158 Intelligence and Miscellaneous Articles. 



addition of sulphuretted hydrogen a slight precipitate of sulphide of 

 lead was formed. In a similar experiment, where sulphuric acid was 

 substituted for sulphate of ammonium, a slight precipitate was pro- 

 duced by the sulphuric acid, and no precipitate could be obtained 

 afterwards with sulphuretted hydrogen. 



In two other experiments, where 5 cubic centims, of the acetate- 

 of-lead solution were mixed with 30 cubic centims. of the tartrate of 

 ammonium, no precipitate was produced by sulphate of ammonium 

 in the filtrate from the tartrate of lead, while sulphuric acid gave a 

 slight precipitate as before. In this case, however, sulphuretted 

 hydrogen gave a slight precipitate after sulphuric acid, as well as 

 after sulphate of ammonium. 



Normal Tartrate of Potassium mixed with the solution of sulphuric 

 acid exerted no solvent action on sulphate of lead. 



Succinate of Ammonium, prepared by neutralizing a solution of 

 succinic acid with ammonia- water, exerted no solvent action when 

 mixed with the free sulphuric acid ; but when mixed with the solu- 

 tion of sulphate of ammonium, 6 cubic centims. of the acetate-of-lead 

 solution were added to the liquor before a permanent precipitate fell. 



Normal Citrate of Ammonium Mas prepared by neutralizing a 

 weighed equivalent portion of crystallized citric acid with ammonia- 

 water. 10 cubic centims. of the solution were mixed with an equal 

 volume of the standard sulphuric acid, and the standard solution of 

 acetate of lead was dropped into the mixture in the usual way. No 

 permanent precipitate was formed until 16 cubic centims. of the lead 

 solution had been added. These 16 cubic centims. contained 0*6064 

 grm. of acetate of lead, corresponding to 0*4848 grm. of sulphate of 

 lead. The 10 cubic centims. of citrate-of-ammonium solution con- 

 tained 0*42 grm. of crystallized citric acid. Hence 1 part of sul- 

 phate of lead was held dissolved in the mixture of alcohol and dilute 

 sulphuric acid for every 0*8663 part of citric acid in the liquor.. 



On repeating the experiment, a precisely similar result was ob- 

 tained : 16 cubic centims. of the standard lead solution had to be 

 added to the mixture of alcohol and sulphuric acid before the preci- 

 pitate ceased to redisolve as fast as it formed. 



In two other experiments, where, instead of free sulphuric acid, 

 10 cubic centims. of the standard solution of sulphate of ammonium 

 were mixed with 10 cubic centims. of the citrate-of-ammonium solu- 

 tion, 30 cubic centims. of the standard lead solution had to be added 

 in each case before any permanent precipitate formed. 



Dicitrate of Ammonium (C 12 H 6 (NH 4 ) 2 O 14 ) was prepared in crys- 

 tals, and 22*6 grms. of the salt were dissolved in 500 cubic centims. 

 of the 18 per cent, alcohol. 25 cubic centims. of the solution were 

 mixed with an equal volume of the standard sulphuric acid, and the 

 acetate-of-lead solution was dropped into the mixture in the usual 

 way. After the addition of 8 cubic centims. of the standard acetate 

 of lead, a permanent precipitate was produced. These 8 cubic cen- 

 tims. contained 0*3032 grm. of acetate of lead, corresponding to 

 0*2424 grm. of sulphate of lead. The 25 cubic centims. of dicitrate- 



