PROVIDENCE -- The state attacked some of the defenses voiced by the lead-paint industry yesterday by presenting a chemistry professor who testified that he believes lead-based paints can always be expected to deteriorate and there were just as good alternative pigments that would not poison children.

Prof. James Girard, chairman of the chemistry department at American University, was the second witness in the state's nuisance suit against four corporations that sold lead-based pigments that continue to poison children.

On cross-examination, however, a defense lawyer, Donald Scott, quickly tried to diminish Girard's credibility by questioning his lack of experience in working with lead paints and the sizable income he makes by testifying at other trials against the manufacturers.

"Is it accurate to say, Dr. Girard, that you spend roughly 25 percent of your time as an expert witness in litigation?" asked Scott.

"I think so," Girard responded.

"Do you make 50 percent of your income that way?" Scott asked.

"I do," Girard said.

No actual dollar figures about Girard's income were brought out.

But under questioning from Scott, Girard testified that he had never formulated lead paint, he had no training in paint chemistry and he had never done any research into how paint deteriorates until he was hired to be an expert witness for the state of Rhode Island.

Girard testified that he has written several books on chemistry, including a college textbook and a more simplified text for non-science majors.

He said plumbers got their name from the Latin word for lead, because years ago plumbers used a lot of lead in pipes and fittings. Plumbers were essentially lead workers.

Girard cited an article in Good Housekeeping magazine in 1915 by Harvey W. Wiley, the country's chief chemist (a predecessor of the Food and Drug Administration), who wrote that people should paint their interior walls so they can be readily cleaned. And, Wiley wrote, people should use zinc-based pigments because, unlike lead, they are nontoxic.

"My opinion is there were fine pigments that were non-leaded and they were certainly as competitive as leaded pigments," Girard said. "One lead formula might be a bit more durable than others. But other manufacturers had non-lead pigments that were equally as durable."

Girard also cited industry documents that asserted that lead-based paints have a tendency to crumble and chalk.

"It is my opinion that all paint fails," Girard said. "It is just a matter of when it fails."

Before the trial resumed yesterday, court officials reported that one of the six alternate jurors selected for the trial had called in sick. After meeting with lawyers for the state and the defense, Judge Michael A. Silverstein excused the juror and decided to continue with the six-person jury and five alternates.