Sanger and Black.— Arsenic by Gutzeit Method. 



Plate 2. 



;4 



mm 



ill 



2 5 10 15 20 25 30 35 40 50 60 70 



Fig. 



Standard Arsenic Bands in Micromilligrams of As^Oa 

 Ammon:a Development. 



Proc. Amer. Acad. Arts and Sciences. Vol. XLIII. 



