ON THE MOLECULE OF WATER. 
181 
or three times nine parts, or five times nine parts, etc., but in every case by eighteen 
parts, or some multiple of eighteen parts, as instanced in the following examples, which 
might be increased indefinitely:— 
Formation of Nitro-henzol . 
c 6 h 6 
+ 
hno 3 = C g H 5 (N0 2 ) + 
II 2 C" 
or 
2HO 
2C 2 H 6 
+ 
Decomposition of Zinc-ethyl. 
ZnII 2 0 2 = Zn(CJL) 2 + 
2H 2 C" 
or 
4110' 
3C 7 H 6 0 
+ 
Formation of Ilydro-henzamide. 
2H 3 N = C 21 H 13 N 2 + 
3H 2 C" 
or 
6HC' 
h 3 po 4 
Decomposition of Pentachloride of Phosphorus . 
+ 5I4C1 = PCI- + 4H.O" 
• o * z 
or 
8H0' 
Again, in the great majority of direct compounds which water forms with other 
bodies, the combining water necessarily constitutes 18 parts, or some multiple of 18 
parts ; and when two or more bodies differ from one another by the quantities of water 
they respectively contain, the differential quantity always amounts to 18 parts or some 
multiple of 18 parts, thus :— 
c 10 h 16 
Turpentine. 
^10^16 • 
HoO 
or 
C 10 H ls O 
Monhydrate. 
C'loP-16 * 
2h:o 
or 
^10®20^2 
Dihydrate. 
^10^16 • 
3H 2 0 
or 
^10^22^3 
Trihydrate. 
CNH 
Prussic Acid. 
CNH . 
HoO 
or 
CNH.,0 
Formamide. 
CNH . 
2H 2 0 
or 
CNH.Oo 
Formate of Ammonia. 
Several chemists, during what may be termed the transitional stage of their views, 
were accustomed to represent the molecule of water by the formula HoO'.,, in which O' 
stands for 8 parts of oxygen, instead of by the formula H 2 0", in which 0" stands 
for 16 parts by weight of oxygen. But the use of this formula really showed an 
imperfect appreciation of the grounds upon which the abandonment of the simpler 
formula HO' was based; for if the molecule of water is to be represented with two 
proportions of hydrogen, because its hydrogen is divisible into two parts, invertendo 
it must be represented with but one proportion of oxygen, because its oxygen is 
indivisible. Now that the oxygen of water is indivisible is acknowledged alike by those 
who use the formula H 2 0" and those who use, or rather used, the formula H 2 0' 2 ; and 
such being the case, the representation of the oxygen of water by the expression 0' 2 is 
quite unwarrantable, for the conception of two inseparable proportions of oxygen having 
each the value 8, amounts after all to that of a single indivisible proportion of oxygen 
having the value 16. 
That the oxygen not only of water but of all other well-defined oxygenated molecules 
always amounts to 16 parts, or some multiple of 16 parts, is abundantly evident. For 
the composition alone of the great majority of oxygenated bodies, prevents them from 
being represented save with 16 or some multiple of 16 parts of oxygen, just as the com¬ 
position of chloroform prevents its being represented save with 12 parts of carbon ; and 
as the composition of ethylamine prevents its being represented save with Id parts of 
nitrogen. With regard to the remaining oxygenated bodies, their mere composition 
would allow them to be represented with only 8 or some odd multiple of 8 parts of 
oxygen, but their several relations to other bodies belonging to the more numerous class 
prevents them from being represented with so small a quantity; just as the relation of 
triethylamine to ethylamine and diethylamine prevents it from being represented with 
less than 14 parts of nitrogen, though from its mere composition it might be represented 
with only 4’7 parts of nitrogen. 
From this it follows, that when two or more bodies differ in composition from one 
another by the proportions of oxygen they respectively contain, that difference always 
amounts to 16 parts or some multiple of 16 parts, as shown in the following series:— 
