Mr. Henrfs Confideratiom, C^c. 403 



fore conclude that the amount of this fait, con- 

 tained in fix gallons of the firft barilla liquor, the 

 quantity added to thirty pounds of alum, does not 

 exceed one pound and half. Now as 100 parts 

 of alum contain 3S of vitriolic acid, thefe will 

 require for their faturation, 37 of aerated 

 mineral alkali j fo 30 parts of alum containing 

 II : 4 of that acid, thefe will require for their 

 faturation 11 : i of the fame alkali. Whereas 

 the quantity employed amounts only to 1:5; 

 or rather more than f of the quantity requifite 

 for the neutralization of the acid. And as 

 a fuperabundant quantity of the precipitant, 

 above what is neceflfary to the faturation of the 

 acid, is neceffary before re-folution of the pre- 

 cipitate can take place, we have in this cafe 

 no reafon to expeft it. 



2. The quantity of alkali employed is not 

 fuperior to that ufed in the aluming in other 

 proceffes for dying with madder.* 



3. The alkali, Being aerated, is in the 

 moft unfavourable ftate for rediflblving the 

 aluminous earth ; and 



4. The re-folution of the aluminous earth 

 takes place only fo long as any of the fuper- 

 abundant vitriolic acid remains unneutralifed ; 

 except the addition of alkali be continued, 

 after the precipitation of the aluminous earth is 



• i or i of the alum. 



D d a whollv 



