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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. 



