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the more volatile parts being sent off in the 

 explosion, gunpowder being a composition of 

 nitre (nitrat of potass), sulphur, and charcoal. 

 The oxygen of the nitre uniting with the char- 

 coal, forms carbonic acid gas, the nitrogen of 

 the nitre is disengaged, which all go off in an 

 jiL : rial form on the explosion ; and the fixed part, 

 the potass, uniting with the sulphur, forms a 

 sulphuret of potass. If the alkali and the sul- 

 phur are mixed together in a dry form, and a 

 sufficient heat is applied, when they begin to 

 melt they unite with effervescence, and the pro- 

 duce (sulphuret of potass) was formerly called 

 hspar sulphuris (liver of sulphur), from its re- 

 semblance to the liver of animals. Soda will 

 form a similar compound. 



The sulphuric acid may be obtained from sul- 

 phur, by spreading the sulphur on a plate, and 

 covering it with a glass bell, the inside of which 

 is wetted with the dew of hot water ; the sulphur 

 being inflamed, the vapour arising attaches itself 

 to the dew. This process has been already ex- 

 plained. 



It has been supposed that the sulphuric acid 

 exists in the air ; the only argument for which 

 opinion is, that on exposing an alkaline salt to 

 the air it is said to contract a quantity of the acid. 

 But there are no accurate and well-attested ex- 

 periments to prove this, but rather the contrary. 

 Neumann, the most curious and exact chemist of 

 his age, did not find sulphuric acid in rain and 



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