ARSENIC, ANTIMONY, BISMUTH. COPPER AND LEAD. 263 



through them has been ascertained by a skillful chemist to 

 have the protective ingredients alluded to in it. There has 

 been great carelessness in this matter. Because in the 

 majority of cases there is no hazard, people have presumed 

 on safety without any examination, foolishly running the 

 risk of having the exception occur in their case. 



Tin-lined pipes are said to be safer than ordinary lead 

 pipes. 



373. Sugar of Lead, or Lead Acetate, Pb(C 2 H 3 O 2 ) 2 . Ace- 

 tate of lead is commonly called sugar of lead, on account 

 of its sweet taste. A very pretty experiment may be tried 

 with a solution of this salt. Dissolve 15 grammes of sugar 

 of lead in ISO cubic centimeters of water, making the liq- 

 uid clear by adding a few drops of acetic acid. If this 

 be poured into a phial, and a slip of zinc be fastened to the 

 cork, as seen in Fig. 98, brilliant metallic branches will 

 grow upon the zinc, filling the phial 

 in a day or two. These are crystals 

 of lead which have arranged them- 

 selves in this arborescent form. This 

 is because the zinc replaces the lead 

 in the lead acetate, forming zinc ace- 

 tate, which takes the place of the 

 lead acetate in the liquid. This 

 leaves the lead uncombined, and its 

 particles, as fast as they are released, 

 gather in crystals, the process taking its start from the 

 zinc where the chemical change occurs. Acetic acid is 

 H.C 2 H 3 O 2 , being an organic acid composed of carbon, hy- 

 drogen, and oxygen, in the proportions named. Lead ace- 

 tate is Pb(C 2 H 3 O 2 ) 2 , therefore the reaction above described 

 may be expressed in an equation thus : 



Lead acetate. Zinc. Zinc acetate. Lead. 



rb(C a II,O a )a + Zn = Zn(C 3 H 3 3 ) 2 + Pb 



