system of Notation to express Chemical Reactions, 277 

 We have here the water-molecule of the glycol decomposed, 



its H separated into IP, H 2 • also one CI separated into CI 2 , CI 2 , 

 — these semimolecules ascending from the burnt condition and 

 descending again to it ; or they change their partners without 

 changing their potential condition. 



Pp. 430, 431. Ethyl-glycol, vapour- density measured 45 = 



C 2 H 4 0*. HO*. C 2 H 5 (C 2 H 5 ) O 2 is the formula for this given 



at page 431. 



P. 454. Butyl-glycol is isomeric with ethyl-glycol, and has the 



€ 4 H 8 1 

 same vapour-density; its formula (page 455) is jp >0 2 . 



Diethyl-glycol, Vapour-density measured 59 = C 3 H 6 2 . HO 2 . 

 € 2 H 4 (C 2 H 5 ) 2 2 is the formula for this given at page 432. 

 Glycol diacetique, vapour-density measured 



73 = CH 2 0*.C 2 H 3 O l % 



or one molecule anhydrous acetic acid united to one molecule 

 oxide of ethylene. The formula for this given at p. 433 is 



rc 2 H 4 -i 



\(C 2 H 3 0) 2 J e > 



fC 2 H 3 2 ~1 



and for the same at p. 403 is < £2jj3C 2 H 4 Q2 f • 



Appendix. 



In some educational books on chemistry lately published, 

 hydrates of metals are freely spoken of; not potassium and 

 sodium only, but of other metals as well : and the name is not 

 merely typical, or given for classification purposes, but the con- 

 stitution of the hydrated oxide is by the new school viewed (and 

 the view generally inoculated into undergraduates ?) as a molecule 

 on which a single atonfof oxygen, of hydrogen, and of the metal 



are united. Thus caustic potash is represented to be H 2 O 2 K2, 



being isomeric with HO 2 . KO 2 , which represents what is now 

 called the view of the old school. 



Mr. J. J. Griffin, in his l Chemical Recreations/ 1834, appears 

 to have first suggested this view, and he boldly announced his 

 opinion that " the hydrates of the metallic protoxides contain 

 neither protoxide nor water" If the molecule of caustic potash 



is really H 2 O 2 K 2 , it is evident that in it there is neither HO£ 

 an ultimate molecule or atom of water, nor KO 2 , an ultimate 

 molecule and atom of the protoxide. Mr. Griffin considered it 

 absurd to suppose that water can exist in a body like caustic 



