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will decrease in proportion to the quantity of sulphur from the 
pyrites converted into sulphuric acid, which will have 
neutralised a corresponding quantity of the soda in the 
carbonate. 
This mode of assaying is so simple, that the Author states 
that he can determine, within one or one and a half per cent, 
the value of a sample of pyrites, in the space of an hour’s 
time. 
M. Pelouze also states that by employing the following 
proportions of the same materials, the manufacturer can deter- 
mine the amount of sulphur in burnt pyrites. Five parts of 
the latter substance are mixed intimately with five parts of 
pure carbonate of soda and five parts of chlorate of potash. 
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