as well to examine analyses of sea-water and cement. The water
of the Irish Channel is composed of


Sodium chloride.................... 2.6439 per cent.
Magnesium chloride................. 0.3150 " "
Magnesium sulphate................. 0.2066 " "
Calcium sulphate................... 0.1331 " "
Potassium chloride................. 0.0746 " "
Magnesium bromide.................. 0.0070 " "
Calcium carbonate.................. 0.0047 " "
Iron carbonate..................... 0.0005 " "
Magnesium nitrate.................. 0.0002 " "
Lithium chloride................... Traces.
Ammonium chloride.................. Traces.
Silica chloride.................... Traces.
Water.............................. 96.6144
--------
100.0000


An average analysis of a Thames cement may be taken to be as
follows:--


Silica................................ 23.54 per cent.
Insoluble residue (sand, clay,
etc.)............................ 0.40 "
Alumina and ferric oxide............... 9.86 "
Lime.................................. 62.08 "