The story of Pittsburgh: Glass

Bibliographic data

Multivolume work

Identifikator:: 1831622599

Document type:: Multivolume work

Title:: The story of Pittsburgh

Place of publication:: Pittsburgh

Publisher:: First National Bank

Year of publication:: 1919-1930

Collection:: Economics Books

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Volume

Identifikator:: 1831623056

URN:: urn:nbn:de:zbw-retromon-239768

Document type:: Volume

Title:: Glass

Volume count:: Vol. 1, nr. 5

Place of publication:: Pittsburgh

Publisher:: First National Bank

Year of publication:: 1920

Scope:: [ca. 16] Seiten

Digitisation:: 2022

Collection:: Economics Books

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Chapter

Document type:: Multivolume work

Structure type:: Chapter

Title:: Glass

Collection:: Economics Books

complete the equipment of the city, are large sales palaces, such as are to be found in European manufacturing centers, for the display of glass and other manufactures, the whole year round. Such modern methods of display would attract buyers from all over the country and from foreign countries. MANUFACTURE OF GLASS It has been said by an eminent authority on the sub- ject, that glass is a compound of various elements chem- ically combined, and yet it is not a true chemical compound, for the reason that it is not combined in definite proportions, as are many other chemical compounds. We may say, in short, that glass is but little more than vitrified sand. If we could obtain a temperature sufficiently high, we could make glass from sand alone. That this is not done in practice is because of the difficulty of getting a tem- perature sufficiently high to vitrify the sand, and also for the reason that we could not get vessels that would withstand the heat. Nothing short of the intense heat of the electrical furnace will melt sand alone. So to make glass com- mercially we are obliged to use an alkali in connection with the sand to be able to flux or vitrify it in an ordinary temperature, or such as can be maintained with the ordi- nary fuel at our command. In practice we use an alkali— preferably, carbonate of soda or potash. In connection with these two materials we have to add for a base, either lime or the oxide of lead. We use the nitrate of soda because it also has high fluxing properties, and has a tend- ency to make the “batch,” as we term it, boil; or, in other words, to set up a violent agitation which facilitates the melting. So we can say that ordinary glass is a double silicate of soda and lime; or, if we make the finer qualities, in which we use potash and lead, in that case it is a double silicate of potash and lead. So that sand, or, technically speaking, silicic acid, with lime and nitrate of soda, are the main constituents of ordinary glass; while sand and potash, with the oxide of lead. are the main constituents

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