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equilibrium lunar tide in a solid glass globe (without mutual 
gravitation) of the same size as the earth is about five feet. 
Hence, from the phenomena of the actual tides of the ocean, 
it follows that the earth, as a whole, is more rigid than glass. 
The observations of Mallet, with experimental earthquakes, 
show that the earth’s crust is many times less rigid than glass. 
Hence Professor Thomson infers that the earth, as a whole, 
is many times more rigid than the rocks and strata on its 
surface. 
Dr. Crace Calvert stated that he wished to draw the 
attention of the manufacturing chemists of this district to a 
very simple and rapid method which had been devised by the 
eminent chemist M. Pelouze, Master of the Paris Mint, for 
determining the amount of sulphur existing in pyrites. He 
(Dr. Calvert) was induced to do so, believing that any pro- 
cess which would simplify the long and troublesome operations 
now followed to ascertain the value of this mineral would be 
useful to many members now present at this meeting. The 
process consists in mixing intimately together one part of 
pyrites, thoroughly pulverised in an agate mortar, with five 
parts of carbonate of soda, seven parts of chlorate of potass, 
and five parts of chloride of sodium, and placing the whole in 
an iron spoon, which is gradually carried to a dull red heat. 
The mass, when cold, is first washed with cold water and 
then with boiling water, until the whole of the soluble matter 
is removed ; and this solution is tested with a standard solution 
of sulphuric acid. As 100 grains of carbonate of soda requires 
92*45 of monohydrated sulphuric acid, or S O 3 H O, it follows 
that the quantity of soda in the carbonate of soda employed 
