340 



SCIENCE. 



[N. S. Vol. XXIV. No. 611. 



Frankly it seems to us that the work is be- 

 yond these outsiders, but we are sure that 

 those who are competent will find it a work 

 of much value. X. D. 



Kurzes Lehrtuch der organischen Chemie. 



Von Professor Dr. A. Bernthsen. Neunte 



Auflage, bearbeitet in gemeinschaft mit Dr. 



Ernst Mohr. Braunschweig, Fr. Vieweg 



und Sohn. 1906. Pp. xxii + 638. 



The approval with which this book has been 

 received is indicated by the fact that it has 

 reached its ninth edition and has been trans- 

 lated into English, Russian and French. 

 This success is well deserved. Within a com- 

 paratively small compass it gives a remark- 

 ably comprehensive oversight of the funda- 

 mental principles and of the important com- 

 pounds of organic chemistry. The most im- 

 portant change in this edition is the addition 

 of a third division called * Heterocyclic Com- 

 pounds,' though a considerable portion of the 

 material in this division was formerly given 

 under the division called ' Benzene Deriva- 

 tives,' but in this edition named ' Isocyclic 

 Compounds.' The aliphatic compounds are 

 still called ' Methane Derivatives,' as in former 

 editions. 



On p. 70 Schorlemmer's classification of 

 parafiins as normal, iso-, meso-, and neo- 

 paraffins is still given, although the last two 

 classes are never mentioned in current litera- 

 ture and have been practically forgotten by 

 most organic chemists. It is a pity we have 

 no means of eliminating imnecessary and 

 little used terms of this sort. 



The most characteristic and valuable fea- 

 tures of the book are the clear, concise state- 

 ments given at the introduction of each new 

 class of compounds, presenting the most im- 

 portant methods of preparation for the class 

 and the facts on which our knowledge of the 

 structure of the characteristic group of the 

 class is based. The fault of the book, if it has 

 one, lies in the brief description of an exces- 

 sive number of compounds, far beyond the 

 possibility of memory for any one. The effect 

 must be bewildering and discouraging to the 

 beginner. W. A. Noyes. 



DISCUSSION AND CORRESPONDENCE. 



AN UNUSUAL METEOR. 



To THE Editor of Science : On page 151 of 

 your issue for August 3, Mr. E. E. Davis, 

 of Norwich, N. Y., describes a very interest- 

 ing meteor train observed by him about 5 :30 

 or 6 P.M., when traveling between Cortland 

 and Elmira, N. Y. The changes in his own 

 location during the fifteen minutes must have 

 had an appreciable influence on the appear- 

 ance of this trail, but will scarcely alter our 

 general conclusion that it was a typical case 

 illustrating and settling a matter that has 

 caused a little speculation among students of 

 the subject. If a meteor leaves a visible 

 train behind it we are apt to think that this 

 is a series of luminous particles, lying in a 

 straight or gently curved line, and that they 

 will, by reason of unequal gravity, resistance 

 of the air and possibly winds in the upper 

 atmosphere, drift along unequally, so that 

 the straight trail may gradually become irreg- 

 ular. This may be true in some cases, but it 

 is incredible that any plausible movement in 

 the thin upper air should affect the course of 

 the scattered luminous particles. They must 

 be considered as moving, with rapidly dimin- 

 ishing velocity, under the influence of three 

 forces — namely, their initial momentum, the 

 attraction of gravitation and a very gentle re- 

 sistance from the atmosphere. In most cases 

 the initial momentum is mainly that due to 

 the straight-line motion of the original meteor ; 

 but in some cases this meteor may be revolv- 

 ing on its axis in a manner quite analogous to 

 the less rapid rotation of a comet's nucleus, 

 and just as the comet of 1875 sent out a series 

 of tails from its revolving nucleus, so with 

 the streams of material issuing from these 

 rapidly revolving meteors. The diagrams 

 submitted by Mr, Davis would indicate that 

 five rotations were made in that portion of its 

 track represented by his third curve; the 

 motions of the particles outward from the 

 meteor's track were so slow that it made a 

 barely appreciable sine curve, or a broadening 

 of the track, in his first and second curves, 

 but a very large jagged sine curve in his sixth, 

 or last^ curve. This latter broadening re- 



