Notices respecting New Books. 325 



Professor Odling, with Laurent, Gerhardt, Kekule, and others, 

 regarding double decomposition as the great type of chemical action, 

 enlarges the usual definition of it so as to include the direct union of 

 two elements, the substitution of one element for another, the break- 

 ing up of a compound into its elements, and the liberation of a single 

 element in the free state. 



Compound radicals are regarded by our author as not necessarily 

 existent in bodies, but as molecular groupings capable of transference 

 from one body to another. Thus substances known to be mutually 

 related in derivation and behaviour are capable of being viewed as 

 related to one another in constitution also. 



The general considerations conclude with an account of crystallo- 

 graphy, of the various states in which chemical substances occur, 

 and of atomic volume, atomic heat, and the diffusion of gases. 



In the systematic description of the elements and their compounds, 

 hydrogen, as the great typical element, comes first, the other ele- 

 ments, beginning with the non-metallic, being considered in order 

 according to the gradually increasing complexity of their relations to 

 hydrogen. An excellent feature of the volume is here apparent, 

 namely, the strict order which is invariably followed in treating each 

 subject ; but this feature becomes still more marked when our author 

 passes on to the consideration of the " monhydric elements." He 

 gives us the requisite information about each element in the same 

 manner: — I. Distribution. 2. Preparation. 3. General Properties. 

 4. Relations. And at the end of each group of elements, such as 

 that which includes chlorine, bromine, iodine, and fluorine, we have 

 a useful summary of their general properties and relations. The 

 remainder of the volume is occupied by the dihydric and trihydric 

 elements and their compounds, — the dihydric elements being oxygen, 

 sulphur, selenium, and tellurium : and the trihydric, nitrogen, phos- 

 phorus, arsenic, antimony, and bismuth. In the summary of the 

 nitrogen group, with which Part I. concludes, we have some notes 

 on " Mixed Types," and the following interesting contrast between 

 the parallel oxacid compounds to which chlorine, sulphur, and phos- 

 phorus respectively give origin : — 



Monhydric. Dihydric. Trihydric. 



HC1 H 2 S H 3 P 



HCIO CI 2 SO Cl 3 PO 



HCIO 2 CI 2 SO 2 H 3 PO 2 



HCIO 3 H 2 SO 3 H 3 PO 3 



HCIO 4 H 2 SO 1 H 3 PO 4 



A few remarks, in conclusion, as to the nomenclature of the work 

 under review. Prof. Odlinghas made but few and slight alterations 

 in the commonly received names of chemical compounds : the exam- 

 ples given below illustrate some of the. more conspicuous changes : — ■ 



Chloronitrous gas NO CI, becomes nitrous chlor-aldehyd. 



Terchloride of phosphorus . . CI 3 P, becomes phosphorous chlor-aldehyd. 



Oxychloride of phosphorus . . CI 3 PO, becomes phosphoric chlor-aldehyd. 



Sulphochloride of phosphorus CI 3 PS, &ec6mes*sulpho-phdsphoric chlor-aldehyd. 



Chlorosulphurous acid CI 2 SO, focomes'sulphurous chlor-aldehyd. 



