on the Action of Water and Air on head, 87 



substance thus obtained is a definite compound or a mixture; 

 but if 223 '4 represent two equivalents of oxide of lead, 22*1 

 carbonic acid, and 9 water, then a substance which should 



consist of 2 Yb + C-\-Aq would contain in 100 parts, 



Oxide of lead 87*9 



Carbonic acid 8*6\ 19 , 



Water 3'5 J ~ 



100- 

 and might also be represented by {Pb + C} + {Fb + Aq}. 



20. When a portion of this substance was put into a stop- 

 ped phial with distilled water, and the water tested after some 

 days by sulphuretted hydrogen, it gave a barely perceptible 

 brown tint. 



When some of the substance slightly moistened was ex- 

 posed freely to the air two or three hours, it dissolved in acids 

 with brisk effervescence, like common carbonate of lead. 



Of the Solution of Lead in distilled Water. 



21. In order to show the power the aqueous solution of 

 oxide of lead possesses of reddening turmeric paper, it is suffi- 

 cient to put a single slip of fresh-cut lead into a phial of di- 

 stilled water which has been agitated with air, and introduce 

 with it a bit of turmeric paper : in two or three hours the pa- 

 per will be permanently reddened. 



22. The liquid obtained by experiment 8, and others si- 

 milarly conducted, has the following properties: 1. it reddens 

 turmeric paper easily, and restores the blue of reddened litmus 

 paper ; 2. it gives a deep brown colour with a solution of sul- 

 phuretted hydrogen, and soon deposits a black precipitate; 

 3. it becomes immediately very turbid on the addition of di- 

 lute sulphuric acid; 4. also with a solution of carbonic acid; 

 5. turbid with a solution of sulphate of soda, — the effect much 

 increased by a drop of sulphuric acid ; 6. an equal effect with 

 bisulphate of potash. With a drop of a solution of iodide of 

 potassium, it gave a white cloud, which on the addition of a 

 drop of very dilute muriatic acid became orange-yellow, and 

 deposited a yellow precipitate of iodide of lead. With a so- 

 lution of common salt it immediately becomes turbid ; also 

 the same with the solution of sulphate of lime, containing 

 T o\jo tft of that salt ; slightly turbid with a solution of nitre. 



With neutral chromate of ammonia it preserved its trans- 

 parency; but when a very minute quantity of acetic acid was 

 added, it deposited a yellow precipitate. 



