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7 HE ALUMNI JOURNAL. 



THE MANUFACTURE OF CHLORINE.^ 



By Dr, LuDWiG Mond, f.r.s. 



The early history of chlorine is par- 

 ticularly interesting, as it played a most 

 important role in the development of 

 chemical theories. There can be no 

 doubt that the Arabian alchemist Geber, 

 who lived eleven hundred years ago, 

 must have known that "Aqua Regia," 

 which he prepared by distilling a mix- 

 ture of salt, nitre, and vitrol. gave off, 

 on heating, very corrosive, evil-smelling, 

 greenish-yellow fumes, and all his fol- 

 lowers throughout a thousand years must 

 have been more or less molested by these 

 fumes whenever they used Aqua Regia, 

 the one solvent of the gold they attempt- 

 ed so persistently to produce. 



But it was not until 1774 that the great 

 Swedish chemist Scheele succeeded in 

 establishing the character of these fumes. 

 He discovered that on heating mangan- 

 ese with muriatic acid he obtained fumes 

 very similar to those given off by "Aqua 

 Regia," and found that these fumes con- 

 stituted a permanent gas of yellowish- 

 green color, very pungent odor, very 

 corrosive, very irritating to the respira- 

 tory organs, and which had the power 

 of destroying organic coloring matters. 



According to the views prevalent at 

 the time, Scheele considered that the 

 manganese had removed phlogiston from 

 the muriatic acid, and he consequently 

 called the gas dephlogisticaced muriatic 

 acid. 



When, during the next decade, Lavoi- 

 sier successfully attacked, and after a 

 memorable struggle completely upset 

 the phlogiston theory, and laid the foun- 

 dations of our modern chemistry, Ber- 

 thollet, the eminent "father" of physical 

 chemistry — the science of to-day — en- 

 deavored to determine the place of 

 Scheele' s gas in the new theory. Lavoi- 



President's Address at the chemistry section of the 

 British Association for the advancement of science. 



sier was of opinion that all acids, includ- 

 ing muriatic acid, contain oxygen. Ber- 

 thollet found that a solution of Scheele' s 

 gas in water, when exposed to the sun- 

 light, gives off oxygen and leaves behind 

 muriatic acid. He considered this as 

 proof that this gas consists of muriatic 

 acid and oxygen, and called it oxygen- 

 ated muriatic acid. 



In the year 1587 Berthollet conceived 

 the idea of utilizing the color-destroying 

 powers of this gas for bleaching purpos- 

 es. He prepared the gas by heating a 

 mixture of salt, manganese and vitrol. 

 He used a solution of the gas in water 

 for bleaching, and subsequently dis- 

 covered that the product obtained by ab- 

 sorbing the gas in a solution of caustic 

 potash possessed great advantages in 

 practice. 



This solution was prepared as early as 

 1789, at the chemical works on the Quai 

 de Javelle, in Paris, and is still made 

 and used there under the name of "Eau 

 de Javelle." 



James Watt, whose great mind was 

 not entirely taken up with that greatest 

 of all inventions — his steam engine — by 

 which he has benefited the human race 

 more than any other man, but who also 

 did excellent work in chemistry— became 

 acquainted in Paris with Berthollet's 

 process, and brought it to Scotland. 

 Here it was taken up with that energy 

 characteristic of the Scotch, and a great 

 stride forward was made, when in 1798, 

 Chas. Tennant, the founder of the great 

 firm, which has only recently lapsed into 

 the United Alkali Company, began to use 

 milk of lime in place of the more costly 

 caustic potash, in making a bleaching 

 liquid; and a still greater advance was 

 made when, in the following year, Ten- 

 nant proposed to absorb the chlorine by 

 hydrate of lime, and thus to produce a 

 dry substance, since known under the 



