52 



NA TUKE 



[A/ay 15, 1884 



therefore such as to suit the practical pharmacist rather 

 than the analytical chemist. The substances are described | 

 under their several Latin synonyms, in addition to the 

 French, German, English, and Spanish names. We find 

 that each preparation is described as to physical and 

 chemical properties, and then follows a very elaborate 

 examination for the presence of impurities, in addition to 

 methods of quantitative determination of the principal 

 constituents. It should be a very useful addition to the 

 pharmaceutical laboratory. 



Mr. Scott-White's volume is one of the usual little 

 books of chemical analysis tables. There seems to be 

 nothing very remarkable about it, excepting the variety 

 of types in which the formulae are printed. The book, 

 which is intended as a text-book for the various examina- 

 tions of the University of London, Oxford and Cam- 

 bridge Senior Locals, and the Kensington examinations, 

 seems well adapted for its purpose. It contains a table of 

 solubilities of common inorganic salts, which is a thing 

 students rarely make use of; and an appendix of re- 

 quirements in examinations, detailing apparatus, chemi- 

 cals, &c, necessary for most of the elementary examina- 

 tions in chemistry. 



With all our science classes and the very general spread 

 of scientific education throughout the country, it is still a 

 sad fact that the great mass of the public and even of the 

 middle-class educated public are wofully ignorant on 

 common things. Even now it is somewhat out of place 

 to talk in a drawing-room about oxygen : as to the men- 

 tion of phosphorus or selenium, or metals like platinum or 

 iridium, it is still more out of place. A great deal of this 

 ignorance— ignorance possibly occasioned by dread— is 

 doubtless caused by the very scientific science books that 

 are in common use. We are almost 'entirely without 

 books on general science that are sufficiently simple, and 

 at the same time accurate, to convey a general but correct 

 notion of ordinary substances, or to interest the ordinary 

 reader in all these things around us. Why should not the 

 properties of oxygen or phosphorus be quite as interesting 

 reading as some of the three-volume novels ? Mr. Lloyd 

 Morgan in his very small book has evidently intended to 

 supply to some extent this want by describing— not in 

 simplest language, it might have been simpler— a few very 

 common chemical and physical facts. It does not appear 

 exactly from the preface for what class of readers it is in- 

 tended, but it can scarcely fail to be useful if not interesting 

 to any lay readers. It commences with the chemistry of a 

 candle flame, and in that way passes on to the similar 

 actions taking place in animals and plants, where of course 

 carbonic acid comes into play, and we are led through car- 

 bonic acid to wood, coal, and diamonds, to the atmosphere, 

 where the physical part comes in, the pressure of the 

 atmosphere, the thermometer, and the idea of elements, 

 compounds, and mixtures. Passing on to water, we have 

 the proof of the composition of water, physical properties of 

 water, which leads directly on to the phenomena of heat. 

 Although only consisting of about 150 small pages, we are 

 led up at the end to some chemical reactions, and an ap- 

 pendix on molecules. The whole book is arranged for ex- 

 perimental purposes, although the methods of performing 

 some of the experiments are not given. It has been pro- 

 bably assumed that the experimenter should have conve- 

 niences supplied. The appendix on arithmetical questions 



seems scarcely required in such a work, but, excepting 

 this, it is certainly a step in the right direction to bring a 

 knowledge of common things into a simple and under- 

 standable shape. 



" L. M. C.'s " text-book is a sort of chemical, physio- 

 logical, and biological book, and is divided under the fol- 

 lowing heads :— Food, its composition and nutritive value ; 

 its functions ; and its preparation and treatment. It is 

 evidently got up for the purpose of preparing for the ex- 

 aminations, as it says in the introduction that a grant of 

 4J. will be given for a pass, and that payment upon the 

 results of examinations of school children are made to 

 managers. In spite of this a considerable amount of use- 

 ful information may be obtained from it, although that 

 information is not conveyed in the best possible style. 

 The descriptions of substances like bread, for instance, are 

 not by any means exhaustive. Under animal food or 

 flesh, it is stated that " animal food is composed of the 

 same materials as vegetable ; it is formed of the same 

 elements and presents the same approximate principles, 

 and contains water and mineral matters of the same kind 

 as plants." This is not very instructive. The section on 

 food and its selection will be useful, but the main object 

 of the book is evidently to prepare for the examinations on 

 this subject. 



If the spread of chemical teaching may be measured by 

 the number of small books on qualitative analysis, it 

 certainly has a great number of disciples. There is 

 nothing very extraordinary in Mr. Stoddard's book, un- 

 less it be the importance that is given to the atomicity 

 marks attached to the signs of the elements. We find 

 that iron is described as Fe" and also Fe iili , whilst chromium 

 is only put down as Cr uii . Nickel and cobalt are both 

 marked as dyad and tetrad. Only the so-called ordinary 

 elements and acids are treated of. 



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 with the writers of, rejected manuscripts. 

 No notice is taken of anonymous communications. 

 [The Editor urgently requests correspondents to keep their letter: 

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

 that it is impossible otherwise to insure the appearance even 

 of communications containing interesting and novel facts.] 



Reply to Mr. Grubb's Criticisms on the Equatorial 

 Coude of the Paris Observatory 



In continuation of my first letter I now wish, in my turn, t| 

 criticise Mr. Grubb's instrument, and to show that m all respects' 

 it bristles with inconveniences. I discuss it as it is presentee- 

 and explained by Mr. Grubb, and I wish to examine it ** 

 cessively — 



(1) From the optical point of view. 



(2) From the point of view of the mechanism employed. 

 U) From the point of view of its application to astronomy. 

 (1) The optical point of view. The system adopted by Mr' 



Grubb is much inferior to that generally used in ordinary cjiu 

 torials. The dialytic telescope only gives images free from colon 

 for the point which lies in the axis of the object-glass For all oth i 

 points images present themselves under the form of spectra wind 

 are longer as they are further from the axis. This arrangemeii 

 necessitates that the three lenses must be very exactly centre. ■ 

 which can be done with the ordinary achromatic object-gfj 

 where the two lenses are in contact in the same cell. It is «i 

 very great difficulty that this can be done in a dialytic telescope 

 While admitting, however, that it can have an optical axis commol' 

 for all the lenses of which it is composed, this centering become 

 very difficult when the images are broken by a plane mirror, th 



