Soda-lead glass

Making glass The glass used in making art objects is soda-lead glass. It is commonly called crystal or lead glass. Its composition is mostly silica (sand), sodium oxide, and lead oxide. Soda-lead glass has excellent optical qualities. 

Molybdenum is extremely resistant to attack by molten glass up to 1 000° C if sulphur is present, and up to 1 400°C in its absence. In addition, any reaction products formed by the two materials are colourless. Consequently molybdenum is used in the production of optical and soda lime glasses. Molybdenum is, however, corroded by lead glasses which lose their gloss as a result of the interaction between the two materials. ... 

For the soda-Hme-silica glasses this is about 2-5 gm/cm for the borosilicate glasses it is very nearly 2-25 gm/cm and hardly changes with slight variations in composition. Wembley L.l. lead glass has a density of 3-08. A very dense lead glass has a density of 5-2. 

Sealing platinum into soda or lead glass. 108... 

SEALING PLATINUM INTO SODA OR LEAD GLASS... 

Fig. 3.20. Common conductivity probe for vacuum work. A couplings to shielded cables from conductivity meter 5 a B. 19 or B.24 socket fitting onto cone on observation/reaction vessel C graded-seal soda glass to borosilicate glass D shielded leads spot-welded to thick Pt wires E sealed through the soda glass probe and held together by the lead glass bead F.

Fig. 3.22. Arrangement of the leads inside the conductivity cell shown in Fig. 3.23. Cu copper wire, Sd soldered joint, W tungsten wire, SW spot-weld, Pt platinum wire, S soda glass sleeve, SS silver-soldered joint, P borosilicate glass arm fused to the cell, PtP platinum plate electrodes held together with lead glass beads L.

Fig. 3.26. The Holdcroft-Plesch observation vessel to find the conductivity and the UV spectrum of a solution (a) plan, (b) elevation. A mixing vessel also serving as conductivity cell, and burettes, Q, Q, Q PTFE taps, D Pt wire electrodes fastened together by a lead-glass bead, E terminals from screened cables leading to D, F graded-seal soda glass-Pyrex, G cone for connection to vacuum and supply lines, 1 cm and 0.1 cm quartz cells.

In addition to soda-lime and lead glass, there are several speciality soft glasses in the laboratory. One of the more notable is Exax made by the Kimble Corporation. This glass repels a static charge, making it particularly useful for holding or weighing powders. 

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