FROM BICARBONATE TO STRONG ION DIFFERENCE- INTRIGUING STORY OF BLOOD ACID-BASE ANALYSIS “Life is struggle, not against sin, not against money power…. but against Hydrogen ion.” - H.L. Mencken, 1919 Since the understanding of similarity between fermentation of wine and respiration of animals, evolution of human physiology and measurement of carbon dioxide is coupled with studies of acids and bases. Alkalinity of blood was demonstrated by color indicators as early as eighteenth century by French chemist Hilaire Marin Rouelle, and one century later, its relation with gastric acid secretion was recognized by Henry Bence Jones. In 1831, William B. O’Shaughnessy, an Irish physician working in India, demonstrated that Cholera reduced the free alkali of blood. But the discovery of relationship between blood alkalinity and carbon dioxide was contained within the mystery of diabetic coma. 1. Story of Carbon Dioxide and Alkalinity of blood In Nineteenth century clinicians were intrigu