156 Intelligence and Miscellaneous Articles. 



certain proportion of lead could be held dissolved in presence of sul- 

 phuric acid, even in an alcoholic solution like wine, by the action of 

 various soluble alkaline salts capable of decomposing and of being 

 decomposed by sulphate of lead ; for it is a well-known fact that very 

 considerable quantities of sulphate of lead can be held dissolved in 

 water by means of many acetates, citrates, and tartrates, and by va- 

 rious other salts. 



To test this idea, the following set of experiments has been carried 

 out at my suggestion by Mr. A. H. Pearson, of Haverhill, a student 

 in the Laboratory of the Massachusetts Institute of Technology. 



A considerable quantity of dilute alcohol, of the usual strength of 

 sherry wine (18 per cent.), having been prepared, standard solutions 

 of acetate of lead, of sulphuric acid, and of sulphate of ammonium 

 were made by dissolving weighed quantities of these substances in 

 portions of the 18 per cent, alcohol. Each of the solutions was made 

 of such strength that 500 cubic centims. of the liquid contained one- 

 tenth of an equivalent of the salt or acid, reckoned in grammes, on 

 the hydrogen scale. 



Alcoholic solutions of several salts of ammonium and of the fixed 

 alkalies were also prepared, as will be described below. 



In each experiment, equal quantities of the standard solution of 

 sulphuric acid, or of sulphate of ammonium, and of the saline solu- 

 tion to be tested, were mixed in a glass flask, and the standard solu- 

 tion of acetate of lead was made to fall from a burette drop by drop 

 into the mixture until a persistent precipitate of sulphate of lead was 

 perceived. The burette was graduated so that two drops from it 

 were equal to one-tenth of a cubic centimetre ; and the flask was 

 constantly shaken while the drops of acetate of lead were falling 

 into it. 



The results of the experiments are as follows : — 

 Acetate of Ammonium was prepared by neutralizing ordinary acetic 

 acid with ammonia-water ; and the strong aqueous solution thus ob- 

 tained was mixed with alcohol. It appeared, however, that this 

 alcoholic solution of the acetate exerted no solvent action upon sul- 

 phate of lead ; for a permanent precipitate of the latter was produced 

 in the mixture of acetate of ammonium and normal sulphuric acid 

 by the first drop of the standard solution of acetate of lead. The 

 same negative result was obtained in several repetitions of the ex- 

 periment, even when new portions of dilute alcohol and a second set 

 of the standard solutions were employed. 



When, however, the solution of acetate of ammonium w r as mixed 

 with an equal bulk (10 cubic centims.) of the standard solution of 

 sulphate of ammonium instead of the sulphuric acid, a considerable 

 quantity of sulphate of lead was held in solution by it. In two di- 

 stinct trials, the precipitate formed by dropping acetate of lead into 

 the mixed solution of acetate and sulphate of ammonium continued 

 to redissolve until 3 cubic centims. of the standard solution of acetate 

 of lead had been added to the liquor. These 3 cubic centims. of the 

 standard solution contained 0*1137 grm. of acetate of lead, corre- 



