an Impurity of Metallic Zine. 385 
The chemically pure sulphuric acid, so called, manufactured by Rosen- 
garten, of Philadelphia, was purer than the commercial acid with refer- 
P . 
aminations for arsenic by Marsh’s process. To the “ chemically pure 
sulphuric acid made by Powers and Weightman of Philadelphia, pre- 
cisely the same remarks apply; it is unfit for use in any research where 
the process, concentrated and condensed into a very small compass. *OF 
example, in a poisoning case in which the chemist is obliged to destroy 
Certainly possible, the theory be true. : 
. JOUR. Scr.—SEconp Serres, VoL. XXXII, No. 96.—Nov., 1861, 
' 49 
