16 Sparry Acid. [feook VI; 



effect in carrying off the colouring particles which 

 are detached from the cloth by the action of the 

 oxygen. 



When ore or two parts of pale concentrated nitrous 

 acid are mixed with four of fuming muriatic acid, an 

 effervefcence foon takes place, and oxygenated mu- 

 riatic acid is produced 5 at the fame time that the 

 mixture becomes of a red colour. The mixed acid 

 is called aqua regia, which has the property of diffoiv- 

 ing gold. 



The SPARRY or fiuor acid was difcovered by Mr. 

 Scheele-, and takes its name from the fubflance from 

 which it is obtained, arid which is commonly known 

 in England under the name of Derbymire fpar. This 

 acid when pure aifumes the form of gas. In this 

 ftate it is heavier than atmofpheric air, extingvMmes 

 flame, and deftroys animal life ; it has a penetrating 

 fmell, like that of marine acid, but more powerful j 

 and its caufticity is fuch that it almoft inftantly cor- 

 rodes the fkin. Heat dilates it, without producing 

 any other change. The addition of atmofpherical air" 

 has the effect of producing with it a white vapour, 

 which is more or lefs abundant, in proportion as the 

 atmofphere contains more or lefs of humidity. 



If vitriolic acid is poured on the Derbyfhire fpar* 

 which is a combination of this peculiar acid with 

 calcareous earth, and a gentle heat applied, the acid 

 is difengagcd in an aerial form. It readily combines 

 with water, and therefore the recipient mould be half 

 filled with that fluid. The firft experiments which 

 were made of the diftillation of this acid in glafs vef- 

 fels, were attended with a finking appearance, which 

 required confiderable acutenefs for its explanation". 

 It was obferved that as foon as the acid gas reached 

 the furface of the water, a quantity of earthy matter 



was 



