http://www.elmergates.com/mind_and_brain/art_of_mind-bulding.pdf
pp. 11
In 1879 I published a report of experiments showing that, when
the breath of a patient was passed through a tube cooled with ice so
as to condense the volatile qualities of the respiration, the iodide of
rhodopsin, mingled with these condensed products, produced no
observable precipitate. But, within five minutes after the patient
became angry, there appeared a brownish precipitate, which
indicates the presence of a chemical. compound produced by the
emotion. This compound, extracted and administered to men and
animals, caused stimulation and excitement. Extreme sorrow, such
as mourning for the loss of a child recently deceased, produced a
gray precipitate; remorse, a pink precipitate, etc. My experiments
show that irascible, malevolent, and depressing emotions generate
in the system injurious compounds, some of which are extremely
poisonous; also, that agreeable, happy emotions generate chemical
compounds of nutritious value, which stimulate the cells to
manufacture energy.