It's still summer and you're sitting under the sycamore in the back yard, staring at that Potomac sun and wishing you had something good to drink. Something good would be cool, fresh, effervescent and--ideally--would carry you through supper. Most people in these circumstances settle for a spritzer, that gustatory nonentity that combines white or red wine with soda, and is neither wine nor water.

The obvious alternative is, of course, champagne: delicious, class sparkling wines, vins mousseux, are also out of the financial range of most casual diners, as are the palatable alternatives from California. In the last few years Spanish producers have moved strongly into the breach created by a willing audience and finite means. Cheap labor, a tradition of well-made sparkling wines in Spain, and determined marketing have made some good Spanish exuberance available at tolerable prices. Drink them as aperitifs, before or after dinner, or with dessert, in narrow glasses that conserve the bubbles, never in one of those saucer-shaped "champagne" glasses. A few are pleasant company with an entire meal, though finding out which ones can muddy a lot of good fish and summer squash.

In France, "champagne" must come from a designated area in the north, near Reims. The United States is the only country where the term "champagne" is appropriated for sparkling wine. In Spain it is called xampan, but you're not likely to find that word on the label. Instead, you'll see the phrase, "m,ethode champenoise," meaning it is not bulk-produced and fermented in the bottle, part of the laborious, costly attention that makes champagne so expensive. Fortunately sparkling wines travel well, being mostly immune to the reverberations of Atlantic voyages.

Whether or not Catalonian hands actually turned these bottles a hundred times, deftly bleeding off the residue, I can't say. The wines have none of the yeasty quality of bulk sparkling wine, but some are a bit sour on the second or third sip, which in such a case is time to stop. The wines with recognizable names are not necessarily the best. For instance, large cellars in San Sadurn,i de Noya belonged to the famous Codorn,iu, but the wine with that name, at $5, is flat and unappealing.

I found two good, and one exceptional, wines for about $6 each. The most popular, Freixenet Cordon Negro, in the sleek black bottle, is also the most expensive we tasted, at $6.50. It had what the the vintner calls "a good bubble," but a steely aftertaste that grew more pronounced. I prefered Perelada's Brut Castillo, at $6, softer, lighter and more consistently pleasing, though less effervescent. Neither wine made it through the meal with any distinction.

Not so Paul Cheneau. Straw-colored, inexpensive, effusive, this sparkling wine comes in a champagne-like bottle with a formidable cork and an airy, more Frenchified label. The man, Paul Cheneau, does not exist, but don't let that worry you. The Spanish producers decided that it was the best name for an American audience, and fortunately put behind it a product that is resourceful, with a pleasant aftertaste. We drank it happily with cold sliced chicken breast stuffed with spinach and feta cheese, and sliced tomatoes.

All three wines can be found at Woodley-Calvert Liquors, Pearson's and several other stores. Any of the three xampans will provide a sparkling antidote to the heat and the deflating reality of summer's end.