PART III.--POISONOUS GASES: CARBON MONOXIDE--CHLORINE--HYDRIC SULPHIDE. I. CARBON MONOXIDE. 37. Properties of Carbon Monoxide, 64 38. Symptoms--Acute Form--Chronic Form, 64-66 39. Poisonous Action on the Blood--Action on the Nervous System, 66, 67 40. _Post-mortem_ Appearances, 67 41. Mass Poisonings by Carbon Monoxide--The Leeds Case--The Darlaston Cases, 67-70 42. Detection of Carbon Monoxide--The Cuprous Chloride Method-- Wanklyn’s Method--Hempel’s Method, 70, 71 II. CHLORINE. 43. Chlorine; its Properties--The Weldon Process of manufacturing “Bleaching Powder,” 71, 72 44. Effects of Chlorine, 72 45. _Post-mortem_ Appearances, 72 46. Detection of Free Chlorine, 72 III. HYDRIC SULPHIDE (SULPHURETTED HYDROGEN). 47. Properties of Hydric Sulphide, 72, 73 48. Effects of breathing Hydric Sulphide--Action on the Blood--The Cleator Moor Case, 73, 74 49. _Post-mortem_ Appearances, 74 50. Detection, 74 PART IV.--ACIDS AND ALKALIES. SULPHURIC ACID--HYDROCHLORIC ACID--NITRIC ACID--ACETIC ACID--AMMONIA --POTASH--SODA--NEUTRAL SODIUM, POTASSIUM, AND AMMONIUM SALTS. I. SULPHURIC ACID.