234 J. P. Cooke on the Law of Definite Proportions 
validity of the explanation of the variation in composition here 
advanced. 
It is worthy of remark that while the curve of variation may 
be said almost to demonstrate that the law of definite proportions 
may be disturbed in its action, it also most clearly sustains the in- 
tegrity of the law itself; for, as may be seen on inspection, the 
chemical force is sufficiently strong to retain the curve of Sb Zn2 
parallel to the axis of ordinates through a variation in the men- 
struum of nearly five per cent., and it is only when the excess of 
antimony present in the alloy exceeds six per cent. that the force 
which it exerts becomes strong enough to disturb the action of 
the law. What the nature of the disturbing force is must be for 
the present a matter of theory. Iam inclined to think that it is 
mony ani 
retain the calculated composition under.a considerable variation 
esure que p augmente jusqu’ a p=~@ , 0 
It will be noticed that the difference between these needles 1s 
precisely the same as the difference between the crystals of Sb 
Z4ns containing a small and a large amount of zinc, and I think 
i + 
