CERTAIN CHARACTERISTICS OF GLASS-FIBER AND THE STRUCTURE OF GLASS A. F. Zak Direct methods of structural analysis have not yet enabled a clear conception of the structure of glass to be worked out. Many questions in connection with glass structure are still open to argument. In view of this great importance is attached to various physicochemical investigations which might throw light upon some in dividual aspects of this highly complex problem Ante. Among these investigations, the study of glass solubility under the effects of corrosive media is of definite interest. These investigations did not, however, produce the expected results. In the reaction of glass with difficult to obtain reliable data on those processes which do take place under these circumstances make it ous agents, the soluble constituents are not entirely eliminated from it, while secondary reaction To a certain extent, the acid treatment of sodium borosilicate glasses provides an exception. It is well known that when a number of glasses of this system are reacted with acid, the sodium borate constituent is al most completely driven off, leaving only the predominantly siliceous framework which contains nearly 96%0 SiOz A method of making products from quartzoid glass which possesses a number of valuable characteris ics, has been developed on this basis, Many years investigation of the structure and properties of sodium borosilicate glasses, both primary and suitably treated, have made it possible to make a definite assessment of the structure of these glasses,Accord ing to I. B Grebenshchikov and others, sodium borosilicate glasses consist of a silicate framework which is pre dominantly filled in with sodium borates. The approximate values of the chemically inhomogeneous region It has been postulated that by analogy with the sodium borosilicate glasses, the glasses of other systems also have a microheterogeneous structure. These opinions however have met with a number of objections. The unique dissolution of the sodium borosilicate glasses has been ascribed to the alternating structure of the boron compounds Glass fiber has a very small thickness, a few microns in all, and therefore, when it is reacted with cor roslve substances the individual constituents dissolve fairly quickly, the reagent penetrates into the interior of the fiber, while the destruction products can be almost entirely removed from it. This allows the degrees of cohesion of the separa te constituents within the glass structure to be determined. An investigation of the way that fibers of different compositions dissolve, and their structure after chemical treatment, should give some very valuable information on the structure of glass fiber and of glass. a study of the solubility of sodium borosilicate fiber confirmed that boric and sodium oxides can be oo mpletely removed from it by treatment with acid, whereby a siliceous fiber is produced containing over lo SiOz. In contrast to solid glass, the removal of the sodium borate constituent from the fine fiber takes place without any kind of preliminary heat treatment, and a good deal quicker. This shows that the way in which glasses of a borosilicate composition dissolve is not dependent on the peculiarities of the structure of boron compounds. A silicate fiber can also be produced by the acid treatment of sodium silicate with different contents alkaline metals. Here, the alkaline metals can be quickly driven off from the fiber leaving a silicate fiber containing over 99 Sioz. This shows that the bond between the alkaline metal cations and the silicate frame work is very weak. It can be assumed that when fiber produced from sodium silicate is reacted with acid, an ion exchange of Na* for H+ takes place. On heating the fiber to 500-600.C the moisture is driven off and the pores begin to close. The adsorption The moisture content in the porous fiber corresponds to the quantity of sodium oxide driven off fromCERTAIN CHARACTERISTICS OF GLASS-FIBER AND THE STRUCTURE OF GLASS A. F. Zak Direct methods of structural analysis have not yet enabled a clear conception of the structure of glass m be worked out. Many questions in connection with glass structure are still open to argument. In view of this, great importance is attached to various physic0chemtcal investigations which might throw light upon some in￾dividual aspects of this highly complex problem. Among these investigations, the study of glass solubility under the effects of corrosive media is of definite interest. These investigations did not, however, produce the expected results. In the reaction of glass with various agents, the soluble constituents are not entirely eliminated from it, while secondary reactions make it difficult to obtain reliable data on those processes which do take place under these circumstances. To a certain extent, the acid treatment of sodium borosilicate glasses provides an exception. It is well known that when a number of glasses of this system are reacted with acid, the sodium borate constituent is 'al￾most completely driven off, leaving only the predominantly siliceous framework which contains nearly 96~ SiO~. A method of making products from quartzoid glass which possesses a number of valuable characteris￾tics, has been developed on this basis. Many year's investigation of the structure and properties of sodium borosilicate glasses, both primary and suitably treated, have made it possible to make a definite assessment of the structure of these glasses, Accord￾lng to I. B Grebenshchikov and others, sodium borosilicate glasses consist of :a silicate framework which is pre￾dominantly filled in with sodium borates. The approximate value~ of the chemically inhomogeneous regions have also been defined. It has been postulated that by analogy with the sodium borosillcate glasses, the glasses of other systems also have a microheterogeaeous structure. These opinions however have met with a number of objections. The unique dissolution of the sodium . borosilicate glasses has been ascribed to the alternating structure of the boron compounds. Glass fiber has a very small thickness, a few microns in all, and therefore, when it is reacted with cor￾rosive substances the individual constituents dissolve fairly quickly, the reagent penetrates into the interior of the fiber, while the destruction products can be almost entirely removed from it. This allows the degrees of cohesion of the separate constituents within the glass structure to be determined. An investigation of the way that fibers of different compositions dissolve, and their structure after chemical treatment, should give some very valuable information on the structure of glass fiber and of glass. A study of the solubility of sodium borosilicate fiber confirmed that boric and sodium oxides can be completely removed from it by treatment with acid, whereby a siliceous fiber is produced containing over 99% SiO 2. In contrast to solid glass, the removal of the sodium borate constituent from the fine fiber takes place without any kind of preliminary heat treatment, and a good deal quicker. This shows that the way in which glasses of a borosilicate composition dissolve is not dependent on the peculiarities of the structure of boron compounds. A silicate fiber can also be produced by the acid treatment of sodium silicate with different contents of alkaline metals. Here, the alkaline metals can be quickly driven off from the fiber leaving a silicate fiber containing over 99% SlOg.. This show~ that the bond between the alkaline metal cations and the silicate frame￾work is very weak. It can be assumed that when fiber produced from sodium silicate is reacted with acid, an ion exchange of Na + for H + takes place. The moisture content in the porous fiber corresponds to: the quantity of sodium oxide driven off from it. On heating the fiber to 500-600~ the moisture is driven off and the pores begin to close. The adsorption 608