In the [fourth Research] the history of the respirability and extraordinary effects of nitrous oxide is given, with details of experiments on its powers made by different individuals.

I cannot close this introduction, without acknowledging my obligations to Dr. Beddoes. In the conception of many of the following experiments, I have been aided by his conversation and advice. They were executed in an Institution which owes its existence to his benevolent and philosophic exertions.

Dowry-Square, Hotwells, Bristol.
June 25th, 1800.

RESEARCH I.

concerning the analysis of
NITRIC ACID and NITROUS GAS

and the production of
NITROUS OXIDE.

Pl. I.
MERCURIAL AIRHOLDER and BREATHING MACHINE
.

Lowry sculpᵗ.

RESEARCH I.