172 Reviews. [Jan., 



With the more common constituents of our earth, the means of 

 identification are comparatively simple. Supposing a mixture contain- 

 ing all these, six general tests divide them at once into six groups, and 

 thus one great step is taken towards their individual recognition. 

 The further steps are indeed not so simple, but slowly and surely the 

 student proceeds until he has recognized every one of these bodies by 

 some decisive reaction. 



But the detection of a body which is made in a qualitative analysis, 

 and its complete separation and determination by weight in what is 

 called a quantitative analysis are two very different matters. The first 

 is a comparatively simple proceeding ; to the latter there is sometimes 

 an insuperable obstacle, and it becomes necessary to infer the amount 

 of a substance by the difference remaining when everything else in a 

 given weight of a mixture has been determined. 



The reader thus sees that analytical chemistry is no child's play. 

 To pursue it successfully requires no little skill in manipulation, no 

 little perseverance, and above all things, no little patience. To 

 students gifted with these, few pursuits are more fascinating; but 

 without them, few pursuits probably are more disappointing. 



With regard to Dr. Noad's book we have but little to say, and that 

 little must be in commendation. To those who commenced the study of 

 chemistry fifteen or twenty years ago, few books are better known than 

 the excellent manual which Dr. Noad wrote, we believe, for the So- 

 ciety for the Diffusion of Useful Knowlege. The present work is the 

 analytical part of the former book brought up to our present know- 

 ledge of the subject. The quantitative part is a compilation of all the 

 best processes which have been devised, made by one thoroughly ac- 

 quainted with analysis ; and although the book is stated to be " for 

 the use of students," this part will serve as a work of reference to 

 those whose students' days may be said to have passed. 



THE ASTEONOMICAL OBSERVER* 



It is not the good fortune of many who take a great interest in 

 Astronomy to possess an equatorially-mounted telescope ; and to such 

 as have only the use of an instrument mounted on a plain stand, the 

 observation of objects invisible to the naked eye presents some diffi- 

 culties. By the compilation of this Hand-book, Mr. Darby has ren- 

 dered an essential service to amateur astronomers, and more especially 

 to those who cannot afford an equatorial ; for the most useful feature 

 of the work, and an original one, is that directions are given for find- 

 ing objects with a plain telescope, the stars visible to the naked eye 

 serving as pointers to the invisible objects. 



The work consists of a catalogue of the constellations with the 

 most interesting telescopic objects, — nebulae, clusters, and double stars, 



* ' The Astronomical Observer. A Hand-book to the Observatory and the 

 Common Telescope.' By W. A. Darby, F.R.A.S. London : Hardwicke. 1864. 



