402 Mr. Higgins’s Observations on Dr. Murray’s Statement 
ton’s System, by way of contrast ?—were he to attempt it, he could 
not produce a single new fact in his favour, except that of ma- 
king the particle of hydrogen as the standard weight of those of 
other bodies. 
Few as the foregoing cases which the Doctor adduces may ap- 
pear, Lavoisier’s anti-phlogistic theory, or the doctrine of Sir 
Isaac Newton respecting the laws of gravitation, might be con- 
fined to still fewer. 
We will now attend to the Doctor’s remarks on those cases, 
as he calls them. ‘* But in these statements, &c.” Nothing can 
be more glaringly unjust than this assertion, as the following ex- 
tract taken from my Comparative View will prove. After having 
shown by means of diagrams and numbers, that the one particle 
of oxygen is united to the one particle of sulphur in the atom of 
sulphurous acid, with greater force than the two particles of oxy- 
gen in the atom of sulphuric acid, in consequence of the force of 
attraction of the particle of sulphur being equally divided be- 
tween the two of oxygen, I proceeded thus: ‘‘ This seems to be 
a general law: all bodies unite with greater force to half the 
quantity of those substances to which they have an affinity, than 
to the entire ;—instance, carbonate of potash will part with a cer- 
tain portion of its carbonic acid in a moderate degree of heat, 
yet it requires a very strong heat to expel the whole. In like 
manner crystallized sulphate of potash will part with most of its 
water in a heat below ignition, but it requires a strong red heat 
to drive away the entire of its water. Thus we find, in propor- 
tion as the potash is deprived of one part of its carbonic acid, its 
power of retaining the remainder is increased: and the same 
law holds good as to the expulsion of water from the salts. I 
shall forbear mentioning several other circumstances of the like 
nature*.”” Dr. Wollaston had written a paper on this subject a 
few years ago, without any reference to what I advanced thirty 
years back: of this I have taken notice in this Magazine, vol. 51, 
page 169. Here follows another extract on the same laws ex- 
tended to metallic oxides: ‘‘ I have already shown upon what 
principle the bases of the acids retain their oxygen with less force 
when fully saturated with it than when united to a small portion. 
The same law holds good in all other combinations, and is ex- 
plicable on the same principles. Almost all bodies will unite to 
the different substances to which they have an affinity, in various 
proportions until they arrive at the point of saturation, which 
limits their power of chemical attraction. There are exceptions 
to those laws ;~—instance, the elementary principles of water will 
only unite in one proportion, so that we can never obtain it in an 
* Comparative View, pages 40, 41 ; or Atomic Theory. 
intermediate 
