As the music industry searches for a genre to fill the sales void left by alternative rock's commercial decline, rap and R&B are delivering a welcome string of hits: Combined sales of the genres rose by 18 percent between January and June, according to SoundScan. From the look of this weeks album sales chart, that trend is picking up steam in the second half of 1997. For the week ending August 3, Bone Thugs-N-Harmony's "The Art of War" debuts at No. 1, ousting Puff Daddy's "No Way Out," which last week bumped the R&B-oriented "Men in Black" soundtrack from the top spot. That's a lot of beats at the top of the chart.

\\"The Art of War" sold 394,000 copies for the week ending August 3, followed by "No Way Out" (301,000); "Men In Black" (166,000); the Spice Girls\rquote "Spice" (133,000); Hanson's "Middle of Nowhere" (116,000); Sarah McLachlan\rquote s "Surfacing" (105,000); the electronica-meets-heavy-metal soundtrack to "Spawn" (98,000); Prodigy\rquote s "The Fat of the Land" (91,000); Matchbox 20\rquote s "Yourself or Someone Like You" (85,000); and Jewel\rquote s "Pieces of You" (82,000).

\\One of the week's two other top 20 debuts also went to an R&B album -- Joe's "All That I Am," which enters the chart at No. 13. The other went to Pantera's "Official Live" at No. 15. The ot