viii, a, 6 West: Analysis and Composition of Red Lead 



433 



Table II shows the combined lead monoxide content cor- 

 responding to each of a series of mixtures of the oxides Pb 3 4 

 and Pb 4 B , ranging from pure Pb 3 4 to pure Pb 4 B . 



Table II. — Mixtures of lead oxides and the corresponding combined PbO 

 content of each mixture. 



Mixture. 





1 Mixture. 





Mixture. 





! Mixture. 





Mixture. 









Com- 

 bined 

 PbO. 



i 





Com- 

 bined 

 PbO. 







Com- 

 bined 

 PbO. 







Com- 

 bined 

 PbO. 







Com- 

 bined 

 PbO. 



O 



CO 



JO 

 fit 



O 



cm 



1 o 



CO 



— 



Ph 



O 



Ph 



O 



CO 



■a 

 Ph 



J!" 



Oh 



Ph 



o 



Ph 



O 



CO 



■a 



Ph 



ib 



o 



Ph 



P.et. 



P.ct. 



P. cent. 



P. Ct. 



P.ct. 



P. cent. 



P.ct. 



P.ct. 



P. cent. 



P.ct. 



P.ct. 



P. cent. 



IP. ct. 



P.ct. 



P. cent. 



100 







65.11 



80 



20 



66.82 



60 



40 



68.54 



40 



60 



70.25 



20 



80 



71.97 



99 



1 



65.19 



! 79 



21 



66.91 



59 



41 



68.62 



39 



61 



70.34 



19 



81 



72.05 



98 



2 



65.28 



78 



22 



66.99 



58 



42 



68.71 



38 



62 



70.42 



18 



82 



72.14 



97 



3 



66.36 



77 



23 



67.08 



67 



43 



68.79 



37 



63 



70.61 



17 



83 



72.22 



96 



4 



65.45 



76 



24 



67.17 



66 



44 



68.88 



36 



64 



70.59 



16 



84 



72.31 



96 



5 



65.54 



75 



25 



67.25 



55 



45 



68.97 



35 



65 



70.68 



15 



85 



72.39 



94 



6 



65.62 



74 



26 



67.34 



54 



46 



69.05 



34 



66 



70.76 



14 



86 



72.48 



93 



7 



65.71 



73 



27 



67.42 



53 



47 



69.14 



33 



67 



70.85 



13 



87 



72.56 



92 



8 



66.79 



j 72 



28 



67.51 



52 



48 



69.22 



32 



68 



70,94 



12 



88 



72.65 



91 



9 



65.88 



: 71 



29 



67.59 



51 



49 



69.31 



31 



69 



71.02 



11 



89 



72.74 



90 



10 



65.97 



70 



30 



67.68 



50 



50 



69.39 



30 



70 



71.11 



10 



90 



72.82 



89 



11 



66.06 



69 



31 



67.77 



49 



51 



69.48 



29 



71 



71.19 



9 



91 



72.91 



88 



12 



66.14 



68 



82 



67.85 



48 



52 



69.67 j 



28 



72 



71.28 



8 



92 



72.99 



87 



IS 



66.22 



67 



33 



67.94 



47 



53 



69.65 | 



27 



73 



71.37 



7 



93 



73.08 



86 



14 



66.31 



66 



34 



68.02 



46 



54 



69.74 



26 



74 



71.45 



6 



94 



73.16 



85 



15 



66.39 



65 



35 



68.11 



45 



65 



69.82 



25 



75 



71.54 



5 



95 



73.25 



84 



16 



66.48 



64 



36 



68. 19 



44 



66 



69.91 



24 



76 



71.62 



4 



96 



73.35 



83 



17 



66.57 



63 



37 



68.28 1 



43 



57 



69.99 



23 



77 



71.71 



3 



97 



73.42 



82 



18 



66.65 



62 



38 



68.37 | 



42 



58 



70.08 



22 



78 



71.79 



2 



98 



73.61 



81 



19 



66.74 



61 



39 



68.45 



41 



59 



70.17 



21 



79 



71.88 



1 

 



99 



100 



73.69 

 73.68 



—-\—~ 



| 















In estimating the purity of samples of red lead, the following 

 method is satisfactory. By determining the amount of combined 

 PbO and referring to Table II, one may ascertain the amount of 

 each of the oxides Pb 3 4 and Pb 4 5 . The calculated total lead 

 content of the sample checks with the percentage of total lead as 

 obtained by direct determination. 



METHOD OF ANALYSIS 



a. Insoluble matter. — Baucher's method 8 gives very good re- 

 sults for this determination, and may be carried out satisfactorily 

 in the following manner: 



A 2-gram sample is treated with 100 cubic centimeters of 10 

 per cent nitric acid solution; after a few minutes' boiling, the 

 red lead is completely decomposed, leaving only the black lead 



'Petit Monit. Pharrru, 47, 2651. 



