58 JOSIAS CHRISTOPHER GAMBLE 



leaden heads, incased in iron heated by the 

 circulation of hot water, saline solutions, or 

 by steam. 



Fifth, the mode of alternate charging of 

 the lime receivers, by which lime already in 

 part saturated with chlorine, is exposed to 

 the strongest gas, and the remnant of gas is 

 absorbed by a surface of fresh lime. 



From this patent dated the introduction of 

 the use of the "iron pot" in the decomposition 

 of salt, which, with various modifications, has 

 been continued up to the present day. But 

 some manufacturers, though they adopted 

 the apparatus so patented, maintained that 

 its principle was not patentable, and after 

 protracted litigation succeeded in releasing 

 themselves from any legal liability to pay 

 Gamble royalty for his invention, but Messrs, 

 Tennants, of Glasgow, who produced probably 

 three-fourths of all the bleaching powder then 

 made in the United Kingdom, and who had 

 bought Gamble's patent rights for the whole 

 of Scotland, declined to avail themselves of 

 this decision, and continued their annual 

 payment for the whole term of 14 years, for 

 which the patent was granted. Up to the 

 time they bought Gamble's Scotch patent the 

 Tennants worked the old method of making 



