Chemistry and Physics. 321 
SCIENTIFIC INTELLIGENCE. 
I. CHEMISTRY AND PuHysIcs. 
methods were: “ 1st, that each process used should be as simple 
as possible, and should involve as little as possible of known 
liability to error; 2d, that different and independent processes 
should be resorted to as the means of checking each other’s re- 
sults, even though it may fairly be assumed that one is more 
advantageous than another; 3d, that each process should be 
carried out with quantities of material differing considerably from 
each other in successive experiments; and 4th, that only such 
of the Coast Survey, the relation of which to the kilogram of the 
Archives is known. The density of each weight used was deter- 
mined, as also that of all vessels and materials which had to be 
weighed. e barometer and thermometer being noted at the 
Produced by its oxidation. The ammonia alum 
carefully purified from iron, and repeated! recrystallized, was 
used in the first process, The aluminum hydrate was precipitated 
ffected in a platinum crucible, to the cover of which was attached 
& Wire carrying two perforated diaphragms to prevent the loss of 
