Th e infrared spectra of gaseous tet raftu oroethylene from 22 to 52 j1. and liquid tetrachloroeth ylene from 3 to 52 j1. have been determined. Several hitherto unobserved bands were found. N ew and sati sfactory assignments, for which a detailed discuss ion is given, have bee n achieved. Th e ou t-of-plane forc e co nstants are di scussed and u sed to predict the wagging and torsion frequ encies of tet rabromoeth ylene. Tables of the therm odynamic fun ctions for tetrafluoro-and tetrach loroethy lene are prese nted .

The infra red a bsorp tion spectra of se ve n cyclop entane a nd fi ve cyclohexanes have been meas ured i n t he region from 2 to 15 microns. The s ubstances we re cyclop en tane, m e th y lcyclopen tane, 1, I-dimeth ylcyclopen tane, tmns-l ,2-di methylcyclopen tane, trans-I , 3-dimeth ylcyclopen tane, cis-l ,2-d im eth ylcyclopen tane, a nd cis, tmns, cis-l ,2,4-trimethy lcyclopen ta ne, also cyclohexa ne, meth ylcyclohexane, 1, I-dimeth ylcyclohexa ne, lmns-l ,2-dimeth ylcyclohexane, and cis-l,2-dimethylcyclohexane. The wavelengths of all t he obse rv ed absorp ti on bands are g ive n i n a table, and a graph is shown of the per cen tage t ransmission over the wave length reg ion of each s ubstance. The h ydrocarbons were highl y purified in the C hemi t ry Division a nd these spectra will be of value as a check on the puri ty of t hese co mpounds which may be ob ta ined from other sources. Also t he m ore inte nse bands serve as a mea ns of ide nt ifi ca t ion. For each substance t he bands that are best s uited fo r distinguishing it a re noted .Of special in te res t are the four dimethylcyclopen ta nes whi ch we re studi ed. The stru ct ural p osit io ns of t he s ubstit u ted meth yl groups differ only sligh tly, bu t the spectral d iffe rence is q ui te mar ke d. The infra red a hso rp tion spectra a re we ll s ui ted to show characteristic differences between isomers.The meas uremen ts were ma de w ith a Perkin -Elmer spectro mete r wi th a Ge ne ral M otor amplifier and Brown recorder. A sli t co ntrol mecha nis m is describe d in d etail. Although t he slit control gear arrangem ent is relatively simpl e, the results obtained wi th i t aloe good, The e nergy outpu t is held nearl y co nstant from 3. 5 to 14.5 m icrons .

The infra-red absorption of methylamine vapor has been measured from 2 to 18μ with a cell of 18 cm length using pressures from 2 to 55 cm. A total of nineteen bands has been observed, nine of which are assigned to fundamental vibrations. The bending vibrations of the two groups give rise to several bands in the region from 6 to 8μ. This causes considerable overlapping which makes it difficult to locate band centers and to determine band types in this region. Three bands which originate from the C – H vibrations occur at wave-lengths between 3.0 and 3.6μ. A band due to the N – H parallel valence vibration has been found at 2.98μ. The most intense band in the spectrum occurs at 12.9μ, and arises from a bending vibration of the hydrogen atoms in the amino group. The parallel vibration between the methyl and amino groups gives rise to an intense band at 9.56μ. This is a parallel band having a sharp and intense zero branch. A band also due to a bending vibration in the amino group was observed at 16μ, and from the experimental curve it can not be said whether it is parallel or perpendicular; hence definite assignment is not made. The other bands which have been observed have been assigned to overtones and combinations.

da rd wa \" clengLh s for cali b ratin g infrar ed-pri sm in str um ent s nave b een mea sured fro m t h e a bso rpLion ba nds of p olysty rene, 1, 2,4-trichlo roben zen e, a nd toluene. Several b an d s of didym ium glass h ave been ca librated for t h e nca r-infra r ed r egion , an d 27 rotat ion a llin es of t h e 3. 3-micro n b an d of m et h an e h ave been m easured.Th e wavelengths fall in Lh e reg ion fr om 0. 6 to 24 m icron s, bu t t he g reatest numb er a r c in t h e 3-to 6-m icron r eg ion . A few band s of seve ral other m ate rials are a lso give n i n t h e \\'avc!e ngth t a bles, and 11 fi gurE' S of t h e Rp ectra ma rk ed w it h t he cali braLing valu es a re i ncl ucl ed for id en t ifi ca t ion .

Many observers have studied the infra-red absorption bands of quartz and have found regions of intense absorption at 9/x, 12.5/*, 20yu and 26fx. These regions of absorption are assumed to be the fundamental frequencies of quartz. By combining these assumed fundamental frequencies six bands in the region from 3/j, to 9fx are accounted for. Also the writer has experimentally located two bands at 2.72/z and 3.18M which have not been previously observed. The frequencies of these two bands agree with two combinations of the fundamental frequencies. This gives a total of eleven absorption bands for the ordinary ray of quartz, extending from 2.72^ to 26^ whose frequencies agree, with only small differences, with the calculated values.