CHAPTER XIV. HYDRIC CHLORIDE (HCI). (Hydrochloric Acid-Muriatic Acid-Spirits of Salts.) Molecular weight, 36.5. Molecular volume, = 18.25 sp. gr. Or 18 25 grammes of HCl measure 11.2 litres. 18.25 grains of HCI measure 444 cubic inches. 195 HYDRIC CHLORIDE. 294. What is the composition of hydrochloric acid by weight and by volume? July 1849-July 1855July 1857-Jan. 1861-July 1863—June 1864. By weight it is 1 of H and 35·5 of Cl. 295. What is the density of hydric chloride in the state of vapour? July 1855-Jan. 1861. Its density compared with hydrogen is its molecular weight, 36.5, or (1+35·5), divided by its volume, which is 2, and which is often represented by 296. Why is hydric chloride called by some chemists hydrochloric acid? June 1881. It is called by them an acid because it turns blue litmus red, and also precipitates the metals of the bases from their solutions. It is called chloric because it contains chlorine, and hydro- because it contains hydrogen; expressing at the same time that it is an hydracid to distinguish it from an oxacid. 297. State the composition of nitric, sulphuric, and hydrochloric acids. Describe the results observed when the metal copper is dissolved in the first-named of these acids, and when the metal zinc is dissolved in either of the two other acids named. July 1851. The composition of nitric acid (hydric nitrate) is 1 atom of H, 1 of N, and 3 of O (HNO3). The composition of sulphuric acid (hydric sulphate) is 2 atoms of H, 1 of S, 4 of O (H2SO1). The composition of hydrochloric acid (hydric chloride) is 1 atom of H and 1 of Cl (HCl). When copper is dissolved in hydric nitrate, red fumes are given off, and a blue liquid is formed, which crystallises by evaporation. When zinc is dissolved in hydric sulphate, hydrogen is evolved, and a solution of zincic sulphate remains, which may also be crystallised by evaporation. Finally, when zinc is dissolved in hydric chloride, there is formation of free hydrogen, also a solution of zincic chloride remaining. 298. How would you distinguish aqueous hydrochloric acid from an aqueous solution of nitric acid? Jan. 1869. Firstly. I should dip a piece of silver, or better still copper, into each liquid. Both solutions being diluted, the one containing hydric chloride would have no action upon the copper or upon the silver. On the contrary, when dipped into the bottle containing the hydric nitrate, heavy red fumes would at once be formed, and the liquid would become green or blue. Secondly. I should dip the horny portion of a quill into such solution. Dipped into that containing the hydric nitrate, the quill would become yellow, but not so when dipped into that containing the hydric chloride. Thirdly. I should pour a few drops of argenti nitrate into both vessels. That in which a white precipitate would be produced would be the solution of hydric chloride, and that in which no precipitate is formed would be the solution of hydric nitrate. 299. What are the tests of hydrochloric acid? July 1857. Argentic chloride produces a white precipitate when poured into a solution of hydric chloride, and hydric chloride when poured over common salt gives off dense white fumes and great heat. 300. What products are obtained on mixing nitric acid with hydrochloric acid? Jan. 1863. If hydric nitrate be mixed with hydric chloride in the proportion of 1: 3, then a liquid is formed which has the property of dissolving gold, whence it obtained the name of aqua regia,' gold being considered the king (rex) of metals by the alchemists. It is generally supposed that the real solvent in this case is chlorine in the nascent' state, resulting from the partial combination of one acid with the other. 301. What volume of hydrochloric acid gas is needed in order to condense a cubic inch of ammonia ? June 1868. Since hydric chloride and ammonia combine in equal volumes, it is clear that one cubic inch of hydric chloride will be needed to condense one cubic inch of ammonia. 302. It is asserted that one molecule of hydrochloric acid consists of one atom of chlorine and one |