82 Capt. P. Yorke's Experiments and Observations 



cising a feeble alkaline action on reddened litmus paper, is 

 rendered brown by sulphuretted hydrogen gas, and is made 

 turbid by sulphuric acid." 



4-. As I had not at this time seen these facts stated in any 

 other chemical work, I made the following experiments to 

 ascertain their exactness. I put some distilled water into a 

 glass, loosely covered so as to keep out dust, and filled a 

 phial fitted with a ground-glass stopper with distilled water. 

 I then arranged similar vessels with spring water, and into 

 each I put a slip of clean and fresh-cut lead. The spring water 

 used in this experiment I had previously ascertained to con- 

 tain in the gallon (of 10 pounds) 1*21 grain of the chlorides 

 of sodium and calcium, and 6*4? grains of carbonate of lime 

 held in solution by excess of carbonic acid (7^77^)- 



5. The spring water used in the above experiments with 

 lead was tested by sulphuretted hydrogen after the lapse of 

 three days, three weeks, and a year respectively, but never 

 gave any indication of holding lead in solution. The lead ac- 

 quired its usual dull surface at last, and became invested near 

 the surface of the water with oxide of a reddish and brownish 

 colour, much resembling in colour, but not in thickness, that 

 incrusting the leaden bullets described by Mr. Faraday in the 

 Journal of Science, vol. xvi. p. ] 63. The lead in the distilled 

 water and open vessel (a) in five days was covered near the 

 surface of the water by fine white flaky crystals radiating from 

 the lead. The water when tested by sulphuretted hydrogen 

 gave a brown tint. The same kind of action took place in the 

 stopped phial (b), but much slighter. In the open vessel, at 

 the end of three weeks, a quantity of the white crystalline 

 substance had accumulated at the bottom of the glass, and a 

 zone of pearly crystalline flakes of the same substance had 

 formed on the surface of the water, adhering slightly to the 

 glass and to the lead. A portion of this substance was col- 

 lected and dried at 212°. When treated with dilute acids it 

 dissolved : I did not perceive any effervescence. When heated 

 in a glass tube it gave off a portion of water and became yel- 

 low. 



6. The stopped phial, when examined after standing a year, 

 presented the following appearances. The bottom of the 

 phial was covered with about £ of an inch in depth of the white 

 crystalline substance before mentioned. The slip of lead it- 

 self was covered for about f rds of its length from the lower 

 end with brilliant laminar crystals (b) projecting from the lead 

 about 7 V tn °f an inch. When brushed off the lead and ex- 

 amined by reflected light, their colour was greenish grey, and 



