212 Gooch and Boynton — Estimation of Barium 



Art. XX. — The Separation and Estimation of Barium 

 Associated with Calcium and Magnesium, by the Action of 

 Acetyl Chloride in Acetone Upon the Mixed Chlorides ; by 

 F. A. Gooch and C. N. Boynton. 



[Contributions from the Kent Chemical Laboratory of Yale Univ. — ccxviii.] 



In former papers from this laboratory* it has been shown 

 that certain chlorides may be quantitatively precipitated for 

 purposes of analysis by treating their water solutions with' 

 aqueous or gaseous hydrochloric acid and ether. 



The present paper is an account of procedure for the pre- 

 cipitation of barium chloride from water solution and its sepa- 

 ration from calcium and magnesium by the use of acetyl chloride 

 to decompose the water of the solution according to the reac- 

 tion CH3COCI + H 2 = CH3COOH + HC1, inconvenient vio- 

 lence of reaction being moderated by the addition of acetone 

 which mixes in all proportions with both acetyl chloride and 

 water and by itself exerts no appreciable solvent action upon 

 barium chloride. 



When a mixture of acetone and acetyl chloride, preferably 

 I : 1, is added slowly to a very concentrated solution of barium 

 chloride in water, the water is attacked at once, hydrogen 

 chloride is liberated, and precipitation begins immediately. If 

 the temperature is kepi; down during the process by immers- 

 ing in cool running water the vessel in which reaction takes 

 place, no more than a mere trace of barium can be detected by 

 sulphuric acid in the residue left after evaporating the liquid 

 separated from the precipitate by filtration through asbestos. 

 When, however, the temperature is allowed to rise, in conse- 

 quence of the heat liberated in the reaction, an appreciable 

 amount of barium may be found by sulphuric acid in the 

 filtrate. Below are given the data of experiments in which 

 the residue obtained (a) by treating a solution of barium 

 chloride in l cm3 of water with 30 cm3 of a 4 : 1 acetone-acetyl 

 chloride mixture and collecting the precipitate upon asbestos 

 in a perforated crucible, washing with acetone and with ether, 

 was weighed after drying in air, then (b) treated on the asbes- 

 tos for ten minutes with 15-20 crn3 of acetyl chloride, washed 

 with acetone and with ether, dried in the air and weighed, 

 then (c) digested for ten minutes with 20-25 cm3 of 2 : 1 ace- 

 tone-acetyl chloride mixture, washed with acetone and with 

 ether, dried in the air and weighed, and then (d) heated in the 

 air-bath, or to low redness, and weighed. 



* Mar, this Journal [3J, xliii, 521 ; Havens, this Journal [4], ii, 416 ; iv, 

 111 ; vi, 45 ; vi, 396. 



