159 



state of purity. It was finally obtained by acting upon propion- 

 amide with anhydrous phosphoric acid. 



When three parts by measure of the nitrile are cautiously mixed 

 with two parts of fuming sulphuric acid, and heat is applied, the 

 liquids enter into a sort of ebullition, carbonic acid being copiously 

 evolved; at the same time a portion of propionic acid passes into 

 the receiver, the amount of which may be lessened by raising the 

 temperature only gradually. 



At the close of the operation a tenacious mass is found in the 

 retort, which, when dissolved in water and neutralized with carbonate 

 of barium, furnishes two rather soluble but readily crystallizable salts, 

 very difficult to separate one from the other. Their isolation may 

 be conveniently effected, by converting them into the corresponding 

 ammoniacal compounds, by precipitating their solution with car- 

 bonate of ammonium. 



The filtrate yields two substances, one of which crystallizes, while 

 the other is quite uncrystallizable. 



The latter substance, when long digested with carbonate of barium, 

 produces crystals of a barium-salt whose analysis gives numbers lead- 

 ing to the formula 



This substance is obviously sulphopropionate of barium, the com- 

 pound next in series to the sulphacetate discovered by M. Melsens. 



It is generally deposited from its solution in fine silky crystals, 

 which arrange themselves in spherical groups. They are very stable, 

 and bear a high temperature without decomposition. 



The salt associated with the uncrystallizable sulphopropionate of 

 ammonium crystallizes with ease, either in rectangular prisms or 

 in octohedra. Similarly converted into a barium- compound, it was 

 found by analysis to contain at 100 C., 



C 4 (H 4 Ba 2 )S 4 12 + 2HO. 



It forms regular six-sided plates, which are moderately soluble in 

 water, but insoluble in alcohol and in ether. It loses two equiva- 

 lents of water of crystallization between 100 and 170, but a few 

 degrees above this temperature it is decomposed with blackening, 

 yielding water, sulphurous acid, volatile organic products, and sul- 

 phate of barium. 



We designate this salt as disulphetholate of barium. 



