(3] Thermal proper t ies of petrole um produ cts, NBS Misc. Pub . J\I97 (1929 An a nalysis has been made of t he absorpt ion ,bands of v ario us g~asses. by calcula ti?n of t he inte rnal t ransm ittances and surface losses. The waveleni1; t hs,. Ill ~ICrons , assocIated wi th broad a bsorp tio n bands ha ve been m easured , a nd t he a ctIve vIbratll;g grou ps cau smg t he a bsorp tion are a s follows : 2.7, CO2 ; 2.75, OH ; 2.75, CO2; 2. 9, OH asso Cl at~d ; 3.5, C O~--; 3.65, (N 0 3-) ; 3.8, Si -O bond ; 4. 0, C0 3--; 4.15, (N 0 3-) ; 4.25, CO2; 4.45, SI-O b?ncl ; a nd 4.7, OH associated . The g rea tes t lo s~ of infra red e neygy fo r a num be r of glasses IS cau sed by surface losses, rathe r tha n by tr ue m te rnal a b orptlOn.