February 6, 1902] 



NA TURE 



Z^l 



Lehrbuch der Chemie und Mineralogie. By Prof. G. 



Siebert. 3 vols. Pp. viii + loi, vi + 144, vi + no; 



figs. 100, 91, 32. (Braunschweig : Friedrich Vieweg 



und^Sohn, 1901.) Price Mk. 4'25. 

 This text-book, which is intended for use in higher 

 schools, does not differ to any very remarkable extent 

 from numerous other elementary treatises on the same 

 subject. Perhaps the first volume, described as an intro- 

 duction to chemistry and mineralogy, shows the most 

 originality in treatment. In this part the begmner is 

 made acquainted with the most important chemical pro- 

 cesses, such as oxidation and reduction, and is taught 

 something of the more common chemical compounds, 

 mainly by means of experiments, of which a hundred are 

 fully described. These experiments are in most cases 

 quantitative, and involve the weighing of gases as well as 

 of solids and liquids. The laws of chemical combination 

 which receive their expression in the atomic theory are 

 thus impressed on the student by his own actual quanti- 

 tati\e results. The treatment of the mineralogy is of a 

 somewhat perfunctory character. The six systems of 

 crystals receive the usual brief and inadequate exposition 

 common to chemical text-books, and the Naumann 

 system of notation for the crystal-faces is explained, but 

 no mention is made of Miller's system. A review of the 

 most important minerals appears at the end of the volume, 

 and brief descriptions, with figures of the crystals, of 

 natural phosphates, sulphates, <S:c., are given in their 

 appropriate places in the text. The second volume is 

 devoted to inorganic chemistry, and the elements with 

 their principal compounds are treated in turn, the non- 

 metals in the order of their valencies, and the metals in 

 the usual groups. The third part deals with organic 

 chemistry. Structural formate are explained, but the 

 treatment is sufficiently elementary, as is evident from 

 the fact that the whole subject of both fatty and aromatic 

 compounds occupies less than a hundred pages. In an 

 appendix are given the descriptions of a number of 

 simple experiments illustrating the methods of production 

 and properties of some of the most important organic 

 compounds. A very brief introduction to organic and 

 volumetric analysis completes the volume. 

 Knowledge. Vol. xxiv., January to December, 1901. 



Pp. xii -H 288. (London : Knowledge Office.) Price 



8j. i>d. 

 Some of the full-page photographic plates in this volume 

 of Knowledge are very fine. Among the subjects are 

 several brilliant photographs of star clusters and nebuhi?, 

 taken by Dr. Isaac Roberts, constellation figures on 

 Greek coins, lunar photographs, life-history of a sun- 

 spot group, spectra of Nova Persei, and the solar corona 

 of May 18, igoi. Mr. E. W. Maunder has a series of 

 articles on constellation studies, in which he deals largely 

 with the poetical aspects of the sky ; Dr. Vaughan 

 Cornish has four articles on the sizes of ocean waves ; 

 Mr. G. H. Carpenter describes insects of the sea ; Mr. 

 R. Lydekker writes on a number of subjects of zoological 

 interest ; Mr. H. F.Witherby on ornithological experiences 

 in the Soudan ; and Mr. R. Lloyd Praeger on flowering 

 plants. There are numerous other articles of an in- 

 structive character. 

 A Geography of Wales. By A. E. L. Hudson, B.A. Pp. 



xii -I- 164. (London: Macmillan and Co., Ltd., 1902.) 

 This book is intended chiefly for use in Welsh schools, 

 and the general idea borne in mind in its preparation is 

 that the best foundation for a knowledge of geography 

 is the study of the land and the people of the district and 

 country m which the pupils live. The attention given to 

 physical geography and to civic affairs, such as local and 

 national government, and population and its distribution, 

 is noteworthy. There are many attractive illustrations, 

 which, with the instructive text, will serve to commend the 

 book to the attention of teachers. 



NO. 1684, VOL. 65] 



LETTERS TO THE EDITOR. 

 [The Editor does nol hold himself responsihle- for opinions ex- 

 pressed by his correspondents. Neither can he undertake 

 to return^ or to co> respond ivith the writers of rcjeciei 

 nianuscripls intended for this or any other part of NATURE. 

 No notice is taken of anonviiious communications.^ 



Fall of Mud or Dust. 



My men here noticed on Thursday last the 23rd inst. that 

 the leaves, glasses of the frames and iron work of the gates were 

 smeared with a reddish mud ; one hedge in particular they 

 described as almost covered with the substance ; and the pina- 

 fores of a cottager's children which were hanging out to dry 

 were so stained with the deposit that they had to be rewashed. 

 When the substance fell no one here knows, nor is it clear 

 whether it fell as dust or mud ; from the firm way in which it 

 has attached itself to the iron work I should think that it fell as 

 mud. 



Unfortunately, I did not hear of the event till some days after- 

 wards, and I first saw the . deposit yesterday. It was still, 

 notwithstanding a good deal of rain, to be seen on the iron 

 work, the glasses ot the frames and on leaves. I send for your 

 inspection herewith a laurel leaf, down the sides of the midrib 

 of which you will find some of the deposit in question. Possibly 

 some expert may be able to determine the nature of the deposit. 

 It does not appear to me to be silica. 



I append cuttings from local papers, showing that the phen- 

 omenon was observed elsewhere. Lawrence Weston is some 

 five miles north-east from hence, Chewton Priory some fifteen 

 miles south east, and Barry Island some twenty miles west-by- 

 south and on the other side of the Bristol Channel. 



Failand, January 28. Edw. Fry. 



From the Bristol Times and Mirror. January 21. 

 A Curious Storm. 



Sir, — I thought the readers of your valuable paper would be 

 interested to know that on Thursday morning we had what I 

 think a rather strange storm, about a quarter past seven, of 

 about 15 minutes' duration. After it got light I found quite a 

 covering of dust on the glass on the garden frames, about the 

 colour of Bath brick dust. Not having seen any account of it in 

 your paper, I thought I should like to hear if anyone else had 

 noticed it. Yours truly, 



Lawrence Weston, Henbury, January 24. A. Denham, 



From the Western Daily Press, January 28. 

 Singular Phenomenon. 

 Sir,— Seeing in your paper of yesterday's date a paragraph 

 about a mysterious led substance which fell at Barry Island on 

 Wednesday last, I write to say that a somewhat similar phen- 

 omenon occurred here. 



Wednesday the 22nd was with us very warm, with wet mist 

 only measuring o 02 of rain. Afterwards the glass and wood- 

 work of the greenhouses and frames were covered with a rust- 

 coloured dust, which has left stains on the paint. 



Yours faithfully, 

 Chewton Priory, Bath, January 26. Waldegrave. 



Change of Pitch of Sound with Distance. 

 I H.WE read with considerable interest the letter by Mr. 

 Paul R. Heyl on this subject in your issue for January 23. Speak- 

 ing off-hand, I should have agreed with Mr. West, that pitch rises 

 with distance ; but, in view of the experience of your later 

 correspondent's grandfather, I am inclined to adopt the contrary 

 view. Many years ago I was sitting with an organist friend 

 listening to a fugue on an organ— I think the player was the 

 late Mr. Thomas Adams, and the fugue one of the immortal 

 " Forty-eight" of Bach. At any rate, it was in a minor key; 

 but I noticed that the last chord was major. " Why," I asked 

 my friend, "does he end witha major chord?" "Because," 

 was the reply, "sound has a tendency to rise in a long building 

 like a church, and therefore the writer anticipated this by 

 writing his final chord with a major third." But was this 

 the reason? If the late Mr. Knauff was right, it was probably 

 to allow for the third dropping, and the chord reaching the 

 listeners as a minor chord, in keeping with the rest of the 

 piece. 



