OF COBALT SULPHATE—MORRISON. 483 
column, the differences between the observed and calculated 
densities. 
Eeteeniace of Density at 200 C. 
anhydrous salt Difference. 
in ‘solution, Observed. Calculated, 
6507 1.00552 | 1.00553 | + 0.00001 
1.5324 1.01535 | 1.01537 + 0.00002 
1.7368 1.01766 1.01765 — 0.00001 
2.4265 1.02541 \: 1:025385 — 0.00006 
BLO 1.02954 | 1.02924 — 0.00030 
5.0252 1.05498 | 1.05435 — 0.00063 
8.0207 1.09047 | 1.08778 — 0.00269 
Subjoined is a more exact empirical formula with tabulated 
results. The smallness of the co-efficient of p’?,shews that the 
concentration-density curve is practically a straight line to nearly 
2.5 per cent. 
Formula: D, =.99827 + .01109 p +.00005 p’. 
ra oO 
Beneentiage ot Density at 200, C 
anhydrous salt Difference, 
in solution, Observed, Calculated, 
6507 | 1.00552 1.00550 — 0.000C2 
1.5324 1.01535 1.01538 + 0.00003 
1.7368 | 1.01766 1.01768 + 0.00002 
2.4265 1.02541 1.02548 + 0.00007 
2.0009 | 1.02954 | 1.02943 -— 0.00012 
5.0252 1.05498 | 1.05525 + 0.00027 
8.0207 —  1.0904'7 | 1.09044 — 0.00005 
I know of only two determinations of the density of Cobalt 
Sulphate solutions with which mine can be compared. Nicol* 
gives 1.04303 as the specific gravity at 20° C, relatively to water 
at the same temperature, of a solution containing half a molecule 
* Phil. Mag. (5), XVI, (1883), p. 122. 
