18 § 23. REAGEISTTS. 



the gas in the gasometer ; for use, conduct it from the 

 gasometer through a solution of caustic potash (Sp. Gr.= 

 1.27) in a Liebig's potassa-bulb, then through a U tube 

 containing pumice-stone soaked in sulphuric acid, and 

 finally through a tube containing calcic chloride. 



Phosphorus salt. — See sodlc ammonic phosphate. 



23. Platinic chloride.— PtCl^. (Bichloride of plat- 

 inum. PtCl^.) — Its solution, evaporated to dryness on 

 the water-bath, should leave a residue entirely soluble in 

 alcohol. 



Precipitates and solutions containing platinum should 

 be throAvn into a bottle containing a solution of ammonic 

 chloride. When a sufficient quantity of the precipitate 

 has accumulated, separate it from the liquid by filtration, 

 wash, dry, and ignite it strongly. Exhaust the residue 

 thoroughly with hot nitric acid, wash the insoluble part 

 in water, dissolve in aqua regia with the aid of a gentle 

 heat, adding fresh portions of nitric acid until the j^lat- 

 inum is completely dissolved, evaporate the solution on 

 the water-bath, w^ith the addition of hydrochloric acid, 

 and dissolve the semi-fluid residue in 10 parts of water. 



24. a.— Plumbic acetate.— Pb (CJI3OJ.. (Acetate 

 of lead. PbO, CJI3O3. PbOA.)— The haslc acetate, 

 Ph {CJI^O^„ 2 PbO, is prepared by treating 120 grms. 

 of crystallized common acetate (sugar of lead) with 60 

 grms. of gently ignited, and then finely pulverized plumbic 

 oxide (litharge), and 400 c.c. of water ; let the mixture 

 stand some time in a warm place with frequent agitation, 

 and finally filter the liquid for use. 



h. Plumbic binoxidc. — PbO^. 



c. Plumbic oxide. — PbO. IJtharge. 



25. a. — Potassic acetate. — KC^fi,. (Acetate of po- 

 tassa. KO,C^H303.) — This should be white and free from 

 cmpyreumatic odor. Dissolve in 5 parts of water. 



