108 



Mr. E. Scliunek on the Colouring and 



[RecesS; 



they possess no interest. I may state, however, that it contained 40 per 

 cent, of oxide of lead and 35 per cent, of chloride of lead, and that the 

 composition of the remaining 25 per cent, of organic substance did not 

 dilfer very widely from that to which the preceding analysis conducted. 



E (1858). 



After having added to urine an excess, first of acetate and then of basic 

 acetate of lead, the liquid is found to have lost the greatest part of its 

 colour. Nevertheless it produces with ammonia a bulky precipitate, which 

 is similar in appearance to the two other lead precipitates, and also con- 

 tains some extractive matter. The object of this series of experiments was 

 to ascertain whether the composition of this portion of extractive matter is 

 the same as that of the portion contained in the two other precipitates. 

 A quantity of urine was accordingly mixed with acetate of lead, and then 

 with basic acetate of lead, until the latter gave no more precipitate. After 

 the liquid had become clear, it was decanted and mixed with an excess of 

 ammonia. The precipitate thereby produced was allowed to settle, filtered 

 off, completely washed, and then treated with dilute sulphuric acid in the 

 cold. The excess of the latter was removed by means of carbonate of lead^ 

 and the filtered liquid was evaporated as usual by a current of air. The 

 residue left on evaporation was treated with cold water, and the liquidj 

 after being filtered from the mixture of chloride of lead and extractive 

 matter {a) left undissolved, was evaporated as before. The syrupy residue 

 now left was well shaken with cold alcohol, which left a portion {b) undis- 

 solved. The filtered liquid was evaporated, and the residue having been 

 dissolved in a little alcohol, the solution v/as mixed with a large quantity of 

 ether, which made it milky and produced a copious syrup-like deposit (c). 

 This was allowed to settle, and the ethereal liquid was poured off and eva- 

 porated. The residue left on evaporation was dissolved in cold alcohol, 

 and to the solution there was added an alcoholic solution of acetate of 

 lead, which produced a precipitate containing much chloride of lead. The 

 addition of a little ammonia to the filtered liquid gave rise to a second 

 precipitate, which was filtered off, washed, and prepared in the usual 

 manner for analysis. 



I. 0'8405 grm. gave 0*5000 grm. carbonic acid and 0*1240 grm. water. 



I"1070 grm. gave 0*1595 grm. chloride of platinum and ammonium. 



0*5575 grm. ga;ve 0*5285 grm. sulphate of lead. 



In 100 parts it contained therefore 



C 16-22 



H 1*63 



N 0*90 



11*50 



PbO (^^'75 



100*00 



