JAMES SHANKS 211 



stances, it seems improbable that this process, 

 ingenious as it is, will be extensively 

 adopted." 



We now know how accurate this forecast 

 was, still the patent is an instance of Shanks' 

 inventive ingenuity. 



The only other patent with which his name 

 is associated is one " to improve the manu- 

 facture of caustic soda and caustic potash," 

 taken out in December, 1863. 



His process is thus described : First, the 

 dessication and oxydation (when such oxyda- 

 tion is required) of a mixture of carbonate of 

 soda or of potash, as the case may be, by 

 heating the same in a reverberatory furnace, 

 or other suitable apparatus with access of air, 

 and then producing a dry compound in a 

 state favourable for the extraction of caustic 

 soda or caustic potash by lixiviation and 

 filtration. Solutions of carbonate of soda or 

 solutions ordinarily occurring in the manu- 

 facture of soda, and known as blackish liquors 

 or red liquors, are employed. If these 

 solutions are not already in a state of satura- 

 tion, or nearly so, they are concentrated until 

 carbonate of soda crystals begin to deposit, 

 when the quantity of carbonate of soda 

 contained in the liquid is estimated, and 



