202 ANNUAL OP SCIENTIFIC DISCOVERY. 



that caustic baiyta will separate the sulphuric acid from a solution 

 of sulpliate of sodium, forming therewith an insoluble precipitate 

 of sulphate of barium, and leaving caustic soda in solution. The 

 decomposition of sulphate of sodium by caustic baryta is thus a far 

 sini])ler and readier process than its decomposition by Lcblanc's 

 method; but caustic baryta has hithei'to been, and is still, far too 

 costly to permit of its use for the decomposition of sulphate of 

 sodium on the great scale. ^lany attempts have been made to 

 obtain it at a cheap rate from sulijhate of barium, or " heavy spar," 

 which is a sufficiently abundant natural product, but they liave all 

 been utter failures ; and hence inventors liave sought sedulously 

 for some other and cheaper reagent, cai)ableof acting, as I'cgards 

 sulphate of sodium, in the same wa}'. !^Ir. Hunter has found a very 

 cheap one, indeed. lie has discovered that lime, by far the cheap- 

 est of all alkaline bodies, will separate the sulphmic acid from sul- 

 phate of sodium in solution, provided that the solution, after the 

 lime has been added to it, be subjected to a pressure consideral)ly 

 exceeding that of the atmosphere. He states that " either hy- 

 draulic, steam, or mechanical pressure," will answer equally well. 

 Unless the ai^plieation of the necessary pressure, on tin; large 

 scale, should prove to be attended with greater diflieu]ti(\s than 

 there seems any reason to antici])ate, his discovery will revolu- 

 tionize the soda manufacture ; and, by and by, all the carbonate 

 of sodium produced will be obtained by the direct coml)ination of 

 caustic soda with carbonic acid, the caustic soda being obtained 

 by a process embracing only two operations : (1.) the decomposi- 

 tion of chloride of sodium, or common salt, by sulphuric acid, as 

 in Leblanc's process; and (2.) the decomposition of the resulting 

 sulphate of sodium by lime. — Mechanics' Magazine. 



rHENIC OR CAKBOLIC ACID. 



Phenic acid, or phenylic alcohol, is usually accompanied by its 

 congenei's, xylic and cresylic alcohols, which adhere to it Avith 

 great tenacity, and give it the property of becoming brown in 

 contact with the air. For its puritication, M. Muller has recoiu'se 

 to a partial neutralization, and afterwards to the fractional distil- 

 lation of the product. 



The crude tar cedes to soda or lime water a mixture of the mat- 

 ters before mentioned, as well as naphthaline, which is soluble in 

 concentrated solutions of the alkaline iihenates. Water is added 

 to this until it ceases to cause a precipitate, when the liquid is 

 exposed in wide vessels, to facilitate the formation of the brown 

 bodies and their deposit. After filtering, the approximative quan- 

 tity of organic matter held in solution is determined, formed 

 principally of phenic acid and its congeners, which are easily 

 dis])laced by acids. 



The phenic acid is always the last to separate, so that it is easy 

 to disemliarrass it of its associated matter and In-own oxidized 

 products b}' adding carefully tlie proportion of acid determined by 

 calculation, so as to jireciijitate at first only these matters ; and, 

 by means of several trials, it is easy to arrive at the proper j^oint 



