414 
Proceedings of Royal Society of Edinburgh, [july 18, 
Series VIII. — Same arrangement of apparatus. 
Molecular 
Gram. weight. 
•173 ferric chloride gave 
28 ‘5 c.c., at 
0° 0 . 
and 760 mm., 
giving 
135-7 
•093 
16-0 „ 
3 3 
3 3 
3 3 
129-6 
•120 
19-3 „ 
3 3 
3 3 
3 3 
138-6 
•076 ,, „ 
12-0 „ 
3 3 
3 3 
3 3 
140-7 
•145 iodine ,, 
18-7 „ 
3 3 
3 3 
» 3 
1731 
•171 „ 
20-6 „ 
3 3 
3 3 
3 3 
185-5 
•070 sulphur ,, 
22-8 „ 
3 3 
3 3 
3 3 
68-5 
'055 ,, ,, 
18-0 „ 
3 3 
33 
3 3 
68-0 
The ferric chloride was sublimed immediately before use, but its 
extremely hygroscopic nature renders it highly probable that the 
vapour would contain hydrochloric acid. 
The iodine indicates the dissociation of its diatomic molecules, as 
has already been shown by V. Meyer. 
Sulphur again used as a check. 
The values obtained for the molecular weights from the above 
experiments may be thus tabulated : — 
Values. Molecular formula 
Experimental. 
Theoretical. 
indicated. 
Sodium, 
. 25-5 
23 
Na 
Potassium, 
. 37-7 
39 
K 
Mercury, 
. 203 
200 
Hg 
Sulphur, 
. 67-3 
64 
s 2 
Iodine, 
. 179-3 
169 
(I 2 + 2I) 
Caesium iodide, 
. 267 
260 
Csl 
Caesium chloride, . 
. 179-2 
168-5 
CsCl 
Rubidium iodide, . 
. 221-6 
212*3 
Rbl 
Rubidium chloride, 
. 139-4 
120-8 
RbCl 
Potassium iodide, . 
. 184-1 
164 
KI 
Silver chloride, 
. 160-8 
143-5 
AgCl 
Lead chloride, 
. 262-7 
278 
PbCl 2 
Manganous chloride, 
. 132-3 
126 
MnCl 2 
Ferric chloride, 
. 136-1 
162-5 
FeCl 3 " 
Chromic chloride, 
. 154-9 
159 
CrCl 3 
Cadmium bromide, 
. 242-2 
272 
CdBr 2 
Cadmium iodide, . 
. 251-1 
366 
(Cdl 2 + Cd + I + I) 
Mercuric sulphide, 
. 161-8 
155 
(2Hg + S 2 ) 
Mercurous chloride, 
. 193 7 
2Hg + Cl 2 = 157 1 
Mixtures of Hg + Cl 2 
Mercuric chloride, 
. 155-6 
Hg + Cl 2 = 135-5 J 
with some HgCl 2 
The platinum vessel after the first experiment seemed to have 
no action whatever on the vapours of potassium and sodium, and 
the tables above given contain the results of every experiment made 
