96 Correspondence of J. Nickles. 
which made thirty revolutions a minute in driving a blast 
may be used as pasturage for cattle for several years, without 
the roots, at the end of this time, losing any of their tinctorial 
qualities. 
submitted to the examination of competent men; and t 
From these observations it results, that we may make, without 
great expense, artificial meadows on land deprived of any means — 
of irrigation, and derive a crop of madder having all its coloring 
principle preserved. | 
Toxicology.— Researches on Arsenic_—Dr. Blondlot of Nan¢ 
has just observed a fact which explains the contradictions e” 
countered by inexperienced chemists in attempts to detect arse”! 
in connection with organic matters. It is this:—that when s™ 
