With his body covered with water and glycerine to make him look sweaty and sick, and oatweal to simulate motion sickness. LaVar Burton was so emotionally wrought during the filming of the scenes in the slave ship hold that "I could do nothing but grit my teeth and hold on."

These are the kind of emotions that ABC is hoping will be transferred to an estimated 70 to 80 million viewers when it presents the television adaptation of "Roots," Alex Haley's best-selling book, for eight consecutive evenings starting Jan. 23.

At the usually staid National Archieves, where Haley started to research the monumental history of his familu more than 12 years ago. ABC sponsored a reception and special preview last night of the first two hours of "Roots."

"Where is Alex Haley?" asked Senator edward Brooke (R-Mass.) as he bounded into the crowded reception room. "The book, the film and all the other results are going to do a lot for black history and culture," said Brooke. "I've learned a lot myself already."

The screening and the appearance of stars Burton and ben Vereen seemed to have more attraction for some congressmen than President Ford's State of the Union address. Brooke wrinkled his nose and shook his head in a negative gesture when asked if he was going back to Capitol Hill. Representative William Clay (D-Mo.) said "Roots" was far more impressive than Ford's message.

In the audience were many representativess of ABC, including Fred Pierce, the president of the ABC-TV network, who said he hoped the series would help "to explain a time in history that has had a tremendous influence on our social mores in the country today." "Roots" was produced for ABC by documentary king David Wolper. Neither Wolper nor actress Cicely Tyson, who has a dominant role in the first two hours, was able to attend last noght's reception because of illness.

Among the special guests was a nine-member contingent from The Gambia, the coastal African country where Haley found proof of his ancestry in the village of Juffure. A kora player for Gambia entertained during th ereception that followed the screening, and it was announced that Juffure has been designated a national monument because of the significance of "Roots" and the excitment it has generated.

Haley, who has written a mini-biography of President-elect Jimmy Carter for a post-inaugural booklet, said one of the most difficult passages to write in "Roots," which has been on the best-seller list for 14 weeks, was the slave-ship crowwing.He spent several night s in a cargo ship to assimilate the mood of those voyages. "But at times whole writing I just had to stop it was so unbearable," said Haley.

Burton, a 19-year-old drama student who plays Kunta Kinte, Haley's ancestor who is abducted by the slave-cathchers, said his experience on "Roots" had intensified his racial pride. "For every black man and woman in America there is a Kunta, an ancestor who survived the middle passage, but to tell the truth I didn-t know what the results of the scenes were until I saw it on the screen. I was just too overcome. It was helified."