32 DR. GLADSTONE ON THE REFRACTION-EQUIVALENTS OF THE ELEMENTS. 
III. Alcoholic Solutions. 
Substance. 
Formula. 
Equiva- 
lents of 
alcohol. 
Specific 
gravity. 
Tempe- 
rature 
Centi- 
grade. 
fiA. 
FD- 
pir. 
Refrac- 
tion- 
equiva- 
lent. 
Potassium Alcoholate 
KC.H.O 
528 
0 915 
12-5 
1-3871 
1-3916 
1-4046 
28-22 
5355 
0-911 
205 
1 -3852 
1-3896 
1-4026 
28-03 
Iodide 
KI 
217-S 
0-799 
19-5 
1-3591 
1-3632 
1-3743 
35-1 
Sulpkocyanide . . . 
KSCN 
46-9 
0-813 
19 
1-3649 
1-3693 
1-3812 
33-7 
Sodium Alcoholate 
Copper Chloride 
NaC„ H. 0 
Cud, 
5-88 
1 1 90 
0-875 
0 961 
24 
12 
1-3807 
1-3856 
1 -4026 
1-3985 
24 61 
D 34-72 
31-72 
Cobalt ,, 
Co Of 
24-34 
0-873 
17 
1-3769 
1-3814 
1-3937 
35-04 
0-851 
12 
1 3733 
1 -3893 
33-06 
Mercury , , 
Hg Cl 
16-2 
1043 
19-5 
12 
1-3828 
1-3872 
1-4006 
3510 
20-24 
0-995 
1-3795 
1-3839 
1-3970 
36-08 
Ammonia 
NH, 
5 0 
0-780 
20 
1 3576 
1-3618 
1-3726 
8-97 
I am indebted to friends for the use of some of the above compounds. Professor 
Frank land kindly lent me the mercuric methide and the ketones; Professor Williamson 
the titanium tetrachloride, chromium oxychloride, and ethylic phosphite ; Professor 
Poscoe the vanadium oxychloride ; and Mr. Perkin the cacodvlic acid. 
Postscript, 21st March, 1870. 
Since writing the statement about the aromatic compounds under the head of carbon, 
I have satisfied myself that their exceptionally high refractive power cannot be explained 
by the higher equivalent of hydrogen. 
More recent experiments have confirmed the numbers provisionally assigned to anti- 
mony and gold, and led to some augmentation in those for didymium and zirconium. 
