No abstract

Certain relations between the specific volume and composition of glasses of the soda-silica series have previously been rep orted. Additional glasses were made in the same series and also in the potash-silica and soda-potash-silica series. The glasses were analyzed a nd their densities measured. Analysis of the new data suggests tha t the sp ecific volume-composition relations change definitely at compositions approximating those of eutectics, instead of at those of simple molecular ratios, as previously reported.

A study has been made of the transmittance of near infrared energy by a number of binary glasses. Of the systems studied, the lithia-silica and lead oxide-silica were found to have the highest transmittance of cnergy ill the range of wavelengths from 3.0 to 5.0 micron s. Thc' t rallsmittance of lithia-silica is compared with that of 1.he other alkali-silica glasses. Values of transmittance are given for lead silicate glasses of highcr lead eontellt than have been previously reported in the literature.

The infrared transmittance of some calcium aluminate and germanate glasses has b ecn measured out to 6 microns. The range of compositions of the calcium alum inate glasses was CaO , 26.7 to 52 .0 pOl'cent, and A1z03, 28.2 to 49.6 perccnt. Barium oxide, BeO, Bi20 3 • La20 z, MgO, a nd PbO were added in varying amounts up to a maximum of 36.0 percent for anyone constitucnt. These calcium alumi nate glasses are good infrared t ransm itters but show a prominent water absorption band at 2.9 to 3.0 m icrons. This absorption ca~ be decreased somewh at by means of a dry air t reatment of the melt. Thcse glasses have a st rong tendency toward devitrification .Ge rmanium oxide is a good glass-fo rmer. Its glasses have about the same infrared t ransmi ttance as the calcium aluminate glasses in the absence of ox ides such as Si02 and BcO, " ' hich absorb in the '1.5-to 5.5-micron region .

All curves demonstrate the reproducibility which can be attained with the apparatus.A study has been made of the transmittance of near-infrared energy by a number of binary glasses. Of the systems studied, the lithid-ailica and lead oxide-silica glasses were found to have the highest transmittance of energy in the range of wave lengths from 3.0 to 5.0 microns. The transmittance of lithid-silica glass is compared with that of the other alkali-silica glasses. Values cf transmittance are given for lead silicate glasses of higher lead content than previously reported in the literature.