Patrons of the National Symphony Orchestra! Fear not the young composer who writes electronica as well as classical, comes clad in a black collarless shirt with a pink racing stripe down the side, and sits brandishing a laptop and dropping strange noises into and around the orchestral texture!

Mason Bates, 30 years old, raised in Virginia and a student of John Corigliano, knows how to command an orchestra just as well as he does his touchpad. Bates's "Liquid Interface," an NSO commission that received its world premiere last night, surpassed in sheer sonic beauty even the works by Mendelssohn and Tchaikovsky that rounded out the program.

As described the composer's excellent program note, "Liquid Interface" follows water through various manifestations of its solid, liquid and gaseous phases: Glaciers calve, droplets stream and scurry, and a storm brews and crests before dissolving into a lakeside idyll reminiscent of Berlin's Wannsee. Using a truly gigantic orchestra -- the program listed a huge battery of woodwinds and 17 types of percussion, not counting the laptop -- Bates renders these scenes primarily with tone colors: humid clouds of strings tinged with brass, rising from the calved glaciers; a sprawling spray of pointillist squiggles for the droplets; and a glorious haze coming from the Wannsee that felt unreal in the best sense.

The thunks and blips from Bates's laptop served to add yet more color; the trip-hop beat that arose in the glacial section could barely be heard, but its distant scratch lent the music a welcome earthiness.

Sometimes, Bates's lack of interest in other musical materials -- neutral harmonies and abortive melodic fragments served mostly as a coloristic canvas -- undermined him. In the "Crescent City" movement, which attempts to evoke New Orleans, Bates recalled a Dixieland band with such vagueness that the evocation was barely recognizable; the run-up to the climax felt like a tension-free series of piquant sounds. But the sounds Bates created always held one's interest. The NSO vividly conjured Bates's vision, and Music Director Leonard Slatkin ensured a seamless collaboration between the composer and the rest of the orchestra.

Violinist Janine Jansen disappointed in Mendelssohn's Violin Concerto in E Minor, which followed the Bates. She tried to whip up a romantic storm out of the first movement, pushing around the melodies and brandishing her fine technique, but missed the geniality and sweetness of the music. When she played loudly and with vibrato, which was often, her violin produced a strident tone. She showed an ability to charm when playing more softly and more slowly, especially in the slow movement, and the quicksilver finale found her letting loose a bit more, to exciting effect, but she still missed Mendelssohn's wit. Slatkin and the NSO were (understandably) a little distant in their support.

In Tchaikovsky's Symphony No. 6, the "Pathetique," Slatkin drew fiery playing from the orchestra, sometimes too much so. This performance blasted past the undercurrents of irony in the second movement's wrong-footed waltz and the third movement's overzealous march. But the gripping first movement coiled with tension before slipping into the big clarinet tune (played with exceptional poise here by Loren Kitt), and the depiction of death in the finale received a performance so shattering that it was hard to remember to clap at the end.

The program will be repeated today at 1:30 p.m. and tomorrow at 8 p.m.