Mr. A. B. Northcote on Parathionic Acid. 221 



darkening ; and the white residue is quite soluble in water, con- 

 tains no sulphurous, but abundance of sulphuric acid; its solu- 

 tion is strongly acid to test-paper, it is in fact anhydro-sulphate 

 of potassium. A portion fused with solid potash yielded no 

 alcohol, but gaseous products of very peculiar odour ; this expe- 

 riment, however, I hope to repeat in a more extended exami- 

 nation. 



The salt was crystallized for the last time from almost absolute 

 alcohol, in which it formed a nearly clear solution : the crystals, 

 when dissolved in water, gave no precipitate with chloride of 

 barium, showing that sulphate of potassium had been separated. 

 Yet some impurity has, I fear, remained behind, which has to a 

 certain extent vitiated the analytical results. 



Careful combustions were made, the substance being burnt in 

 a platinum boat in a stream of air and subsequently of oxygen ; 

 and in one instance the residue in the boat served for the deter- 

 mination of the potassium. The sulphur-determinations were 

 made by oxidizing the substance by concentrated nitric acid (in 

 which it dissolved perfectly in the cold), boiling it frequently with 

 the addition of a few drops of hydrochloric acid and precipitating 

 as barium salt — in the second analysis, evaporating the whole 

 to dryness and igniting in the presence of the chloride and ni- 

 trate of barium. The sulphate of barium was freed from oxide 

 from the decomposition of adherent nitrate before the final 

 weighing. In this manner the following results were obtained : — 



I. "3687 grm. of substance gave '1794 grm. of CO 2 , and 

 •0962 grm. of H 2 : it also left a residue of "208 grm., which 

 gave -543 grm. of K Pt CI 3 . 



II. -5016 grm. of substance gave '2450 grm. of CO 2 , and 

 •1311 grm. of H 2 0. 



III. -215 grm. of substance gave -318 grm. of Ba 2 SO 4 . 



IV. "160 grm. of substance gave '235 grm. of Ba 2 SO 4 . 

 These numbers lead to the following percentage composition, 



which may here be conveniently compared with that of sulph- 

 ethylate, or parathionate of potassium : — 



III. IV 



20-30 20-08 





I. 



I. 



C . 



. 13-27 



13-23 



H . 



, 2-89 



2-88 



K . 



. 23-51 



... 



S . 



, ,,, 



... 



. 



... 



... 



Mean. 



C-IPKSO 



13-25 



14-63 



2-88 



3-05 



23-51 



23-78 



20-19 



19-51 



40-38 



3903 



and hence arises the formula 



pl'S3 LJ-*7S vl'Ool'04 Q4-16* 



10021 100-00 



* 0=12, H=l, K = 39, S = 32, 0=16. 



