Glasses containing metal nanoparticles are very promising materials for photonics applications due to their unique linear and nonlinear optical properties. In this letter, it is shown that silver nanoparticles within a glass matrix can be destroyed and dissolved in the glass in the form of silver ions by applying a combination of an intense direct current (dc) electric field and moderately elevated temperature. The nanoscopic processes leading to this unexpected effect are discussed, and it is demonstrated that this technique allows us to produce optical structures down to the submicron scale, making it suitable for the design of various optical and optoelectronic elements.