Note 29 — HISTORICAL INTRODUCTION.
Reading edition
See Phil. Trans., Part II., 1861, pp. 444-446. Lawes & Gilbert. Schloesing has found in the air in the neighbourhood of Paris 1 lb. of ammonia in 26,000,000 cubic yards; while Müntz found only about half that amount in a similar quantity of air on the top of the Pic du Midi.