E. I. Du Pont de Nemours reported a 47 percent surge in third-quarter earnings mainly due to its specialty products and plastics business.

Dow Chemical Co. and Monsanto Co. also reported increased third-quarter earnings yesterday.

Du Pont said it earned $208 million ($4.28 a share) in the latest period compared with $143.3 million ($2.91) a year earlier as sales increased from $2.36 billion to $2.63 billion.

Nine-month profits were $566.9 million ($11.65) on sales of $7.9 billion compared with earnings of $425.7 million ($8.64) a year earlier on sales of $7.1 billion.

Chairman Irving S. Shapiro noted that the results were contracyclical in that Du Pont earnings customarily drop in the third quarter from the June quarter but this year the company successfully resisted the summer slump. He said earnings from chemicals, plastics and the consumer specialty product sales were up 31 percent from a year ago and fiber sales were 11 percent higher.

Dow Chemical said its profits for the third quarter rose 6.1 percent on a sales gain of 5.4 percent. Earnings in the quarter were $153.4 million (85 cents a share), up from $144.5 million (78 cents) in the same 1977 quarter. Sales rose from $1.59 to $1.67 billion.

For the first nine months of the year, profits fell 3.1 percent from $451 million to $437 million as sales rose 8.3 percent from $4.68 billion to $507 billion. Earnings per share fell from $2.43 to $2.40.

Financial Vice President G. J. Williams said the third-quarter improvement reflected higher plant operating rates at home and abroad.

Monsanto had sales of $1.2 billion for the third quarter of 1978, an increase of 10 percent over sales in the same period a year ago. Net income was $46.8 million compared with $24.9 million for the same quarter in 1977, when the company recorded a series of write-offs and divestitures that penalized net income.

For the first nine months of 1978, sales were $3.7 billion compared with $3.5 billion for the same period a year ago. Earnings for the first nine months were $258.6 million compared with 254.3 billion for the first three quarters of 1977.

John W. Hanley, Monsanto chairman and president, attributed the improved sales and income to higher-than-expected export volume. "We were adversely affected, however, by operations outside the United States," he said. "Losses continued in certain of our manufacturing operations abroad."

Gulf & Western Industries Inc. had record earnings for the final quarter of 1978 and the second-highest annual earnings in the firm's history.

G&W attributed the sharp gain for both the quarter and year to "the unprecedented success" of its Paramount Pictures unit - whose productions included "Grease" and "Saturday Night Fever" - and to its financial services group and to its manufacturing, paper and building products group.

Fourt-quarter earnings were $57.6 million (84 cents a share), up from $23.1 million (43 cents) in the same period a year ago. The 1978 fourth-quarter figure includes a $20 million gain from commodity trading and hedging - primarily sugar - compared with a $5.1 million loss in similar operations a year ago. G&W said earnings also include a $21.4 million writedown from closing or sale of unprofitable or marginally profitable operations.

Fiscal 1978 earnings rose to $180.5 million ($2.66) from $150 million ($2.21) for the whole of 1977.

Sales for the fourth quarter were a record $1.21 billion compared with $922.34 million in the final quarter last year. For the year, sales were $4.3 billion, also a record, and up from $2.65 billion last year.

Polaroid Corp. posted record world-wide sales and earnings for both the third quarter and first nine months of 1978.

Sales increased by 34 percent in the last three months to $341.69 million from $242.22 million, President William J. McCune Jr. said.

He said both domestic and international operations produced record sales. He credited the SX-70 cameras and film with being "primarily responsible for the substantial third-quarter sales gain, with unit sales of SX-70 film about double those of the same period a year ago."

Sales during the first nine months of 1978 were $902 million, a 30 percent increase. From January to September last year, Polaroid sales hit $695.3 million.

Thus far this year, Polaroid has shown a net profit of $75.03 million ($2.28 a share), an increase of 38 percent over last year.

Inland Steel Co., reported record salese, raw steel production and shipments for the third quarter and nine-month period, but profits fell short of expectations.

Inland Chairman Frederick G. Jaicks said profits failed to reach peak levels at the nation's fifth largest steel product because of "the depressing effect of government pressures and subsidized imports on prices, and severe cost escalation caused by excessive government regulatory measures and inflation."

Third-quarter earnings were $40.3 million ($1.94 a share) more than double the $19.7 million (95 cents) reported for the same period last year.

Sales for the third quarter were a record $812.8 million, up 19 percent from the 1977 figure of $680.7 million. Sales for the nine-month period set a record at $2.407 billion, 20 percent above the corresponding 1977 results of $2.009 billion.

Nine month net income rose from $72.1 million (3.49) last year to $110.7 million ($5.33).

Braniff International reported record third-quarter net earnings of $15.04 million (75 cents a share), representing an 80.7 percent increase over the $3.32 million (42 cents) earned in the same period last year.

The third-quarter results brought Braniff's net earnings for the first nine months of the year to $35.1 million ($1.75). This was a record high and an increase of 42.1 percent over the first nine months of 1977, when Braniff earned $24.7 million ($1.24).

Braniff Chairman Harding L. Lawrence said the earnings, revenues and airline passenger traffic during the three months ended Sept. 30 were higher than in any other single quarter in the company's 50-year history.

Revenues rose from $200.3 million to $257 million in the third quarter and from $574.3 million to $711.2 million in the nine months.

Caterpillar Tractor Co. reported record third-quarter sales of $1.82 billion and profits of $139 million, both up 20 percent from the same period last year.

The last performance put 1978 sales of the Peoria-based earth-moving-equipment company at $5.29 billion, up 22 percent, and profits thus far this year at $408.8 million, an increase of 23 percent over 1977.

Third-quarter net income per share increased 28 percent to $1.62, a third-quarter record. For the first nine months, it was $4.74, up from $3.84 for the same period last year.

The company said the record sales and profits were offset partially by the effort of the weakeded U.S. dollar on the foreign money markets.

U.S. sales accounted for about 47 percent of the total for the first nine months of 1978, versus slightly more than 50 percent for the same period one year ago. U.S. sales were up 25.3 percent over 1977's third quarter, and foreign sales were up 14.7 percent, according to the company.

Wheeling Pittsburgh Steel Corp. announced sharp increases in third-quarter and nine-month earnings compared with the same periods in 1977, a lackluster year in the steel industry.

The nation's ninth largest steel producer said net income for the third quarter was $13.5 million ($3.40 a share) on sales of $304.3 million.

Last year, Wheeling-Pittsburgh reported a third-quarter loss of $4.5 million on sales of $253.3 million.

Shipments for the period were 761,003 tons compared with 698,818 tons in 1977.

For the first nine months, the company reported net income of $4 million (47 cents) on sales of $857.6 million. In 1977, Wheeling-Pittsburgh lost $20.6 million on sales of $26.8 million for the nine months.

Wheeling-Pittsburgh Chairman Dennis Carney said the third-quarter rebound "reflects moderate but inadequate price increases, a small increase in volume and the continuing momentum of corporate-wide cost reductions."

And Koppers Co. reported third-quarter net income of $25.3 million ($1 a share) compared with $23 million ($92 cents) in 1977. Third-quarter sales totaled $447.4 million, up from $369.5 million last year.

Net income for the ninth-month period was $49.5 million ($1.96) compared with $45.8 million ($1.83) in 1977. Sales for the ninth months totaled $1.13 billion compared with $973.2 million last year.