, and Hiva-oa 



id Nukahiva, of the Marquesas, were visited in order 



1 ascertain whether the volcanic rocks composing 

 them are of such a character that they support the 

 theory of isostacy, which demands that the deep por- 

 tions of the earth's crust, or the lithosphere, under 

 the Pacific Ocean should consist of heavier material 

 than that underlying the continent of North America. 

 It was found that the volcanic rocks of these islands 

 are noticeably heavier on the average than the igneous 

 rocks occurring in various parts of the American con- 

 tinent. Each of the islands visited was found to be an 

 extinct basaltic volcano, considerably eroded, and 

 partly submerged beneath the sea. 



Prof. J. J. Stevenson, '"Coal Formation": — 



The doctrine that the fossil fuels from peat to 

 anthracite are a continuous series has been the subject 

 of renewed discussion within recent years. The author 

 felt compelled to make serious investigation to free 

 himself from doubts aroused by the statements of some 

 authors. The general study has advanced so far as to 

 ' justify presentation of the first part of his monograph. 

 The plan adopted is to discuss the fuels in order of 

 age, beginning with peat and closing with the Palaeo- 

 zoic coals. The first part considers peat and the 

 Tertiary coals ; the second will consider the Mesozoic 

 and the Palaeozoic coals. The author hopes to make 

 evident the inherent probability of the doctrine that, 

 in spite of difference in plant materials, the coals 

 throughout form a connected series, not merelv in 

 mode of accumulation, but also in phvsical structure 

 and in chemical composition. 



Mr. G. Scatchard and Prof. M. T. Bogert, ".\ New 

 and very Sensitive Indicator for Acidimetr^' and Alkali- 

 metr\- and for Determining Hydrogen Ion Concentra- 

 tions between the limits of 6 and 8 on the Sorensen 

 Scale " :— 



The authors have discovered that dinitrobenzoylene 

 urea is an unusually sensitive indicator, and one which 

 can be prepared easily, in any desired amount, from 

 anthranilic acid. It changes from colourless to 

 greenish-yellow with a change in hydrogen ion con- 

 centration from IO-* to lo-*, the development of the 

 colour following regularly the decreasing concentration 

 of hydrogen ion. It is very little aflfected by neutral 

 salts or proteins, and not at all by the ordinary bio- 

 logical preservatives, chloroform and toluene. The colour 

 does not fade perceptibly in two days, and does so but 

 very slightly in a week. It therefore promises to be 

 very useful in the measurement of hvdrogen ion con- 

 centration of biological or other liquids in this impor- 

 tant range, for which the previously known indicators 

 are not very satisfactorv. 



Dr. F. W. Clarke, "The Inorganic Constituents of 

 Marine Invertebrates " : — 



It is a commonplace of geology that many lime- 

 stones are formed from the remains of marine 

 animals, such as corals, molluscs, crinoids, etc. Some 

 of these limestones are magnesian, some are phos- 

 phatic, and others are of the ordinary type, consisting 

 chiefly of calcium carbonate. They were originally 

 deposited at the bottom of the sea, and their composi- 

 tion depends upon the composition of the organisms 

 which formed them. The present investigation has 

 for its purpose to determine what each group of 

 organisms contributes to the sediments ; and in order 

 to answer this question nearly 250 analyses have been 

 made of the shells or skeletons of marine inverte- 

 brates, covering a range from the Foraminifera up 

 to the Crustacea, and including also the coralline 

 NO. 2441, VOL. 97] 



' algae. It was already well known that corals and 

 moUuscan shells were composed almost entirely of 

 calcium carbonate, and that fact has been verified. 

 The shells of one group of brachiopods, however, con- 

 sist largely of calcium phosphate, and that substance 

 is also abundant in the Crustacea. These animals, 

 I and also vertebrate skeletons, contribute phosphates 

 j to the sediments. The Foraminifera, Alcyonaria, sea- 

 fans, echinoderms, and calcareous algae, with some 

 I minor groups or organisms, contain much magnesia, 

 j and thereiore aid in the formation of magnesian lime- 

 ! stones. Curiously enough, the amount ot magnesium 

 j carbonate in any' series of organisms varies with the 

 I temperature of the water in which the creatures lived, 

 i being small in cold and large in warm waters. A 

 I sea-urchin from Greenland, for example, contained 

 6 per cent, of magnesium carbonate, and one from 

 near the equator contained more than 13 per cent. 

 In certain algae from the West Indies 25 per cent, was 

 found. Furthermore, some organisms have their cal- 

 cium carbonate in the form of aragonite, and others 

 consist of calcite. The aragonitic organisms are all 

 non-magnesian, while the magnesian forms are aU- 

 calcitic. The data obtained in this investigation have 

 been applied to the study of coral reefs, which owe 

 their composition to all the creatures living upon 

 them, and not to the corals alone. In fact, the corals 

 are often of less importance than their associates. 



Dr. W. Duane, 'Some Relations between Matter 

 and Radiation " : — 



It is known that the impacts of atoms of electricity 

 against atoms of ordinary matter produce radiation. 

 Mr. Hunt, Dr. Webster,' and the author have been 

 investigating the relations between the energy of the 

 atom of electricity and the frequency of the radiation 

 it produces. The most striking facts discovered are 

 that in the case of the so-called general radiation the 

 energv required is strictly proportional to that fre- 

 quency, and in the case of the so-called characteristic 

 radiation the energy required is larger than in the 

 preceding case and not always proportional to the 

 frequency. High-frequency vibrations are associated 

 with the central parts of an atom of matter, in which 

 the electromagnetic field is very strong. In order to 

 reach a p>oint in an atom of matter where a given 

 frequency of vibration is produced the atom of elec- 

 tricitv must have at least enough energy to over- 

 come a certain force of repulsion acting between them. 

 If we follow out the line of reasoning and apply ivlax- 

 well's distribution law and what has been called the 

 fourth power law to the case of the atoms of elec- 

 tricity flying about in a hot body owing to its thermal 

 agitation, we arrive at an equation for the distribution 

 of energy in the spectrum that represents the facts 

 with considerable precision. These laws discovered- 

 by experimental investigation have a practical bearing 

 on X-ray phenomena also. They indicate what must 

 be done in order to produce those very high-frequency 

 radiations that hitherto have been obtained from radio- 

 active substances only. 



Dr. L. A. Bauer, "Relation between Changes in 

 Solar .\ctivity and the Earth's Magnetic Activity, 

 1902-14 " : — 



No criterion of solar activity has been found to syn- 

 chronise precisely with any quantitv used as an index 

 of the earth's magi^etic actrvitv'. Thus, for example, 

 the maximum magnetic activity in i8q2 preceded the 

 maximum sun-spot activity of that period bv a vear. 

 So again the recent minimum magnetic activity of the 

 earth seems to have occurred in 1912. whereas the 

 minimum sun-spot activitv did not take place until 

 iqi^. or a year later. Then the amount of magnetic 

 activity is not necessarily commensurate with that of 

 solar activity, whatever measure of the latter be 

 used. When the comparisons between the solar data 



