of the Metallic Oxides. 



105 



metallic hydrates and their anhydrides, the latter having 

 generally a greater density. The density gradually and suc- 

 cessively increases as the hydrate loses its water, until it 

 attains its maximum in the anhydrides or oxides themselves. 

 For example : — 







Molecular 

 weight. 



Density. 



fMg(OHV 



Brucite 



58 



40 



99 



81 



81 



176 



158 



62 



70 



374 



178 



160 



160 



157 



121 



103 



2-34 



3-65 



2-677 



6-00 about 



560 



4325 



4-750 



1-48 



1-83 



3-6 to 4-0 



4-0 to 4-4 



5-24 to 5-28 



5-04 to 5-17 



2-35 



3-45 



4-00 



1 MgO ..". 



Periclase 



fZn(0H) o 



Crystallized 



f Crystallized 



\ Amorphous 



Acerdese 



I-Zn 



JMn 2 3 .H 2 ... 

 \Mn 2 3 



Braunite 



fB(OH), 



Crystallized 



Fused 



\B,0 3 



f 2^03.311,0.. 

 |Fe 2 3 -H 2 0: 



1 Fe,0 Q 



Limonite 



G-othite 



f Oiigiste 



\ Calcined 



1 - 1 - C 2 V 3 



V A1 2 3 .3H 2 ... 

 A1 2 3 .H 2 ... 

 ALO Q 



Hyclrargillite ... 

 Diaspore 



Corundum 





It should be noticed that a marked difference in density 

 is observed in the case of substances which are known to be^ 

 polymeric, thus : — 







Mole- 

 cular 

 weight. 



Density. 



fc 2 H 4 



(C 2 H 4 0) 2 ... 

 l((W» . 



f0 5 H 8 



l 2oH 32 



(C 5 H 10 



\ C 10 H 20 



f Acetic aldehyde 



44 



44 



88 



132 



68 



136 



272 



70 



140 



210 



0-801 at 0°. 

 0-898 „ 

 1-048 „ 

 0-998 at 15°. 

 0-652 at 11°. 

 0-8767 at 0°. 

 0-94 at 9°. 

 0-663 at 0°. 

 0-777 ,, 

 0-8139 ,; 



\ Ethylene oxide 



Diethylene oxide 



Paraldehyde , 



Isopropylacetylene 



Terebenthene 



Colophene 



Amylene 



Diamylene 



Triamylene 





Kelations similar to those which are observed between the 

 hydroxides and the oxides also exist between the latter and 

 the chlorides. The densities of the oxides of the radicals 

 C W H 2}1 are notably less than those of the corresponding 

 chlorides, and this difference is in some degree similar to that 

 between the molecular weights of these compounds, thus :■ — 



