F. W. Clarke on ” Atomic Volume . Compounds. 181 
the metal and sitet . “eg free state; so that it is prob- 
able that some oxyds follow the same rule. 10-4 being the 
highest number for aye yer it likely that that is the 
true value for this element in those oxyds corresponding to 
the above mentioned sulphids. 
Now, two sulphids appear to follow this rule, viz: NaS 
and K,S, whose sp. gr., given by Filhol, Pe 2 respectively 2-471 
and 2°180, At vols, 81:6 and 61°6. Now ——— 6 204: 
na 2458) 4158, 
=53°4. If these theoretical atomic volumes 
are true, fe the sp. gr. of Na,S will be 2549, or 0-078 greater 
than the value found ; while that of K,S will be 2 ‘059, varying 
0-071 from Filhol’s number. These variations are wholly with- 
in the limits of error for such compounds. 
But the results obtained with four oxyds are more striking. 
MgO. Sp. Be 3-200, Karsten. At.vol. 12°5. St!*—12-1. Error 0-4 
CaO, $181, « 1ry, S181. “ 0-4 
SrO. “ 4°611, Filhol. * 904, Sl a99'3em: “ 6-05 
Al,O,. “ 8°928,Ebelmen. “  25°9, *2@t8000_95-8.« 9-1 
As oxyds of barium, sodium, and potassium, do not follow 
this rule. 
One more regularity traced, and I am done. If my views 
concerning multiple relations are correct, and all the values for 
oxygen and sulphur are multi a of the lowest, then we must 
expect that compounds formed by the union of these elements 
will have atomic volumes which are also multiples. Now, sul- 
phuric anhydrid, SOx, has, according to Buff, the sp. gr. 1-909 
at 25°, and according to ‘Baumgartner 1-975. Its atomic vol- 
ume, then, is from 405 to 41:9. And 41°6 is precisely four 
The chloride, it gest oe iodids of the “i metals and 
silver, seem to afford a ar example. In of m 
vious papers I showed that ey a values for Ch Br, an om 
ey liquid ba em were almost exact multi tiples of his num- 
‘H, poravens ss J judg ng from analogy, it is likely 
that these elements in their unds would follow a 
similar rul the — ie Ag, have 
saree volumes which do not v eatl m multiples o 
n accordance with what we should expect, their 
cumstance cannot be ascribed to accident. 
I present a tabular view of this regularity, 
