Edison's wife, Mary, died on August 9, 1884, possibly from a brain tumor. Edison remarried to Mina Miller on February 24, 1886, and, with his wife, moved into a large mansion named Glenmont in West Orange, New Jersey. Edison's children from his first marriage were distanced from their father's new life, as Edison and Mina had their own family: Madeleine, born on 1888; Charles on 1890; and Theodore on 1898. Unlike Mary, who was sickly and often remained at home, and was also deferential to her husband's wishes, Mina was an active woman, devoting much time to community groups, social functions, and charities, as well as trying to improve her husband's often careless personal habits.

In 1887, Edison had built a new, larger laboratory in West Orange, New Jersey. The facility included a machine shop, phonograph and photograph departments, a library, and ancillary buildings for metallurgy, chemistry, woodworking, and galvanometer testings.
While Edison had neglected further work on the phonograph, others had moved forward to improve it. In particular, Chichester Bell and Charles Sumner Tainter developed an improved machine that used a wax cylinder and a floating stylus, which they called a graphophone. They sent representatives to Edison to discuss a possible partnership on the machine, but Edison refused to collaborate with them, feeling that the phonograph was his invention alone. With this competition, Edison was stirred into action and resumed his work on the phonograph in 1887. Edison eventually adopted methods similar to Bell and Tainter's in his own phonograph.
The lamp of Edison
The phonograph was initially marketed as a business dictation machine. Entrepreneur Jesse H. Lippincott acquired control of most of the phonograph companies, including Edison's, and set up the North American Phonograph Co. in 1888. The business did not prove profitable, and when Lippincott fell ill, Edison took over the management. In 1894, the North American Phonograph Co. went into bankruptcy, a move which allowed Edison to buy back the rights to his invention. In 1896, Edison started the National Phonograph Co. with the intent of making phonographs for home amusement. Over the years, Edison made improvements to the phonograph and to the cylinders which were played on them, the early ones being made of wax. Edison introduced an unbreakable cylinder record, named the Blue Amberol, at roughly the same time he entered the disc phonograph market in 1912. The introduction of an Edison disc was in reaction to the overwhelming popularity of discs on the market in contrast to cylinders. Touted as being superior to the competition's records, the Edison discs were designed to be played only on Edison phonographs, and were cut laterally as opposed to vertically. The success of the Edison phonograph business, though, was always hampered by the company's reputation of choosing lower-quality recording acts. In the 1920s, competition from radio caused business to sour, and the Edison disc business ceased production in 1929.
Other Ventures: Ore-milling and Cement
Another Edison interest was an ore-milling process that would extract various metals from ore. In 1881, he formed the Edison Ore-Milling Co., but the venture proved fruitless as there was no market for it. In 1887, he returned to the project, thinking that his process could help the mostly depleted Eastern mines compete with the Western ones. In 1889, the New Jersey and Pennsylvania Concentrating Works was formed, and Edison became absorbed by its operations and began to spend much time away from home at the mines in Ogdensburg, New Jersey. Although he invested much money and time into this project, it proved unsuccessful when the market went down and additional sources of ore in the Midwest were found.
Edison also became involved in promoting the use of cement and formed the Edison Portland Cement Co. in 1899. He tried to promote widespread use of cement for the construction of low-cost homes and envisioned alternative uses for concrete in the manufacture of phonographs, furniture, refrigerators, and pianos. Unfortunately, Edison was ahead of his time with these ideas, as widespread use of concrete proved economically unfeasible at that time.