74 



NA TURE 



\_Nov. 25, 1 1 



described by Giimbel occur in depths of over 2000 fathoms 

 when near to land, while a Globigerina ooze or Pteropod 

 ooze may occur in very shallow depths, in the tropics, far 

 from land. These deposits of the Draclic, being near the 

 coast, it is found that quartz predominates. The frag- 

 ments of plagioclase, orthose, hornblende, augite,bronzite, 

 mica, garnet, tourmaline, dicroite (is it not glaucophane ?), 

 magnetite, zircon, chlorite, all come from the disintegra- 

 tion of the ancient rocks which form the coast of Norway 

 and Scotland. Giimbel also finds fragments of granitic 

 rocks, dioritic rocks, S:c. Fragments of modern volcanic 

 rocks, such as lavas and pumice, are very rare when com- 

 pared with the particles derived from ancient rocks. 

 Glauconite was found in some of the specimens, and the 

 author believes that these have been transported, which 

 is quite unlikely, as large deposits of glauconite are now 

 in process of formation along the coasts of the north 

 of Scotland. The organisms — mollusks, echinoderms, 

 foraminifera, and diatoms — are all the same as those 

 usually found in partially inclosed seas like the North 

 Sea, and do not present any peculiarities worthy of note. 



The author supposes that there is a continuation under 

 the North Sea of the ancient rock-masses of Scandinavia. 

 This may be true, but the supposition can in no way 

 have been suggested by the chemical, microscopic, and 

 mineralogical examinations of the deposits of the North 

 Sea. In conclusion, Giimbel states that the sediments of 

 the North Sea prove that sandy deposits can be formed 

 alongside of clayey and marly deposits, during the same 

 time in the same sea. This conclusion has already been 

 perfectly established, and this confirmation supports an 

 interpretation generally received, which was one of 

 the first results of the examination of the Cliallengcr 

 deposits. 



The Hydrographic Office of the German Admiralty 

 have done excellent service in taking up the scientific 

 examination of the North Sea. It is a work that we 

 would like to see continued and advanced by our own 

 Hydrographic Office. J. M. 



OUR BOOK SHELF 



Chemical Aritliinetii. By Sydney Lupton, M.A., F.C.S., 

 F.I.C. Second Edition. (London: JNIacmillan and 

 Co., 1 886.) 

 We are pleased to note a new edition of this excellent 

 woik, in which several improvements have been made. 

 The hundred pages of introductory matter in the first 

 edition have been reduced by about one-half, much 

 unnecessary pure arithmetic having been cut out. The 

 1200 examples with answers are, on the whole, well 

 selected, though many of them can scarcely be called 

 chemical. A greater number of typical examples might 

 advantageously have been worked out at full length. 



The book is especially to be commended for its clear 

 and concise definitions, which are in many books very 

 loosely expressed. The differences between density and 

 specific gravity, atomic and molecular weights, for 

 instance, are explained in a manner that any student of 

 ordinary ability will readily understand. We feel sure 

 that the book will be appreciated alike by students and 

 teachers, but it will be especially valuable to teachers. 



Expert menial Clieitiistry. By C. W. Heaton, F.I.C, 

 F.C.S. New Edition, Revised. (London : George 

 Bell and Sons, 1886.) 

 Another edition of this work on experimental chem- 

 istry, adapted from the German of Dr. Stockhardt, has 



just been issued. To those students of limited means 

 who desire to work at chemistry as well as to read it — 

 and it is for those that the book is intended — it will 

 be found useful. The introduction, however, is much 

 too extensive and theoretical for beginners, and we fear 

 that many would be disheartened before reaching the 

 really experimental work. In our opinion, the book is 

 not sufficiently practical, many experiments lacking 

 detail. We would suggest that in future editions a few 

 pages be devoted to instructions in the manipulation of 

 apparatus and the working of glass. 



Part IV., which is devoted to organic chemistry, is very 

 clearly set out. The book is not sufficiently modernised 

 for these days of competitive examinations, but the 

 teacher who is desirous of encouraging his students to 

 perform simple experiments in spare moments would get 

 many valuable ideas from it. 



LETTERS TO THE EDITOR 



[The Editor does not hold himself responsible for opinions ex- 

 pressed by his correspondents. Neither can he undertake to 

 return, or to correspond ivith the writers of, rejected manu- 

 scripts. No notice is taken of anonymous communications. 



[ The Editor urgently requests correspondents to keep their letters 

 as short as possible. The pressure on his space is so great 

 that it is impossible othei~wise to insure the appearance even 

 of communications containing interesting and novelfacts.} 



The Sense of Smell 



In your issue of Septhmber 30 (vol. xxxiv. p. 521) your corre- 

 spondent Dr. Arthur Mitchell is desirous of obtaining some 

 data in regard to the sense of smell. In a p.iper presented at 

 the Philadelphia meeting of the Americin Association for the 

 Advancement of Science (1884) we have described a series of 

 experiments designed to test the delicacy of this sense. These 

 experiments, being of a preliminary character, have hitherto 

 been withheld from publication, but the following brief state- 

 ment of the results obtained may be of interest to Mr. Mitchell 

 and to olher readers of Nature. We made use of the following 

 subst.ances : — (l) oil of cloves, (2) nitrite of amyl, (3) extract of 

 garlic, (4) bromine, (5) cyanide of potassium. A series of solu- 

 tions of each of these was prepared, such that each member was 

 of half the strength of the preceding one. These series were 

 extended by successive dilutions till it was impossible to detect 

 the substances by smell. The order of the bottles containing 

 these solutions \\a% completely disarranged, and the test con- 

 sisted in the attempt to properly classify them by the unaided 

 sense of smell. The thirty-four observers who assisted in these 

 experiments were of both sexes ; the results are indicated in the 

 following table (I.) : — 



Amount detected 



The same method of investigation has since been followed by 

 one of us ' in some experiments, the results of which are given 

 in Table II. 



Amount detected 



' " Some Special Tests in Regard to the Delicacy of the Sense of Smell," 

 by E. H. S. Bailey and L. M. Powell (/"roc. Kansas Acad, o Science, 

 vol. ix.). 



