of Bronzes from Macliu Picchu, Peru. 



511 



others lie between these limits. In the lower left hand corner 

 of the diagram, fig. 1, the tin-concentration of each analyzed 

 bronze is indicated by a short vertical line at the corresponding 

 abscissa value. Where the neighboring concentrations differ 

 very little from one another, the lines run together and a general 

 survey of the distribution of these alloys according to tin- 



1100 



800 



500°. 



5 10 15 20 25 30 



Wt.% Sn. 



content can be gathered from the widths of the bands thus 

 produced. The mean average concentration of all specimens 

 analyzed lies in the neighborhood of 5.75 per cent tin. 



The abridged diagram, fig. 1, is drawn from data considered 

 most reliable by Guertler (13), who, in his Handbook of 

 Metallography, has critically reviewed the constitutional work 

 of various authors in this field (notably Heycock and Neville 

 and Shepherd and Blough). The more important concentra- 



Am. Jour. Sci. — Fourth Series, Vol. XL, No. 240. — December, 1915. 

 37 



