HCl ........Hydrochloric (in gastric juice) HNO₃ .......Nitric H₂SO₄ ......Sulfuric C₂H₄O₂ .....Acetic (vinegar) C₆H₈O₇ .....Citric (lemon juice) BASES NaOH ......Sodium hydroxid (caustic soda) KOH .......Potassium hydroxid (caustic potash) Ca(OH)₂ ...Calcium hydroxid (slaked lime) NH₄OH .....Ammonium hydroxid (Ammonia gas dissolved in water produces this alkali.) The equation for this is as follows: NH₃ + H₂O + NH₄OH (Ammonia) gas + Water + Ammonium hydroxid SALTS NaCl .......Sodium chlorid (table salt) KNO₃ .......Potassium nitrate (salt-peter) CuSO₄ ......Copper sulfate (blue vitriol) Ca₃(PO₄)₂ ..Calcium phosphate (normal) (The mineral of bones) [Sidenote: Formation of salts in the human body] FLUORIN, BROMIN, IODIN--These three elements are in many respects like chlorin. The first is a gas, the second a heavy, reddish-brown liquid at ordinary temperature, and the third a dark, grayish crystalline solid. These elements all form acids just as chlorin forms hydrochloric acid. These acids produce salts, and these various salts exist in small quantities in the human body. MINERAL SULFUR--This element is of no particular importance or use to the body, as it is insoluble and cannot be digested. The compounds of sulfur, however, are numerous and important. Sulfuric acid, sometimes called oil of vitriol, is one of the most active chemicals known, and is especially destructive to living tissue, as it combines with the water in the tissue so rapidly as to char or burn it. When sulfur is burned in air it forms sulfur dioxid, SO₂, which is used for the purpose of fumigation or destroying alleged dis-ease germs. This SO₂ dissolved in water gives H₂SO₃, sulfurous acid. By oxidizing this another part of oxygen is added, forming H₂SO₄. All three of these compounds are poisonous and harmful. HYDROGEN SULFID, H₂S, is a poisonous gas with a bad odor. It is formed by the decay of certain food substances, such as eggs. Sometimes this gas occurs in intestinal fermentation. CARBON DISULFID, CS₂, is used extensively to kill insects. The salts of sulfuric acid, or sulfates, are quite important, and many of them are poisonous. Glauber's salt (sodium sulfate Na₂SO₄) and Epsom salts (magnesium sulfate MgSO₄) are extensively used by the medical profession as purgatives. These poisons cause the intestines to act violently in an effort to throw out the offending substances. VEGETABLE SULFUR IN THE HUMAN BODY--I have herein mentioned a number of sulfur compounds which are foreign or harmful to animal life. In wonderful contrast to this is the fact that sulfur is an essential constituent of the human body, and in certain complex compounds with nitrogen and other elements, forms the brain, nerves, and many other body-tissues.