264 Researches on the Commercial Potash 



one hundred and forty five pounds. The general correctness of this 

 result is confirmed by the testimony of several intelligent manufac- 

 turers, with whom 1 have conferred. There is said also to be a great 

 saving of time in performing the operation. 



The above advantages are, of course, derived from the use of 

 small leach tubs and the employment of hot, instead of cold water; 

 by which the alkaline salt is more completely as well as more spee- 

 dily dissolved. 



Employment of Quicklime. — Another benefit resulting from this 

 process, arises from the mode in which the lime is mixed with the 

 ashes in alternate layers. It should here be distinctly observed, that 

 the effect of the employment of lime in the manufacture of potash, 

 depends altogether upon circumstances. When mixed with the 

 ashes, previous to the lixivation, the resulting alkali is more pure or 

 caustic, because the lime combines with the sulphuric and carbonic 

 acids existing in the sulphate and carbonate of potash, and forms 

 salts which are insoluble in water. This indeed is the mode in 

 which the pure potash of chemists is obtained. In the ordinary pro- 

 cess, the Hme is placed only in the bottom of a large tub ; but in the 

 one under consideration, it is distributed throughout the whole mass 

 of ashes, and thus its action is rendered more efficient. 



The correctness of these views is strikingly confirmed by M. Bec- 

 querel, who has ascertained by his numerous analyses of different 

 kinds of ashes, that those of the lime burner contain very little sul- 

 phate of potash, which is undoubtedly due to the action of the lime 

 upon the sulphate of potash with the assistance of charcoal. This 

 fact, M. Becquerel remarks, may lead to some advantage by adding 

 lime to the wood, the ashes of which are intended for the manufac- 

 ture of potash. [Lond. and Edinb. Phil. Mag. 1833.) 



The case, however, is very different, when the lixivium is treat- 

 ed with hme and boiled down, without a second filtration. It be- 

 comes then a fraudulent operation, because the salts of lime formed 

 by the decomposition of those of potash will all remain in the re- 

 sulting mass. And in the law regulating the inspection of Pot and 

 Pearl ashes, it is made the duty of every inspector to condemn every 

 cask thus adulterated ; a fact which can be very easily determined 

 by the want of solubility in the sample, and the effervescence of the 

 insoluble portion upon the addition of a dilute acid. 



Upon enquiry, I find it to be a common practice, to use lime in the 

 manner just described. — The reason which the manufacturers urge 



