138 ON BLEACHING. 



grounds of this decision were, that the patent included a mode of " bucking" 

 with quicklime and water, which was not a new invention ; and because 

 one part of the patent was not new, the whole of the claim must be set 

 aside ; and by this decision the use of liquid chloride of lime in bleaching 

 was thrown open to all. It was deemed an unfortunate circumstance that, 

 in consequence of an error of expression in describing his process, Mr 

 Tennant should be deprived of the fruits of a laborious investigation, 

 extending over several years. There was a strong feeling of sympathy 

 manifested, and the bleachers of Lancashire presented him with an 

 expression of their grateful acknowledgment by a service of plate, which 

 Mr Tennant accepted ; but it was most in accordance with the character of 

 his original design to press onward with his discoveries, and to bring his 

 first invention to a still more practical issue. He therefore adopted a new 

 method — one which at length he completed and secured by patent, for im- 

 pregnating quicklime in a dry state with chlorine, and in this instance his 

 right remained uncontested. He lived to enjoy his pecuniary reward ; and 

 the manufactory which he established in Glasgow is at this time the 

 largest in extent of any of the kind in Great Britain. The supply of 

 alkali, which was being derived from the burning of fern, and from the 

 incineration of sea-weecl on the coasts of Scotland and Ireland, having 

 become insufficient, it was supplemented by the importation of barilla, an 

 article produced in the same way upon the coasts of Spain, Sicily, and 

 Sardinia. The alkali procured by such means was very crude and very 

 unreliable in its action, and the use of it was at length superseded by 

 potash obtained from the clearing and burning of forests in the United 

 States. At length the consumption of the article had become so greatly 

 enlarged, and the price so enormously high, that the demand for the pro- 

 duction of alkali became an object of mercantile attention. Chemical 

 science stepped in, and very quickly responded to this appeal on the part 

 of the bleachers. The consequence was that an artificial soda was invented, 

 called " soda ash," or British soda, which, in regard to cheapness and 

 efficiency, has caused the bleachers to dispense with the use of potash ; 

 and the quality of the article has so successfully commended itself to the 

 consumers, that the manufacturers are now annually exporting British soda 

 of the value of one million sterling over and beyond the requirements of 

 the bleachers, soap-makers, and glass manufacturers of our own country. 

 It is worthy of remark that the great bulk of our shipments of British 

 soda are to the United States, from whence, only a short time ago, we were 

 importing very large quantities of potash, the production of their 

 forests. Thus, by an art which half a century ago was almost unknown, 

 and by the agency of our coal as fuel, we have succeeded in converting 

 certain products which we dig from under out feet, such as salt, pyrites, 

 and lime, into one of the most important branches of manufacturing 

 chemistry. These discoveries in chemistry may appear extraordinary, 

 although they are not more important in the economy of bleaching, than 

 are the mechanical arrangements which have superseded the exposure of 



