116 J. P. Cooke—Atomic Weight cf Antimony. 
smaller atomic weight of chlorine, it requires in this last case a 
larger replacement to produce a corresponding change of per- 
centage composition, yet still the amount required to make all 
the difference in question is very small; so that, when we come 
to sum up the supposed completed results (as on page 47), it 
might easily be covered up by slight inaccuracies of the 
analytical work. An easy calculation will show that the sub- 
stitution of but ;',°, of one per cent of oxygen for the equiva- 
lent amount of chlorine would reduce the per cent of this last 
element in the chloride from 47-020, corresponding to Sb=120, 
to 46-608, which corresponds to Sb=122; and such a substitu- 
tion would result from the absorption of only 1,4, milligram of 
water by each gram of the chloride. The composition of the 
material would then be as follows :— 
Composition OF ANTIMONIOUS CHLORIDE WITH 745, PER CENT OF 
O wHEN CL=35°5 anp Sp=120. 
RmONteRiLait. Sou ces. celui. 22 a aii 26606 
MpeGR swodid. ress ee Ca eo ae ee 
BRNNIONG Sia. 8 a a ee hl eee 
100°000 
Now it will be seen by referring to the tables, on pages 47 and 
48, that these percentages do not differ from the mean of the 
results of our previous analyses as much as these results differ 
among themselves; and we therefore determined to repeat these 
analyses, hoping that the experience we had acquired in both 
chlorine and antimony determinations would now enable us to 
obtain results sufficiently sharp to show evén the small ditfer- 
ences of composition which the substitution in question would 
produce. 
termined. For this purpose, we used first crystallized SbOCl, 
tages. Th 
decomposition began between 167° and 175°, but was not com- 
ing both stages, chloride of antimony sublimed; and there was 
left in the nacelle at the close of the process beautiful crystals 
