of the State of New YorTc. 265 



is, that its addition to the ley while boiling, assists in " keeping back 

 the nitre" as they term it, and thus facilitating the subsequent steps 

 of the process. By " the nitre" is undoubtedly meant the sulphate 

 of potash, which, being much less soluble than any of the salts con- 

 tained in the ashes, begins to crystallize long before the others, and 

 forming a solid crust, proves somewhat troublesome, and should be 

 removed, if the quantity be considerable. Instead of this, however 

 the manufacturers add lime, which, by decomposing this salt form.s 

 the sulphate of hme and this with the portion of lime not acted on, 

 falls to the bottom of the kettle, while the potash resulting from the 

 decomposition of the sulphate, enters into other combinations. The 

 lime rapidly absorbing carbonic acid from the air, is converted into 

 carbonate of lime, and hence carbonate and sulphate of lime consti- 

 tute the largest proportion of the insoluble matters, which are often 

 found in such large quantity in our samples of potash. 



I have been the more particular upon this point because, in the 

 original specification of the patent now under consideration, it was 

 proposed to add lime to the lixivium, a practice which, however gen- 

 eral it may be, I have uniformly condemned. But I have the depo- 

 sitions of two manufacturers, and the assurances of several others, 

 that more recently, the mode adopted is that which I have given 

 above, and in which it will be observed that such addition is 

 omitted. 



Addition of Common Salt. — The addition of this substance to 

 the lixivium is a most unwarrantable practice, as it injures the quality 

 of the potash, while its presence cannot easily be detected. The 

 reason of this will be apparent, from the fact long known to chem- 

 ists, that when common salt is added to carbonate of potash in solu- 

 tion, a double decomposition takes place, the result of which is the 

 formation of chloride of potassium and carbonate of soda ; the for- 

 mer being almost wholly useless, and the latter being employed for 

 purposes, other than those to which common potash is ordinarily 

 apphed. 



The danger attending the adulteration is, that the chloride of po- 

 tassium and carbonate of soda thus formed, are both highly soluble 

 in water, so that they would escape detection by the ordinary mode 

 of inspection, and samples in which they were contained in consid- 

 erable quantity, be branded as " first sort." 



The reason advanced by the manufacturers in favor of the use of 

 salt, is that it facilitates the "melting of the potash." But this 



Vol. XXIX.— No. 2. 34 



