We present a 21-cm emission-absorption study towards extragalactic sources in the Canadian Galactic Plane Survey ( CGPS ) .
We have analyzed H I spectra towards 437 sources with S _ { \nu } \geq 150 mJy , giving us a source density of 0.6 sources per square degree at arcminute resolution .
We present the results of a first analysis of the H I temperatures , densities , and feature statistics .
Particular emphasis is placed on 5 features with observed spin temperatures below 40 K .

We find most spin temperatures in the range from 40 K to 300 K. A simple H I two-component model constrains the bulk of the cold component to temperatures ( T _ { c } ) between 40 K and 100 K . T _ { c } peaks in the Perseus arm region and clearly drops off with Galactocentric radius , R , beyond that .
The H I density follows this trend , ranging from a local value of 0.4 cm ^ { -3 } to less than 0.1 cm ^ { -3 } at R = 20 kpc .
We find that H I emission alone on average traces about 75 % of the total H I column density , as compared to the total inferred by the emission and absorption .
Comparing the neutral hydrogen absorption to CO emission no correlation is found in general , but all strong CO emission is accompanied by a visible H I spectral feature .
Finally , the number of spectral H I absorption features per kpc drop off exponentially with increasing R .