420 
ME. W. CEOOKES ON THE VISCOSITY 
Table Y. (continued).—Log. dec. of carbonic oxide between pressures of 1000 M and 
6 ‘5 M. Temp. 15° C. 
re-jsure. 
Log. 
R pulsive 
M 
decrement. 
radiat 
1000 ( = 0• 76 m.m.) 
0-0947 
2 
829 
0-0945 
3 
629 
0-0936 
4 
474 
0-0925 
5 
397 
0-0921 
6 
200 
0-0910 
13 
188 
0-0907 
14 
126 
0-0877 
18 
86 
0-0838 
20 
55 
0-0778 
21 
42 
0-0716 
22 
38 
0-0692 
22 
31 
0-0653 
21 
22 
0-0580 
18 
13 
0‘0474 
14 
12 
0-0448 
13 
6'5 
0-0305 
i 
684. These numbers are plotted as curves in the diagrams A, B, and C. They are 
remarkable as showing an almost complete identity with those of nitrogen on the same 
diagrams, both in position and shape. The viscosity at 760 millims. is in each case 
0T092. According to Graham the proportion between the viscosities of air and 
carbonic oxide is 0'97l, nitrogen giving the same (706). With my apparatus the 
proportion is 0'9715. 
Like that of nitrogen, the curve of carbonic oxide is seen to be vertical,— i.e., 
assuming the curve to represent the viscosity, the gas obeys Maxwell’s law,—at 
pressures between 90 millims. and 3 millims. The vertical portion in nitrogen is at a 
little higher pressure : between 100 millims. and 6 millims. 
685. The curve of repulsion resulting from radiation, shown in dots in diagrams B 
and C, is lower in carbonic oxide than in any other gas examined, and, unlike the other 
gases, there is no sudden rise to a maximum at about 40 M. At lower exhaustions 
the curve is, however, higher than it is in nitrogen. 
OBSERVATIONS ON THE SPECTRUM OF CARBONIC OXIDE. 
686 . During exhaustion observations were continued on the variations in the spectrum. 
The ordinary band spectrum is first seen with a few sharp lines terminating the bands. 
At 12 millims. pressure a sharp green line is first seen, X 515. This line rapidly 
grows brighter as exhaustion continues, and then fades out; it is last seen at a pressure 
of about 0 - 9 millim. This line is probably the bright oxygen line, the wave-length of 
which is given by Plucker at X 514 - 4. 
. At a pressure of 2'8 millims. the spectrum agrees in appearance with the “ Carbon 
No. 2 ” in Watts’s ‘ Index of Spectra.’ 
At 553 M the bands between the sharp lines appear to be breaking up into masses 
of fine lines. 
