Intelligence and Miscellaneous Articles. 157 



spending to 0*0909 grm. of sulphate of lead. To hold dissolved one 

 part of sulphate of lead in the dilute alcohol charged with sulphate 

 of ammonium, there was consequently required 110 cubic centims. 

 of a tolerably strong solution of acetate of ammonium. 



Still another experiment with sulphuric acid was made, by mixing 

 10 cubic centims. of an entirely new preparation of acetate of ammo- 

 nium with a similar quantity of the standard solution of acetate of 

 lead, and dropping the standard sulphuric acid into the mixture. No 

 persistent precipitate was produced in this case until 5 cubic, cen- 

 tims. of the acid had been added. This quantity of the standard acid 

 contained 0*049 grm. of sulphuric acid, corresponding to 0*1515 

 grm. of sulphate of lead; hence only 33 parts of the solution of ace- 

 tate of ammonium were required to dissolve 1 part of sulphate of 

 lead. It is to be observed that the insolubility of tartrate, citrate, 

 and succinate of lead in alcohol prevents the application of this mo- 

 dified form of the experiment in the examples given below. With 

 the exception of the acetates of ammonium and sodium, none of the 

 salts experimented with can be mixed with the acetate of lead and 

 subsequently tested with sulphuric acid or sulphate of ammonium. 



Acetate of Sodium, whether mixed with the normal sulphuric acid, 

 with sulphate of ammonium, or with acetate of lead, seemed to have 

 no solvent action upon sulphate of lead. 



Neither Oxalate of Ammonium nor normal Oxalate of Potassium 

 exerted any solvent action either in presence of the sulphuric acid or 

 the sulphate of ammonium. 



Tartrate of Ammonium. — Normal crystallized tartrate of ammonium 

 was dissolved in alcohol of 18 per cent., in such proportion that 500 

 cubic centims. of the solution contained one-tenth of an equivalent 

 (18*4 grms.) of the salt. 25 cubic centims. of the solution was mixed 

 with an equal volume of the normal sulphuric acid, and normal ace- 

 tate.of lead was added to the mixture until a permanent precipitate 

 was produced. To effect this result, there was required of the stan- 

 dard solution of acetate of lead 2 cubic centims. or 0*0758 grm. of 

 the acetate, corresponding to 0*0606 grm. of sulphate of lead. The 

 25 cubic centims. of the solution of tartrate of ammonium contained 

 0*92 grm. of the dry salt. Hence something more than 15 parts of 

 tartrate of ammonium are required to hold 1 part of sulphate of lead 

 dissolved in dilute alcohol containing free sulphuric acid. 



In two other experiments, where the tartrate-of-ammonium solu- 

 tion was mixed with the sulphate of ammonium instead of with free 

 sulphuric acid, 3 cubic centims. of the acetate-of-lead solution had 

 to be added before a permanent precipitate could be formed. 



That sulphuric acid is a more efficient precipitant of lead in pre- 

 sence of tartaric acid than sulphate of ammonium was shown in an- 

 other way. 30 cubic centims. of the standard alcoholic acetate of 

 lead were mixed with an equal volume of the standard solution of 

 tartrate of ammonium. The precipitated tartrate of lead was filtered, 

 and the filtrate mixed with a quantity of the sulphate-of-ammonium 

 solution. No precipitate was produced, though on the subsequent 



