^S PREClPiTAnOxV OF OXIDES BY TH1EIR OWN METALS. 



Experiments with solutions of lead, watery acidulated waUr, 

 and lead. 



Exp. with nU 10. A chain was formed with four ounces of a solution of 

 tratpoflead. nitrate of leiid made without heat, foitr ounces of water, 

 and a slip of lead an inch broad, six inches long, and half 

 an inch thick, tixcd in a piece of cork laid across the top 

 of the glass. Immediately a point of was perceived, where 

 the liquors were in contact, ,and this continued growing 

 broader and more perceptible during the course of an hour. 

 Above thib point the brightness of the lead continued di- 

 ijiinisliing; and below small shining metallic laminae were 

 deposited, which increased for 24 hours. At the end of 

 this time the liquors had mixed, and destroyed the chain. 

 The metallic laminae, which were pure lead, had no regu- 

 lar figure. 

 JJitratc'oflead, H' To Icarn what would be the action of a similar chain, 

 A water iicidu- if ypidylo^is yvjjjgf were emploved, I repeated the experi- 

 Jated with ni- • i i , .■ • f i i !• • i i 



trie acid, meut with the addition oi two drachms ot acid to the water. 



Soon after a brighter place was observed where the two li- 

 quors were in contact ; above this gas was extricated, and 

 white oxide was formed ; while below the slip of lead grew 

 dull. After the expiration of twenty-four hours oxide was 

 formed at this place also, and gas was evolved. At this 

 period the liquors had mingled together, without any sepa- 

 ration of metallic lead. According to all appearance there 

 had been no very active chain, because the liquors mixed 

 too soon. To verify this supposition, I made the following 

 experiment. 

 Warm solution ' -• Four ounces of boiling distilled water were saturated 

 of nuratj (f yj,",ti-, nitrate of lead, and put milk-warm into a cylindrical 

 !&tcd water. g^a^s. Four ounces of water acidulated with an ounce of 

 nitric acid at 1*25 beinj^ added upon the solution, the chain 

 was completed with a slip of polished lead. A point was 

 formed, that appeared more shining than in the preceding 

 or following experiments. The part of the lead in the 

 acidulous water was covered with a great many bubbles of 

 pas, and became gray. On the edges of the slip that were 

 JMimersed in the solution were deposited filaments, which 

 at the expiration of some hours increased, so as to form 



little 



