44 
not contaminated by finer particles by the water it is shaken 
in remaining almost clear. The same process is carried out 
with the sediment in the second vessel, only permitting each 
charge of water to stand longer than in the first case, as the 
forms are now much smaller and require longer to settle. In 
this way we may get three or four densities of sediment, 
although I found that my specimen yielded but two which 
contained anything of interest of a calcareous nature. After, 
then, setting aside the two first sediments, I carefully acted 
upon what was left with Hydrogen Nitrate (Nitric Acid) and 
procured a small quantity of a sediment consisting for the 
most part of nothing but the siliceous lorica of Diatomacev. 
They were very few, however, so, to procure all the remains 
of Diatomaceve and other siliceous organisms present in the 
gathering, I took a quantity in the rough state and, after break- 
ing it down by Potassa, acted on it with boiling Hydrogen 
Nitrate. Thus I found that I had good representatives of all 
the gathering contained. Some specimens, however, are not 
fracenly cleaned by boiling, even for a considerable length 
of time in strong Hydrogen Nitrate. To such I add either 
Hydrogen Chloride alone or a few grains of finely-pulverized 
Potassium Di Chromate. In this way, and after thoroughly 
washing with pure water I have been enabled to obtain 
extremely beautiful specimens of Diatomacew, Radiolaria and 
other siliceous organisms in a good condition for studying them. 
This I am engaged upon at the present time and intend before 
long to lay the results before the Lyceum. 
Mr. S. F. Mackie made some remarks, illustrated by means 
of diagrams, upon the construction of ancient ships; showing 
that the principles of construction and to a great extent of 
managing sailing vessels has remained essentially the same 
from the earliest dates up to the present time. 
