Union Carbide Corp. had a 19 percent gain in profits for the final quarter of 1978 to $128.5 million ($1.98 a share) from $107.6 million ($1.67) a year earlier.

Sales rose to $2.09 billion from $1.82 billion. In the 1978 quarter, Carbide had a nonrecurring gain of 38 cents a share on the sale of its interest in a European petrochemical complex.

Profits for the year were $394.9 million ($6.10) on sales of $7.87 billion compared with $385.1 million ($6.05) on about 1.1 million fewer shares and sales of $7.04 billion in 1977.

Foreign currency translation losses were 91 cents a share compared with a loss of 42 cents a share from this source in 1977, but the actual charge against net income was only 4 cents a share because accounting rules require such charges to be accrued only when the currencies are actually converted, even it they are calculated sooner.

International sales were up 13 percent and domestic sales 11 percent for the year.

Xerox Corp. announced higher earnings for the fourth quarter and year, attributing the gains to increases in most areas of the company's business.

Fourth-quarter earnings were $108.9 million ($1.35 a share), up from $93.3 million ($1.16) last year. Revenues were $1.56 billion compared with $1.35 billion a year ago.

For all of 1978, Xerox siad earnings were $476.9 million ($5.92), up from$404 million ($5.03). The 1978 figures were increased by a $12 million extraordinary gain in the third quarter, the result of settlement of a lawsuit against IBM.

Annual sales for Xerox were $5.9 billion in 1978, up from $5.08 billion a year earlier.

Eastern Airlines, boosted by record-breaking volume on most of its routes, reported 1978 earnings that were the highest in its 50-year history and nearly double the figure for last year.

The record earnings came despite fourth-quarter results that were sharply lower than 1977's. The firm attributed the drop to reduced payments from the U.S. government for carrying mail.

Eastern reported 1978 earnings of $67.3 million ($2.91 a share) compared with $27.9 million ($1.38) the previous year. Eastern's best previous year was 1976, when it earned $39.1 million.

Revenues in 1978 were $2.38 billion versus $2.04 billion in 1977.

Company officials attributed the earnings surge to increased volume on company routes, the most lucrative of which are the Northeast-to-Florida runs. Eastern carried 37.4 million passengers last year, an increase of 6.1 million over 1977.

Eastern has criticized government efforts to stimulate competition and cur rates, but has benefitted by the results which included higher percentages of filled seats on many aircraft.

Fourth-quarter 1978 earnings were $3.5 million (9 cents) compared with $7.8 million (37 cents) in 1977. The firm said the difference was that Eastern received retroactive payments in 1977 of $11.4 million for carrying mail compared with $2.2 million in 1978.

The 3M Co. reported record fourth-quarter and yearly earnings for 1978, with annual earnings up 36.3 percent over the previous year.

Yearly net income of Minnesota Mining & Manufacturing Co. totaled $563 million ($4.83 a share) compared with $412.9 million ($3.57) in 1977.

Worldwide sales for the year rose 17.1 percent to $4.7 billion from $4 billion in 1977.

Fourth-quarter, net income totaled $147.2 million ($1.26) compared with $108.9 million (94 cents) in the final quarter of 1977. Fourth-quarter sales totaled $1.2 billion, up from $1 billion during the final quarter of 1977.

"Our results for 1978 reflect continued good growth in unit sales," said Raymond H. Herzog, board chairman and chief executive officer. Both domestic and international operations made significant contributions to the growth in sales and earnings, as did each of the nine major products groups, Herzog said.

Armco Inc. recorded a 66 percent earnings gain in 1978 and faces the coming year "in robust financial health," Armco Chairman Willian Verity said yesterday.

The firm earned $198.3 million ($4.29 a share) in 1978, according to preliminary results, compared with 1977 earnings of $119.71 million ($2.53). Sales in 1978 hit a record $4.36 billion, a 23 percent increase over sales of $3.55 billion in 1977.

No preliminary fourth-quarter results were released.

"Backlogs are extremely high in our key businesses, and orders continued at a favorable rat," Verity said."While there may be some fall-off in the national economic picture during the second half of the year, we see it as more blip than dip for our lines of business, with the economy strengthening in 1980," he said.

Verity noted record performances by Armco's petroleum equipment, machinery and service businesses, coupled with improvement in flat-rolled carbon and specialty steels.

Consolidated Edision Co. of New York reported an earnings drop in December, the quarter and full year. The utility firm boosted he quarterly dividend, however.

The company said earnings for the final quarter came to $55.71 million (72 cents a share) against $59.58 million (78 cents) a year earlier. Operating revenues eased to $707.59 million from $713.09 million.

For 1978, the company earned $309.56 million ($4.29) against $323.57 million ($4.53) for 1977. Revenues came to $3.01 billion compared to $3.02 billion the previous year.

Directors approved a 6-cent boost in the quarterly dividend to 61 cents a share payable March 15 to holders of record Feb. 7.

Two major computer manufacturers, Control Data Corp. and Sperry Rand Corp., reported increased earnings.

Control Data reported consolidated 1978 earnings of $89.5 million, a 42 percent increase over 1977 earnings of $63 million. Earnings per share increased from $3.65 to $5.17 for the year ended Dec. 31.

Control Data officials said the company's computer business and financial services subsidiary, Commercial Credit Co., contributed to the increase.

Revenues rose 19 percent in 1978 to $2.7 billion from last year's $2.3 billion.

For the nine months ended Dec. 31, Sperry Rand reported net income of $154.6 million ($4.39 a share) compared with $117 million ($3.37) for the 1977 nine months. Revenues were $2.994 billion, compared with $2.578 billion in the 1977 nine months.

J. Paul Lyet, chairman and chief executive, said "We had broad continuing new-order strength in the quarter, and strong revenue gains were recorded in our computer, farm equipment, fluid power and guidance and control businesses."

Fourth-quarter earnings at Control Data were $24.2 million ($1.40) compared with $14.7 million (85 cents) in the final quarter of 1977. Revenues were $769 million compared with $650 million in the same quarter of 1977.

Sperry Rand's net income for the third quarter was $57.13 million ($1.62) compared with $39.6 million in the same period of 1977. Revenues rose from $906.1 million in the 1977 quarter to $1.04 billion in the 1978 third quarter.