160 



Disulphetholic acid is prepared by precipitating a solution of the 

 barium-salt with sulphuric acid, the excess of which is again removed 

 by digestion with oxide of lead, and subsequent treatment with sul- 

 phuretted hydrogen. It is a crystalline and stable compound, very 

 acid to the taste, and very deliquescent. With oxide of lead, or 

 with carbonate of silver, it readily forms the respective salts, both 

 of which are crystalline. 



After what has been said with reference to the action of sulphuric 

 acid upon acetamide, it is scarcely necessary to remark that the sul- 

 phopropionates and disulphetholates may be prepared with equal, or 

 even greater facility from propionamide. Care, however, should be 

 taken to use the amide in a perfectly dry state, which prevents in 

 great measure the formation of free propionic acid. 



PROPYL-SERIES. 

 Action of Sulphuric Acid upon Butyramide. 



Equal parts by volume of melted butyramide and Nordhausen 

 sulphuric acid evolve much heat when mixed together. In the re- 

 action two acids are eliminated, showing that the series bears a strict 

 analogy with the deportment exhibited by the preceding group. 



As the ammonia-salts of these acids are wholly uncrystallizable, 

 their separation is almost impossible. The barium-compounds also 

 are scarcely to be obtained of a definite form, so that it is a matter 

 of great difficulty to procure salts of sufficient purity for exact esti- 

 mation. Recourse was had to fractional precipitation by alcohol. 



The first salt which was deposited formed minute grains, which 

 adhered strongly to the sides of the glass vessel containing the solu- 

 tion. It gave a percentage of bariurp which unmistakeably indicated 

 the formula C 8 (H 6 Ba 2 ) S 2 O 10 , 



which is that of sulphobutyrate of barium. 



This substance in its reactions closely resembles (with the excep- 

 tion of its greater solubility in water) the corresponding body of the 

 ethyl-series. It burns like tinder, with evolution of sulphurous acid, 

 and leaves a residue of sulphite and sulphate of barium. The aque- 

 ous solution presents a gummy mass on evaporation. 



A further addition of alcohol to the mother-liquor of the sulpho- 

 butyrate of barium throws down a flocculent precipitate, which is 



