TO OUR READERS AND CORRESPONDENTS. 



Mr. T. Hamilton will observe that we have availed ourselves of 

 his information. 



The remainder of Mr. Bigsby's paper, with the illustrative en- 

 gravings, will certainly appear in our next Number, the whole of 

 his communication will thus be comprised in the same volume of this 

 Journal. 



Wc do not observe any thing sufficiently new in the process for 

 obtaining Cinchonia, with which we have been favoured by our 

 correspondent in Paris, to induce us to insert it in this Journal. The 

 use of muriatic acid and magnesia was long ago suggested by Badol- 

 lier, and answers the purpose, but we prefer sulphuric acid and lime. 

 Our experience leads us to regard quinia, or at least its sulphate, as 

 more certain and effective than the corresponding salt of Cinchoni. 

 Its liability to adulteration we have long been aware of. A quantity 

 recently imported from Paris contained 20 ])er cent, of sulphate of 

 magnesia and sulphate of lime. 



We refer our correspondent " on the Separation of Lime and 

 Magnesia," to Mr. Davies' ingenious paper in the Annals of Phi- 

 losophy for last August. We were not aware of the solubility of 

 sulphate of magnesia, and the perfect insolubility of sulphate of lime 

 in alcohol of the specific gravity which he adverts to, and have 

 hitherto been prevented from submitting his suggestions to the test of 

 experiment. 



