TEANSPAEENCT OF VAEIOUS BODIES. 
867 
Table I. {continued). 
Name of substance. 
Thickness, in inches. 
Termination 
of spectrum. 
Relative 
lengths of 
spectra. 
Remarks. 
Acetic Acid 
Glacial, liquefied 
Sat. soln. 0'75 in. 
112-5 
l6-0 
Spectrum ends abruptly. 
Acetate of Soda 
144-5 
48-0 
Acetate of Potash 
113-5? 
17-0? 
48-0 
Acetate of Ammonia 
144-5 
Acetate of Baryta 
115-5’ 
19-0? 
19-0? 
34-0 
I Very faint brownish tinge in 
J liquid. 
Acetate of Lime 
115-5? 
Acetate of Lead 
130-5 
Tartaric Acid 
127-5 
144-5 
31-0 
- 
Tartrate of Soda : 
48-0 
Tartrate of Potash 
144-5 
48-0 
Rochelle Salt (NaO, KO, 1 
CaH.OJ / 
Tartar Emetic (KO, SbO 1 
CsH.OJ / 
Citric Acid 
>> 
144-5 
131-5 
133-5 
48-0 
35-0 
37-0 
18-0 
Oxalic Acid 
114-5 
Oxalate of Potash 
117-5 
124-5 
21-0 
Oxalate of Ammonia 
27-0 
60-0 
55-0 
16-0 
Sugar-candy "1 
Milk-sugar j 
Gum-arabic 
60 grains in 200 
grains of water. 
Mucila^’e. 
156-5 
151-5 
113-5? 
Slightly opalescent. 
Silicate of Soda 
Sat. soln. 0‘75 in. 
0*54 
108-5 
12-0 
Faraday’s Optical Glass 
101-5 
5-0 
Pale yellow. 
Flint-glass 
0-68 
105-5 
9-0 
16-0 
Window Sheet-glass 
0*07 
112-5 
Hard Bohemian Glass 
0*18 
114-5 
18-0 
Plate-glass 
0*22 
111-5 
15-0 
Crown-glass 
0*74 
106-5 
10-0 
Greenish. 
Thin Glass for Microscope ... 
0-009 
116-5 
200 
The photographic impression of each spectrum in every case quoted in this Table com- 
mences at 96 '5, and the number inserted in the Table in the second column of figures 
indicates the point at which the most refrangible rays transmitted by the compound 
under examination ceased. Tlie numbers in the third column of figures represent the 
length of the spectrum, the unit of the scale being one millimetre. 
9. In the majority of cases of saline compounds in the foregoing Table the results 
given are those obtained by forming a saturated solution of the compound in distilled 
water, and decanting the liquid after it had become clear by standing. It is not advisable 
to filter in these cases, as the introduction of minute quantities of certain compounds, 
especially of some of organic origin, greatly impairs the transparency of the liquid to the 
rays which produce chemical action. 
The solution, duly prepared, was then placed in a small trough made by cutting a 
notch in a piece of plate-glass f inch in thickness, the sides of the trough being com- 
pleted by thin plates of polished quartz, which were pressed by means of bands of 
