Specific Volumes of Oxides. 61 



single series. He touches upon it, however, shortly, in his 

 Russian ' Principles of Chemistry ' (vol. ii. p. 857). We 

 have not yet been able to consult his papers on this subject, 

 published from 1858 to 1865 in the Russian ' Mining Journal.' 

 In Table I. we give an arrangement of all the oxides which 

 are at present known, in which the number of oxygen atoms 

 correspond to the numbers of MendelejefFs groups. Some of 

 these numbers have been obtained from estimations made by 

 us by means of a very accurate method, which has been already 

 described and used by one of us *. 



Table I. — Specific Volumes of the Oxides. 



Groups 



I. 



IT. 



III. 



IV. 



V. 



VI. 



VI. 



Series. 



iR 2 0. 



1R 2 2 . 



^E 2 3 . 



|E 2 4 . 



i^ 2 o 5 - 



^E 2 6 . 



§E 2 7 . 



1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



11 



12 



H 10 

 7 Li 

 11 Na 11 

 17 K 



Cu 12 

 (21) Eb 



•Agl4 

 (25) Cs 



Au(18) 



8-£e8 

 12 Mg 12 

 18 Ca 



Znl4 

 22 Sr 



Cdl6 

 28 Ba 



■*Hg'l9 



195 



A113 

 18 Sc 



Ga(17) 

 23 Y 



In 19 

 25 La 



"ff(23) 



40? C 

 Si 23 



20 Ti 

 -(23) 



23 Zr 



Sn22 

 26 Ce 



"Pb'27 



21 Th 



N 



P30 

 26 V 



As 31 



30 Nb 

 Sb42 



31 Ta 

 Bi42 



O 



S41 

 37 Cr 



Se — 

 33 Mo 

 Te — 



32 W 



Ng?t 

 56 U 



F 

 CI 

 Mn 

 Br 



I 



Preparation and Specific Gravity of Lithium Oxide. — The 

 lithium oxide used for the sp. gr. determinations was prepared 

 by strongly heating pure lithium carbonate with a slight excess 

 of charcoal. Lithium oxide is formed according to the equation 



Li 2 C0 3 +C = Li 2 + 2CO. 



This mode of preparation, however, is not to be recom- 

 mended, because the Li 2 O dissolves platinum. In our obser- 

 vations we estimated the sp. gr. of the insoluble residue, and 

 made a correction for it. 



Mean sp. gr. of Li 2 O at 15° C. (corrected for insoluble 

 residue) = 2-102; sp. vol. = 7'12. 



We attempted to prepare Li 2 in a pure state by heating 

 the nitrate in a silver basin ; but we obtained a very impure 

 product containing Li 2 C0 3 and silver. 



Specific Gravity of Bismuth Pentoxide. — A sample of hy- 

 drated Bi 2 5 was obtained from Mr. M. M. P. Muir, and heated 

 to 120° C. until it ceased to lose weight. 



* Thorpe and Watts, Joiirn. Chem. Soc. Feb. 1880, p. 102. 

 t This place will be probably occupied by the metal Norvegium, Ng= 

 214, if it forms, besides the oxide Ng 2 3 , a peroxide of the formula Ng0 3 . 



