A HISTORY OF THE SODA MANUFACTURE. 249 



The whole art of the extraction of soda from common salt having 

 been made patent to the French community by its publication, in 1797, 

 in the Annales de Cliimie, it would appear extraordinary that so many 

 years should have elapsed before these processes were adopted in our 

 own country. This was probably occasioned, in the first instance by 

 the war then raging, which cut off nearly all communication between the 

 two countries ; but a still greater obstacle existed (also a consequence of 

 the war), namely, the duty of 30Z. per ton on salt, and this continued to 

 exist until 1823, eight years after the restoration of peace. 



In the latter part of the last century — viz., 1774, the Swedish che- 

 mist, Scheele, was the discoverer of chlorine (then called oxy-muriatic 

 acid) ; also of its property to destroy vegetable colours, and this property 

 was studied by the French chemists, Lavoisier and Berthollet, who 

 succeeded in founding upon it a successful process for bleaching 

 linens. 



This process was brought over to Scotland in 1787 by Professor 

 Copeland, of Marischal College, Aberdeen, who communicated it to 

 Messsrs. Gordon, Barron, & Co., bleachers, of Aberdeen, and these 

 gentlemen applied the process successfully as a practical operation for 

 bleaching calicoes. In the following year, a large bleaching establish- 

 ment was formed near Bolton, founded upon the employment of this 

 process. Thus was commenced the application of one of the many dis- 

 coveries contributory to the establishment of the great " Cotton Trade," 

 which has done so much to provide employment and create wealth for 

 the inhabitants of this country. 



Previously to the use of chlorine, bleaching was effected by the 

 exposure of fabrics to sunlight and air, and nearly all goods requiring to 

 be bleached for this country were sent to Holland or Germany, where a 

 period of many months was required before the operation was com- 

 pleted, and the goods returned to be finished ; whilst the same opera- 

 tion can now be effected in a few hours. 



It is obvious that without the discovery of some more rapid method 

 than the former one, we should have been compelled either to do with- 

 out bleached fabrics, or without the existing and astounding Cotton 

 manufacture. 



In the first instance chlorine was used in the state of solution in 

 water, but in this form its use was attended with grave inconvenience 

 to the workmen employed. This was remedied by the addition of 

 potash to the water, producing a solution called " Eau de Javelle " by 

 the first makers of it. 



The next step was to substitute lime for potash, thus producing so- 

 lution of chloride of lime. This was the idea of the late Mr. Charles 

 Tennant, of St. Rollox, who was engaged in business as a bleacher, and 

 a patent was granted to him for the invention in 1798, but this was set 

 aside in 1802. In 1799, Mr. Tennant obtained a patent for the manu- 

 facture of chloride of lime in the state of powder. 



