,82 



NA rURE 



[April 20, 1905 



I 



prizes, he assures us, makes the ornithologist 

 "despise common bird-life," and look only for 

 rarities ! 



Concerning the toucan and hornbill, lie writes : — 

 " The Almighty — speaking reverently — seems to have 

 made certain animals and birds {sic) in a spirit of 

 fun, or at least in a sportive mood"!! And this, 

 too, in spite of a statement on a previous page to the 

 effect that with " an ordinary beak " the toucan would 

 be unable to procure the fruit on which it feeds, and 

 that, in consequence, " the Almighty, in His wisdom, 

 has provided it with a 'beak-hand'. . . ."! 



We confess we do not like this book; where it is 

 not mischievous it is puerile. The illustrations could 

 not possibly be worse. \V. P. P. 



I'he Elements of Chemistry. By M. M. Pattison 

 Muir. Pp. xiv + 554. (London : J. and .\. Churchill, 

 1904.) Price 10s. 6d. net. 



It is somewhat difficult to understand for what class 

 of reader this book is intended. In style and treat- 

 ment it is not well adapted to beginners, yet in its 

 descriptive matter it is quite elementary. Probably it 

 will prove of greatest service to mature students of 

 other subjects who wish to gain some acquaintance 

 with the principles of chemistry without intending to 

 study the science practically. The author tells us in 

 his preface that his object has been " to present some 

 of the fundamental facts, generalisations, principles 

 and theories of chemistry, lucidly, methodically, and 

 suggestively." In this he has had a certain measure 

 of success, but the general impression left by the book 

 is that in its construction substance has been sacri- 

 ficed to form. When, for example, the author tells 

 us (p. 8g) that weighed quantities of the basic oxides 

 BaO, CaO, K„0,"Na„0, have been combined with 

 weighed quantities of the acidic oxides LO,, N,Oj, 

 P,0., P^Oj respectively, and that analysis showed the 

 resulting products to be BaLO,, CaN,^)^, K,PO,, and 

 Na,PO^, we are inclined to doubt the statement, and 

 also to doubt the wisdom of adducing imaginary 

 experiments in confirmation of a formal rule. On 

 p. 252 we find the equation 



"Na,0-1-N,05 (heated) =2NaN03." 



We wonder if the author tried the experiment ; the 

 practical instruction to heat would almost indicate 

 that he had. 



Richard Jefferies : his Life and Ideals. By H. S. 

 Salt. New edition. Pp. vii+119. (London; .\. C. 

 Fifield, 1905.) Price is. 6d. net. 



The fact of a new (and cheaper) edition of this work 

 being called for may be taken as an indication of 

 the iiold the writings of the great pioneer of the true 

 tvpe of nature-study have taken on the popular mind. 

 In the preface, the author emphasises his opinion that 

 the real claims of Jefferies to literary immortality are 

 based on his later works of the type of " The Story 

 of My Heart"; but there can be no doubt, as the 

 author himself is fain to admit, that " The Game- 

 keeper at Home " and " Round about a Great Estate " 

 are the volumes which have made the name of 

 Jefferies a household word. Biographers and 

 eulogists mav make what efforts they please to alter 

 the verdict of the public ; but in such cases the old 

 maxim that the vox populi is vox dei still holds 

 good. To the great majority of readers Jefferies will 

 continue to be known solely by his inimitable (if some- 

 times Icxj realistic) descriptions of rural life and 

 character. .Although in small type, the new edition 

 of his life is well printed on good paper. R. L. 



NO. 1851, VOL. 71] 



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 wilh the writers of, rejected 

 manuscripts intended for this or any other part of Nature. 

 No notice is taken of anonymous communications.] 



Historical Note on Dust, Electrification, and Heat. 



Your readers may remember that in July, 1883, I penned 

 a letter to your columns (vul. .x.xviii. p. 297) describing 

 some observations which the late J. W. Clark and myself 

 had recently made ; among others, one to the effect that 

 a small ejectrical discharge into a smoke-laden atmosphere 

 rapidly dissipated the smoke by coagulating the particles. 

 Some time afterwards we found that the observation had 

 previously been made by a Mr. Guitard, and printed in the 

 Mechanic's Magazine for 1850 — a reference to this fact 

 being actually contained in that great compendium of 

 electrical information, Wiedemann's " Galvanismus 

 U.S.W.," so that it must be regarded as fully " published." 



I now write to say that during the labour of indexing, at 

 the koyal Society, Prof. McLeod has come across a much 

 earlier instance of the same observation, showing that the 

 phenomenon was really discovered in 1824. An extract 

 from Prof. McLeod's letter runs as follows : — ■ 



" In the course of our indexing we have come across 

 a paper that may interest you, if you do not already know 

 of it. It is by Hohlfeld, " Das Niederschlagen des Rauchs 

 durch Elektricitiit, " Kastner, .-^rchiv Naturl., ii., 1824, 

 205—206. It is very short ; he refers to the increase of the 

 fall of rain and hail after a flash of lightning, and de- 

 scribes how he filled a globe with smoke and led into it 

 a pointed wire connected to an electric machine which 

 caused the smoke to settle." 



If any importance attaches to the subject, it must de- 

 pend upon the successful application, in future practice, of 

 so conspicuous a result. Hitherto the only practical appli- 

 cation of the same sort of principle has been the 

 " coherer " used in some systems of wireless telegraphy, 

 of which Prof. Branly's porphyrised-copper powder-smears 

 and iron filings-tubes may be regarded as the earliest 

 examples. 



Perhaps, however, I may direct attention to my paper 

 to the British Association (Report for 1885, pp. 743 et seq.), 

 in which this electrical action on visible particles is likened 

 to chemical agglomeration into molecular aggregates, lead- 

 ing to an electrostatic theory of chemistry, a matter worthy 

 of, and now receiving, sustained attention. 



May I further take the opportunity of amending an over- 

 sight? Mr. Clark and I came across the fact of the elec- 

 trical deposition of smoke while we were experimenting 

 on Tyndall's dark plane or dust-free space seen near hot 

 bodies in illuminated air, a matter to which attention had 

 been directed by a notable investigation of Lord Ray- 

 leigh's (see Nature for 1882, vol. xxviii. p. 139). It turned 

 out afterwards that we were not the only experimenters 

 on this subject, Lord Rayleigh's letter having also roused 

 the attention of that eminent specialist in dust researches, 

 Mr. John Aitken, of Edinburgh ; and though we pub- 

 lished our account of dust-free spaces due to heat in the 

 Philosophical Magazine for March, 1884, his corresponding 

 investigations and explanations were published a month 

 or so earlier in the Transactions of the Royal Society of 

 Edinburgh, vol. xxxii. p. 239 ; and to him accordingly 

 belongs priority in such parts of this matter as are not 

 covered by my preliminary letter to Nature of the July 

 previous, which doubtless includes many things that were 

 practically anticipated by Lord Rayleigh himself. 



I mention this now because I have been rather too apt 

 to forget it, and have omitted to mention Mr. Aitken's 

 name when, if I had had all the circumstances consciously 

 before me, I should certainly have mentioned it. In par- 

 ticular, in a history of the coherer principle contained in 

 my little book on" Wireless Signalling," third edition, 

 p. 75, I speak of the explanation of the dust-free space 

 round a hot body, due to a molecular bombardment, as 

 having been first published by ourselves, instead of by 

 Mr. .Mtken, whose name, I regret to say, does not appear ; 

 this is the oversight I wish to amend. 

 .■\pril 12. Oliver Lodge. 



