It differs from the simple ketenes in that it is apparently unacted upon by phenols and alcohols.
Wohler reduced the sesquioxide by zinc, and obtained a shining green powder of specific gravity 6.81, which tarnished in air and dissolved in hydrochloric acid and warm dilute sulphuric acid, but was unacted upon by concentrated nitric acid.
In the massive state it is unacted upon by dry air, but if moistened with acidified water, oxidation takes place slowly.
It is a volatile compound which burns when heated in oxygen and which is unacted upon by sulphuric and hydrochloric acids.