The Vfe of Sulphuret of Lime in Bleaching. 2^^ 



^ Here we have (an allowance being made for evaporation, and for the quantity retained in 

 the dregs) fixty gallons of liquor from four pounds of brimftone. 



Although fulphur itfelf is not in any fenfible degree folublc in water, and lime but very 

 fparingly fo, water di'ffolving but about one feven hundredth part of its weight of lime, yet 

 the fulphuret of lime is highly foluble *. 



When the linen is freed from the weaver's drefling, it is to be fteeped in the folution of 

 fulphuret of lime (prepared as above) for about twelve or eighteen hours, then taken 

 out and very well waflied ; when dry, it is to be fteepeJ in the oxymuriate of lime for 

 twelve or fourteen hours, and then wafhed and dried. This procefs is to be repeated fix 

 times ; that is, fix alternate immerfions in each liquor, which I found fufficient to whiten 

 the linen. 



When I fubmitted the linen to fix boilings in potafti, and to fix immerfions in the oxygenat- 

 ed liquor, it was not better bleached than the above. 



The three firft boilings in potafh, it is true, produced a fomewhat better efFedl than as 

 many fteeps in the fulphuret; but towards the conclufion, that is, when the linen was 

 bleached, the fmalleft difference was not obfervable as to colour. The linen bleached 

 with the potalh was thinner, or more impoveriftied, than that treated with fulphuret ; and 

 the latter ftood the teft of boiling with foap much better than the former, although it did ac- 

 quire a flight yellowifh tinge, which I fhould fuppofe a week's, or at moft a fortnight's, grafs, 

 as they term it, would remove. 



Icontraftod the effects of hot and cold fulphuret in various temperatures, and although the 

 difference appeared in favour of the hot liquor, yet it was fo trifling as not to deferve con- 

 fideration, or the expenditure of the fmalleft quantity of fuel. 



When I fteeped the linen in the fulphuret firlV, and afterwards boiled it in potafh, and 

 then immerfedit once in the oxygenated liquor, a better effe£l was produced than from two 

 previous boilings in potafh, or from two flceps in the fulphuret; fo that the two fubflanccs 

 feem to co-operate v\ ith each other. 



Indeed, from what I have feen, two fucceilive fleeps in frefh fulphuret previous to the im- 

 merfion in the oxygenated liquor, feemed to afford very little b«tter cffedt than a fingle one, 

 which is not the cafe with refpeft to potalh. 



It was obfervable, that the cloth was invariablv thicker, or more fwelled, coming out of 

 the fulphuret, than after being boiled in potaih, and remained fo when even walhed and 

 dried. 



It appears to me that the fulphuret opens the fibres of the linen more fpeedily and better 

 than the latter, by foftening and fwelling, rather than by diflTolving the refinous or colouring 

 matter. This accounts for the better effedt of potalh upon the linen when previoufly 

 fteeped in the fulphuret, than wiien ufed by itfelf. 



• When the above proportion of lime and fulphur is boiled with only twelve gallons of water, the ful'- 

 ,^uret partly cryftalliies upon cooling, and when once cryftalliied, it is not eafy of folution. 



I- 1 2 i Probably 



