At the same time, many other workers reported negative results.[12][13] One of the pioneer experiments was that of Bach in 1893,[14] who observed the formation of lower uranium oxides upon irradiation of a solution of uranium acetate and carbon dioxide, implying the formation of formaldehyde. Some experiments included reducing agents such as hydrogen gas,[15] and others detected formaldeyhde or other products in the absence of any additives,[16][7] although the possibility was admitted that reducing power may have been produced from the decomposition of water during the experiment.[16] In addition to the main focus on synthesis of formaldehyde and simple sugars, other light-assisted reactions were occasionally reported, such as the decomposition of formaldehyde and subsequent release of methane, or the formation of formamide from carbon monoxide and ammonia.[15]