1 64 



NATURE 



[May 2, 19 1 8 



OUR BOOKSHELF. 

 A Course in Food Analysis. By Dr. A. L. Winton. 



Pp. ix + 252. (New York: J. Wiley and Sons, 



Inc.; London: Chapman and Hall, Ltd., 1917-) 



Price 75. net. 

 This is a useful introductory work for students 

 who have had preliminary instruction in general 

 chemistry and are commencing- to learn the prin- 

 ciples of food analysis. The author has arranged 

 his subject-matter in a manner suitable for class 

 work during a course extending over forty labora- 

 tory periods of four hours each. In his experience 

 multiple pieces of apparatus, such as Kjeldahl 

 digestion and distilling stands, are most conveni- 

 ent when designed for twelve determinations — that 

 is, for six students, each carrying out du'phcate 

 experiments ; and the same number of students is 

 also a convenient one to use on the same day such 

 apparatus as the polariscope, refractometer, or 

 Westphal balance. Hence in the text provision 

 is made for students to work in groups of six, if 

 so desired, and the methods can be suitably allotted 

 to avoid duplication of expensive apparatus. 



General information is given upon, and labora- 

 tory work mapped out for, the various classes of 

 foodstuffs — dairy products, flesh foods, cereal 

 foods, sugars, fats, vegetables, fruits, flavourings, 

 and beverages. The general matter indicates the 

 nature and composition of the foodstuff dealt with, 

 and includes brief statements of the principles in- 

 volved in the chief methods of analysis employed 

 for examining it. In the laboratory work prescrilDcd 

 there are detailed instructions for carrying out the 

 commoner estimations. These include experiments 

 with the polarimeter, refractometer, tintometer, 

 and colorimeter ; nitrogen estimations ; determina- 

 tions of alcohol, saponification numbers, iodine 

 values, and so forth. A useful chapter is one 

 devoted to the microscopic examination of vege- 

 table foods. 



The book is written primarily for American 

 students, but the English user will find no diffi- 

 culty arising from that fact — except perhaps for 

 an occasional phrase such as "Hamburg steak" 

 or "salt-mouthed bottle." As an introduction to 

 more comprehensive works the volume can be 

 confidently recommended. C. S. 



Instruments de Musique : Le Telharmonium. By 

 Julien Rodet. Pp. 96. (Paris : Gauthier, Villars', 

 et Cie, 1917.) Price 3.50 francs. 

 This little book is characteristic of the clear ex- 

 position of a well-informed French author when he 

 has thoroughly mastered the subject. All the 

 phenomena of sound are briefly dealt with in such 

 a manner that he who runs may read. The chap- 

 ters include the production and propagation of 

 sound, a short discussion of the laws of vibration 

 of cords, plates, and tubes, the intimate nature of 

 musical sounds, and a study of musical scales. 

 Then follows a summary description of the more 

 common instruments of music; this chapter will 

 be of great use to the amateur who desires to 

 know the principles on which his favourite instru- 

 NO. 2531, VOL. IO1I 



ment is constructed. The last chapter is on a 

 new instrument, the tel-harmonium, and is the 

 novel part of the book; it is the description of an 

 electric organ by which, and by electrical means 

 alone, a synthesis is possible of any musical sounds 

 however complex. The tones so produced are de- 

 veloped by telephone. Alternating currents pro- 

 duce electric generators of tone, and these are 

 superposed on the diaphragm of a telephone. A 

 keyboard controls the tones of seven generators, 

 and by resistance arrangements the intensity of 

 any generator may be modified. In this way it is 

 said that the qualities of the chief instruments of 

 the orchestra, such as the clarinet, the oboe, the 

 cor anglais, the violoncello, and others, can be 

 reproduced with such accuracy as to satisfy the 

 musical sense of a musician who is unaware of the 

 origin of the sounds. Evidently the manipulation 

 of the instrument must be difficult. J. G. M. 



LETTERS TO THE EDITOR. 

 [The Editor does not hold himself responsible for 

 opinions expressed hy 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 Nature. No notice is 

 taken of anonymous communications.] 



Pope Innocent VIII. and Witchcraft. 



In the issue of Nature for April 11, p. 113, is an 

 erratum which corrects a statement made in Nature 

 for April 4, p. 82, regarding Pope Innocent VII. and 

 witchcraft. It is stated that Pope Innocent VIII. in 

 1484 "gave the sanction of the Church to the popular 

 beliefs concerning witches." In the cause of historical 

 truth it must be stated that Pope Innocent VIII., by 

 his Bull " Summis desiderantes affectibus " (1484), 

 must be considered to affirm the reality of the alleged 

 phenomena of witchcraft. But the Bull pronounces 

 no dogmatic decision, and the Pope does not wish 

 anyone to believe more about the reality of witchcraft 

 than is involved in the utterances of Holy Scripture. 

 The immediate effects of the Bull have been greatly 

 exaggerated. The expression, "gave the sanction of 

 the Church," is, therefore, Inexact, and, being inexact, 

 is unscientific; it needs much qualification. 



A. L. Cortie. 



Stonyhurst College, April 18. 



[The reference in Nature was from an article by 

 Dr. E. Withington in "Studies in the History and 

 Method of Science," reviewed in our' issue of April 4. 

 Dr. Withington sends the following remarks upon 

 Father Cortie's letter. — Ed. Nature.] 



The Pope's Bull is printed as preface to all editions 

 of the "Malleus maleficarum." It was taken as 

 authoritative by Catholic inquisitors, and, presumably, 

 by most of the faithful. This is what ordinary Eng- 

 lish people would understand by " the sanction of the 

 Church " ; those who in future denied " the reality of 

 the alleged phenomena of witchcraft" would contradict 

 an affirmation of its supreme Pontiff. 



The writer did not intend to suggest that such beliefs 

 are current among Catholics of the present day or 

 form part of Catholic dogma. E. Withington. 



