186 On Smelting of Lead. 



tire state with silk, wool, cotton, and thread ; that this 

 compound retains its acid but f'ceblv, and loses a portion of 

 it bv simple exposure to the air ; and that it is then changed 

 into acid acetate of alumina, which is carried off by water, 

 and into alumina which remains upon the stuffs. 



4. That alum and tartar are not decomposed, but that 

 the solubility of the latter is increased by the mixture ; and 

 that in impregnaliug wools either with tartar, or alum and 

 tartar; ihe tartar aJone is decomposed, that tlie tartarous 

 acid and alum combine with the stuff, and lartrite of 

 potass remains in the bath. 



5. That the most powerfr.l acids have the property, when 

 combined wiih wool, of fixing the colquriug matters, a 

 property possessed in a high degree by the acid tartrite of 

 alunjina. 



6. That alum and tartar cannot be employed indifferently 

 for all colours, and that their proportions must depend 

 wpon the nature of the colouring matter; that the time of 

 aluniing should not be more than two hours, and that the 

 exposure of the stuffs in a moist place, after the mordants 

 are applied, is of no utility in augmenting the intensity of 

 their colour. 



7. That highly oxidized tartrite of tin, dissolved in mu- 

 riatic acid, may supply the place of cream of tartar and the 

 solution of tin in dyeing scarlet. 



8. Lastly, that these experiments furnish some useful 

 hints for combining mordants with the stuffs to be dyed, 

 and for improving several of the processes of dyeing. 



To complete these researches relative to the action of 

 mordants, it would without doubt be necessary to deter- 

 mine, in the most accurate manner, the changes produced 

 in these combinations hv the colouring matters, when ap- 

 ])lied to the different stuffs : but these experiments, which 

 we have already commenced, will form the subject of a se- 

 cond Memoir, to be hereafter presented to the Class. 



XXVII. An yJccouiit of I he Smelting of Lead, Bij Mr, 

 John Sadlek. 



[CoiitimicJ from vol. xxxviii. p. 37G.] 



^1^ Cupola Smelting*. 



-L HE process of smelting here described, appears to be 

 defective in some points, which I will take the liberty to 

 jiieution, and at the same time suggest the means of im- 



* Sec an accoiiiU-of tlie present state of this art, in Mr. Farey's Derbyshire 

 Report, vol. i. p- 380". — Editor. 



improvement ; 



