GO Notices respecting New Books. 



At page 68 we read, " The compound, for example, generally- 

 known under the name of Dutch liquor, G a H 4 Cl 2 , reacts upon water 

 in the following manner : — 



G a H< CL + H., 0= 2 CI H + C 2 H 4 O. 

 Now, viewing this latter substance, C 2 H 4 O, as a derivative of water, 

 it is clear that C 2 H 4 , now called ethylene, has replaced two atoms of 

 hydrogen, and is therefore a binatomic body." What a capital pro- 

 cess this is for preparing oxide of ethylene — upon paper, and what a 

 pity that it does not answer equally well in sealed tubes ! 



On page 232 we are told that " the compounds of nitrogen with 

 hydrogen are three in number, viz. amidogen, ammonia, and ammo- 

 nium, and have their composition represented by the following for- 

 mulae : — 



Amidogen NH 2 



Ammonia NH 3 



Ammonium NH 4 ." 



A more misleading statement than this could not easily be put 

 before the student ; for not only are the first and last of the three 

 substances named completely unknown, but the whole analogy of 

 the ascertained combining properties of nitrogen is against even the 

 possibility of their existence, the most characteristic of all these 

 properties being that, with elements of the hydrogen-class, nitrogen 

 unites in only one proportion, that namely of which ammonia is an 

 example. But our author habitually pays little regard to fine-drawn 

 distinctions between substances which are well known as having a 

 material existence, and those which are at best the convenient fic- 

 tions of past or present theoretical systems. For instance (p. 256), 

 he tells us that " There are seven known oxides of sulphur, all of 

 which possess the properties of acids. The name and atomic compo- 

 sition of each is given in the subjoined Table : — 



Sulphurous acid , . S0 2 



Sulphuric acid S0 3 



Hyposulphurous acid S 2 2 



Dithionic acid (Hyposulphuric) S 2 5 



Trithionic acid S 3 5 



Tetrathionic acid S 4 5 



Pentathionic acid S 5 5 . 



The hyposulphurous and pentathionic acids are instances of poly- 

 meric bodies, or of such as have the same percentage composition, 

 but different atomic weights." At page 478 occurs another example 

 of the same kind : we there read, " The oxides of carbon are six in 

 number, and of these all but the first are possessed of acid characters. 

 They are — 



Carbonic oxide CO 



Carbonic acid C0 2 



Oxalic acid H0~ C 3 + 2-HO 



Khodizonic acid 3 HO, C 7 7 



Croconic acid HO, C 5 4 



Mellitic acid HO, C, 3 ." 



