44 
excess of milk of lime for about an hour, filtered whilst hot 
and allowed to cool. The salt separated out, on standing, 
in slender, white, needle-shaped crystals, generally from one 
half to an inch in length. They were sometimes obtained 
of not more than a quarter of an inch in length, and almost 
transparent, the separation not taking place until the solu- 
tion was agitated. The composition of the crystals was in 
all cases the same, and was not affected by the length of 
time they were allowed to remain in contact with the liquid. 
The crystals, dried as quickly as possible between blotting 
paper, on analysis gave the following results : — 
(а) 0-677 grm. gave 0*273 grm. CaO. 
0-442 „ „ 0-228 „ AgCl and 0-0012 Ag. 
0*307 grm. lost on heating 0*152 grm. 
(б) 0-359 grm. gave 0*144 grm. CaO. 
0-794 „ „ 0*2045 „ AgCl and 0*0245 Ag. 
T052 lost on heating 0*52 grm. 
Calculated for Found Calculated for 
CaO, CaOHCl + fH^O. 
^ _A_ 
. 3CaO, CaCL+16H. 
(«) 
(0 
Ca 
... 29*144 ... 
... 28-80 
28-77 . 
28*22 
Cl 
... 12*932 ... 
... 12*86 
12*794 . 
12*522 
0 
... 5*829 ... 
— 
— 
8*465 
OH ... 
... 6*193 ... 
— 
— 
— 
HoO ... 
... 45*901 ... 
... — 
— 
— 
Loss on heating 49*179 ... 
... 49*40 
49*47 . 
...(HoO)50*793 
100*000 
100*000 
The constitution of the salt is therefore expressed by the 
formula ^ | + On heating, two molecules of 
the salt decompose, forming SCaOd-CaClg+lSHgO. The 
difference of the proportion of the constituents according to 
the above formula, and according to that assigned by Eose, 
is therefore that corresponding to one atom of water more 
or less. As the amount of water is nearly 50 per cent of 
the whole, this constituent will exhibit the greatest differ- 
ence, namely 1*514. Accordingly, the numbers above will 
