XI, A, 4 



Witt: Testing of Galvanized Iron 



155 



decant the solution from the lead and then to heat the latter 

 with sulphuric acid until it was completely disintegrated. After 

 cooling, the mixture was added to the solution which precipitated 

 all the lead as sulphate. The new mixture was then cooled, 

 transferred to a 2-liter flask, and made up to volume. The lead 

 sulphate settled completely, and portions of the clear solution 

 were withdrawn and analyzed. The iron was precipitated with 

 ammonia and determined gravimetrically. The zinc was deter- 

 mined by titration with potassium ferrocyanide. 



In the hydrochloric acid solution it was only necessary to 

 oxidize the iron with nitric acid, add some ammonium chloride, 

 and then precipitate with ammonia. 



Tables II and III show the results obtained by the two methods. 



Table II. — By hydrochloric acid method.^ 



No. 



Initial 

 tem- 

 pera- 

 ture. 



Final 

 tem- 

 pera- 

 ture. 



Total 

 loss in 

 weight. 



By analysis. 



Calculated to ounces per square foot. 



Zinc (a). 



Iron (b). 



b 

 a+b 



Zinc by 

 analysis. 



Iron by 

 analysis. 



Total 



Zn+Fe 

 by anal- 

 ysis. 



1 



Total loss 

 in acid. 



1 

 2 

 3 



4 

 5 



°C. 

 31 

 30 

 30 

 30 

 30 



45 

 45 

 46 

 43 



44 



Gram^. 

 17.6155 

 18. 3519 

 19.4566 

 17.6164 

 17.7744 



Grams. 

 16. 9289 

 17. 5152 

 18. 6183 

 16. 9879 

 17.1068 



Gram^. 



0.7583 

 0. 7757 

 0. 7828 

 0.7583 

 0.7271 



Per cent. 

 4.29 

 4.26 

 4.00 

 4.29 

 4.08 



2.45 

 2.55 

 2.71 

 2.46 

 2.49 



0.11 

 0.11 

 0.11 

 0.11 

 0.11 



2.56 

 2.66 

 2.82 

 2.57 

 2.62 



2.66 

 2.67 

 2.83 

 2.66 

 2.59 



^ The hydrochloric acid solution contained 19.53 per cent HCl (density, 1.098). A 

 separate portion (400 cubic centimeters) was used for each sample. All samples were 15 by 

 15 centimeters and were cut from the same sheet, washed in benzol, dried, and weighed. 



Column four shows the loss of weight suffered by each sample in the hydrochloric acid. 

 These values multiplied by four give grams per 900 square centimeters. The acid solution 

 was analyzed for iron and zinc. These results are shown in columns five and six. The last 

 two columns show the very close agreement between the total zinc and iron determined by 

 analysis and the total loss in acid. 



Table III. — By lead acetate method.' 



No. 



Temper- 

 ature. 



Total loss 

 in weight. 



By analysis. 



Calculated to ounces per square foot. 



Zinc (a). 



Iron (b). 



b 

 a+b 



Zinc by Iron by 



analysis, analysis. 



Total 

 Fe+Zn 

 by anal- 

 ysis. 



Total loss 

 in lead 

 acetate. 



1 

 2 

 3 



°C. 

 30 

 30 

 30 



Gram^. 

 17. 3354 

 17. 8257 

 18.4110 



Grawta. 

 16.9007 

 17. 3119 

 17.8625 



Grams. 



0. 5698 

 0. 7217 

 0.6105 



Per cent. 

 3.26 

 4.00 

 3.30 



2.46 

 2.52 

 2.60 



0.08 

 0.10 

 0.09 



2.54 

 2.62 

 2.69 



2.52 

 2.69 

 2.68 



• Fifteen-centimeter squares cut from the same sheet as those used in the hydrochlorie 

 acid method were placed in 500 cubic centimeter portions of lead acetate solution. No ap- 

 preciable rise in temperature took place. 



