554 



NATURE 



[June 22, 191 1 



LETTERS TO THE EDITOR. 



[The Editor does not hold himself responsible for opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part of tiATVKE. 

 No notice is taken of anonymous communications.] 



The Solar Eclipse of April 28. 

 TiiK failure of thp observers at Vavau to obtain a satis- 

 factory view of the eclipse is very unfortunate, and the 

 whole astronomical world will share their disappointment. 

 It is welcome news to hear thaT perfect conditions prevailed 

 at islands situated some distance from Vavau, and equally 

 well placed as regards the line of totality. 



1 have received a letter from Mr. C. L. Wragge, who 

 observed the eclipse under ideal conditions from the island 

 of Moungaone in the Tongan group. He writes to me 

 from Lifuka as follows : — 



" It was entirely successful, with a clear sky, and 

 magnificent beyond words. A lovely sketch to scale was 

 also secured by another member of my special party at 

 Lifuka — duration of totality, about two minutes. Four 

 great streamers were seen. 



" The shadow-bands rippling over the cocoanuts, and the 

 dark purplish-black of the ocean, obliterating the lovely 

 tinges of blue and green water around the coral reefs, were 

 superb. 



" The natives rushed into their houses, and came out 

 and cheered when, with a blaze of glory, the sun 

 reappeared." 



The photographs secured have been taken back to New 

 Zealand for development, but a sketch enclosed with the 

 letter shows the corona with four magnificent streamers of 

 the type characteristic of the solar sunspot minimum, and 

 also a very large prominence. The streamers and inner 

 borona are described as " silver-white," and the following 

 approximate measurements are given : — 



Highest streamer of corona, about 649,000 miles. 



Large red flame, about 217,000 miles. 



The streamers were in pairs, two extending north-east 

 and two south-west, while silver-white ridges of the inner 

 corona extended round the north-west quadrant. 



CriARLES W. Raffety. 



2 Park Hill Road, East Croydon, Surrey, June 18. 



Dinoflagellates and Diatoms on the Beach. 



In walking across the beach between tide-marks at 

 Port Erin on April 7, I noticed a greenish-brown discolora- 

 tion of the sand in places — especially along the edges of 

 the ripple-marks and other depressions — which I supposed 

 to be caused by a deposit of diatoms. The examination 

 of a sample in the laboratory soon showed, however, that 

 although a few diatoms (Navicula amphisbaena, or some 

 closely allied form) are present, by far the greater part of 

 the deposit is formed of the active little peridinian or 

 dinoflagellate Amphidinium operculatum, Clap. and 

 Lachm., which has not, so far as I can ascertain, been 

 previously recorded on the British coast. 



The innumerable specimens of Amphidinium were all 

 alive, reproducing by longitudinal fission, and very active 

 in their movements. They would leave the sand-grains to 

 which they were adhering, swim round rapidly in the 

 water, and then settle down again upon a sand-grain. 

 These dinoflagellates remained abundant on the beach at 

 Port Erin until the end of April, when the observers had 

 to return to Liverpool. During these weeks the patches of 

 discoloured sand changed a little with each tide, increasing, 

 diminishing, shifting, or even disappearing for a day, and 

 then reappearing. Samples placed in dishes of sand and 

 sea-water in the Biological Station flourished, and the 

 organisms increased so as to form a dark-coloured layer 

 over the sand, eventually rendering the water impure and 

 causing the death of the dinoflagellates. 



.\t the meeting of the Linnean Society on June i 

 I directed attention to this unusual occurrence of this 

 small Amphidinium in vast quantities, and exhibited speci- 

 mens. Two days later I was again on the beach at Port 

 Erin, and found what were apparently the same patches 

 of^ discoloured sand, but on examining scrapings with the 

 microscope saw that the deposit was now wholly com- 

 posed of a golden-yellow diatom, one of the " amphisbaena 

 NO. 2173, VOL. 86T 



group " of Navicula. I searched the beach carefi 

 between tide-marks, and examined samples from < -. 

 susf)ected patch of sand, but could find no tra< 

 .Amphidinium so abundant a few weeks b<»for 

 Navicula, which was present in April in very - 

 ties, seems completely to have replaced the 

 We have probably much to learn in regard to m- i-v^iiun^sj 

 and goings of such microscopic forms and their physic 

 logical inter-relations in connection with what may 

 called " the metabolism of the beach." 



W. A. Hekdmak. 

 Liverpool, June 12. 



A New Method of Chemical Analysis. 



Will you permit me to step outside usual practice in 

 this instance and to direct wider attention to the exception^ 

 ally brilliant and momentous work described to the Koj'i 

 Institution on Friday evening, .April 7, by its present pr 

 lessor of natural philosophy, as reported in Nature 

 June I, p. 466? Oliver Lodge. 



The author of the present note is probably one of 

 few chemists living who was originally brought up in th 

 Berzelian electrochemical theory (for which idea Berzelii 

 was indebted to Davy), and, as shown in an article pul 

 lished in 1877 (see also Arrhenius-Jubelband), he made 

 sharp distinction between elements playing the " elect 

 positive " and " electronegative " rAle. So, e.g., the 

 nection between the position of elements in Mendel^eff^ 

 periodic system and their valency was expressed thusi 

 The positive valency of the elements (towards the negatin 

 oxygen) may change between i and 8 ; the negative valenc 

 (towards the positive hydr<^en) may change between 

 and 4 only. 



But such ideas, for which I was formerly reproache 

 of being " unmodern," are very modern indeed to-day. 



This is seen from the highly interesting lecture, pul 

 lished in Nature of June 1, by Sir J. J. Thomson, " 

 New Method of Chemical Analysis " (p. 466 et seq.). 



Without referring to the results communicated in 

 lecture with anything but high admiration, I beg 

 point out that Sir J. J. Thomson finds that, when th 

 elements hydrogen and carbon had passed — original 

 positively charged — through the kathodes of his tul 

 they appear also negatively charged. This he call 

 " remarkable, for hydrogen is generally considered to 

 a strongly electro-positive element," and " the atom 

 carbon, also regarded as an electro-positive element, 

 also conspicuous on the negative side." 



I desire to remark that there is an analogy, but also 

 certain difference, between the notion " positive " ar 

 " negative " as used by the chemist or by the physicis 

 Physically, and also chemically, a positive atom carrid 

 positive charges, and the negative atom vice versa. 

 holds good of Sir J. J. Thomson's atoms (see the artic 

 and of the atoms in solutions which we chemists 

 " ions." The difference lies in the point that, as regar 

 the atoms constituting the chemical compounds, the ter 

 " positive " and " negative " have only a relative valii 

 as pointed out in the introductory lines. Hydrogen 

 positive towards chlorine in hydrogen chloride, H + C\.\ 

 and many other compounds, whereas it forms the negati 

 constituent of potassium hydride, K+H_, and other simil 

 compounds (CaH„, LaH,, CeH^, &c.). 



The physical analogy of this relativity is the zero 

 tion of hydrogen in the electrical tension series. It 

 positive compared with the " noble " metals and 

 metalloids ; it is negative compared with the " ignoble 

 metals like those of the alkalies, alkaline earths, and 

 earths. 



As regards carbon, it is positive in C+Oj. , but it 

 negative^ in Hj+C_ and in the more popular calcii 

 carbide, Ca+Co_. 



In the compounds KH, CaC„, and also in Na,+N._ 

 had already suspected latent negative chemical ic 

 Chemists will be indebted to Sir J. J. Thomson that 

 has shown their existence physically. It is interestii 

 but not surprising, that the said elements take up nega 

 charges under the conditions of his experiments. 



BOHUSLAV BR-AUNI 



Bohemian University, Prague, June 6. 



