Four of the nation's leading petroleum companies turned in mixed earnings reports yesterday, although profits generally were up for the third quarter.

Crediting increased revenues from refined products and natural gas, Shell Oil Co. reported earnings rose 19 percent for the third quarter.

Earnings were $248.8 million ($1.66 a share), compared with $208.7 million ($1.45) in the same period last year.

Revenues increased from $2.6 billion to $2.9 billion

For the nine months ending Sept. 30, earnings of $621 million ($4.18) compared with $567 million ($3.96) a year earlier. Revenue was $8.3 billion, up from $7.6 billion.

John F. Bookout, president, said the nine-months earnings, in addition to increased products and natural gas sales volumes and prices, also benefitted from reduced purchases of high-cost foreign crude oil.

Continental Oil Co. reported third-quarter net income yesterday of $105.8 million, an increase of 30.6 percent over restated 1977 earnings of $81 million. Net income for the nine months was $296.1 million, down 0.9 percent from restated earnings of $298.7 million last year.

Earnings per share were 98 cents, compared with 75 cents in 1977

Conoco Chairman Howard W. Blauvelt attributed the increase in third-quarter income to improvements in all the company's operations.

Phillips Petroleum Co., adversely affected by foreign currency fluctuations, reported third quarter net earnings of $107.8 million (70 cents a share), down from $12.2 million (80 cents) a year ago.

Nine-month earnings for Phillips were $411.1 million ($2.67), an increase over last year's $369.8 million ($2.41). The company reported revenue through the third quarter of $5.22 billion, compared to $4.71 billion last year at this time.

Marathon Oil Co.'s net income for the first nine months of 1978 was $151.3 million ($5.01 per share), up over 8 percent from the $139.8 million ($4.65) earned in the first nine months of 1977.

Third quarter earnings amounted to $50.5 million ;$1.67), an improvement of nearly 2 percent from teh $49.6 million ($1.65) earned in the comparable quarter last year.

Declines in liquid hydrocarbon production from third quarter 1977 rates in a number of fields were offset partially by a Sept. 1 increase in the allowed production of the Yates Field in Texas by 25,000 barrels a day.

Lockheed Corp., one of the country's largest aeropace concerns, yesterday reported sharply lower profits for the third quarter and nine months.

The company attributed the decline to a variety of factors, including continued losses connected with its £1011 Iristar commercial transport program, 14 fewer C130 Hercules deliveries, and substantially lower sales of the Viking S3A anti-submarine warfare aircraft to the government as a result of the phase-out of the program in August.

Lockheed's profits from operations in the quarter ended Sept. 30 fell to $9.1 million, (53 cents a share), from $21.9 million ($1.50) a year earlier. Sales rose to $852 million from $811 million.

For the nine months, profits declined to $32 million ($1.99) from $47 million ($3.22) in the year ago period. Sales slowed to $2.45 billion from $2.48 billion dollars.

A $12 million after-tax gain resulting from a settlement of litigation with International Busuness Maching Corp. raised Xerox Corp's third quarter profit to $1.67 a share from $1.31 a year earlier.

Operating earnigns in the quarter were $1.52 a share, up 16.5 percent from a year ago. Revenues were up 20 percent to $1.513 billion from $1.263 billion.

Nine months net income was $368 million ($4.57 a share) a revenues of $4.34 billion against $310.7 million ($3.87) a year earlier on revenues of $3.732 billion. Nine months operating profit was $4.42 a share.

Textron Corp's third-quarter results set a third-quarter record for sales and an all-time high in quarterly earnings, Charman Joseph B. Collinson said yesterday.

Net income for the quarter rose 19 percent over the same period last year on a 17 percent sales increase.

Earnings per share increased 18 percent to $1.11, from 94 cents last year. Net income rose to $42 million, from $35 million 1977.

American Broadcasting Corp., which has remained at the top of the television ratings, reported record third quarter earnigs yesterday.

Citing a strong performance in broadcasting and publishing operations, ABC reported earnings of $25.4 million (91 cents per share), up 14.4 percent from $22.2 million (81 cents) in the same period last year.

Revenues for the quarter ended Sept. 30 were $413.5 million, up from last year's third quarter figure of $357.0 million.

Earnings for the first nine months were $90.1 million ($3.26), up from the comparable year ago period of $75.0 million ($2.75). Two stock split, effective Sept. 19, 1978.

Eastern Airlines reported yesterday that its earnings soared to $20 million in the third quarter of 1978, assuring the firm of its most profitable year ever.

Frank Borman, Eastern chairman and president, also said the third-quarter profit was the highest for the period in the carrier's 50-year history. He attributed the rosy earnings picture to increased passenger volume and the popularity of discount fares.

Eastern said its third-quarter earnings rose to $20 million (93 cents per share), from $1.6 million (eight cents) for the dame period of 1977.

Revenue increased to $604.6 million for the quarter justed ended from $579.9 million for the comparable period last year. Borman said earnings for the first nine months of the year rose to $63.7 million ($2.99) from $20.1 million ($1.01) for the first nine months of 1977.

Nine-month revenue climbed to $1.79 billion from $1.51 billion last year.

Consolidated Edison Co. of New York, one of the largest operating utilities in the country, reported a decrease in third quarter earnings of three percent yesterday.

Earnings for the quarter ended Sept. 30 were $104.3 million ($1.51 per share), off from the year ago quarter of $107.9 million ($1.57). Revenue for the period were $800.7 million, down from last year's $830.1 million.

Nine months net income was $253.9 million ($3.57), down from the comparable year ago period of $264.0 million ($3.75).

TRW Inc., a conglomerate with interest in the automotive, aviation and machine parts fields, reported record third quarter earnings of $42.2 million ($1.31 per share), compared with $36.4 million ($1) a year ago.

Sales also rose to a record level of $927.9 million, up from $797.3 million in the third quarter of 1977.

Lukens Steel Co. reported yesterday that 1978 third quarter earnings were 45.9 percent ahead of the same period last year.

Lukens' earnings were $3.82 million (74 cents pre share) on sales of $91.87 million for the 16-week third quarter ending Oct. 7 . Comparatively, earnings for the 1977 third quarter were $2.62 million (51 cents) on sales of $81.34 million.