| 摘要 |
The arc-quenching tube described in the parent Specification is modified by the addition of magnesium or other metal peroxide to the polymerized derivative of acrylic acid or homologue thereof, together with, if desired, carbamide resin or oxamide. Suitable proportions by weight are 5-10 per cent of peroxide and 40-60 per cent of carbamide resin or oxamide. A suitable derivative is a mixture of polymerized esters of acrylic acid and polymerised acrylic acid nitrile, the filling comprising urea or thiourea formaldehyde resin, methylene urea, or oxamide. |
