He was particularly unhappy about the lack of information about the fraction of air (the majority) which was not oxygen.
That means that the play was without fail written after (in Latin, post) 1587.
This usually requires what is commonly known as a "dating method".
Several dating methods exist, depending on different criteria and techniques, and some very well known examples of disciplines using such techniques are, for example, history, archaeology, geology, paleontology, astronomy and even forensic science, since in the latter it is sometimes necessary to investigate the moment in the past in which the death of a cadaver occurred.
Carbon 14 is continually being created in the Earth's atmosphere by the interaction of nitrogen and gamma rays from outer space.
Since atmospheric carbon 14 arises at about the same rate that the atom decays, the Earth's levels of carbon 14 have remained constant.
Cavendish used an electric spark in air to react the oxygen and nitrogen to form nitrogen oxides.