854 ^''•'^ ^fi of Sulphuret of Lime in Bleaching. 



asi important obfervation of Mr. Kirwan, that faline hepars, or tlie comblnatioi> of nn alkali 

 with fulphur, might, from its detergent properties, be advantageoufly euiployed in bleaching 

 as a fubftitute for mere alkali, by an obvious analogy I was led to cxpc<£t a fimilar cfFeiSt 

 from calcareous hepar, or, more properly fpeaking, fuiphuret of lime, being a combination 

 of lime and fulphur. 



In thefe expedlations I was not difappointed ; but at that time (about three jrears fince) I 

 contented myfelf (rather through neceffity ; for large cities are very unfavourable to experi- 

 ments of bleaching, by expofure to atmofphere) with pointing it out to fome of the principal 

 bleachers from the north then in town, earnellly recommc;iding it to them to give it a fair 

 trial with and without potaOi. Since that time, alkaline falts have becon~.c progreiBvely dearer, 

 and in confequence of a late propofal of fubftituting lime for potafn, in coiidenfing the oxy- 

 tnuriated gas, I was infligated to refume the fubje£l, and make further and more varied trials. 

 The refult of which has been, that the ufe of the fuiphuret of lime may be moll advantageoufly 

 combined with that of the oxymuriated lime, and that thus cloth may be perfeiSlly whitened 

 without the ufe of a particle of alkali. This, then, alone would feem to give it a decided pre- 

 ference over the methods at prefent in ufe, while at the fame time it poffeires peculiar advan- 

 tages, and is exempt from the principal objections to which other fubjlituies are liable; for 

 firfl:, quicklime and fulphur, the materials of which the cakareoui hepar confifts, are both 

 articles of trivial expence, efpecially as the latter enters but fparingly into the comjvofitioa; 

 2dly, their combination is efFefted in the eafieft and moft expeditious manner poffible, and 

 perfeclly level with the capacity of the mcaneft workman ; 3dly, as the manner of its appli- 

 cation is by fteeping the cloth in it cold, the faving of fuel is a matter of great magnitude} 

 and laflly, there is no danger to be apprehended in the ufe of it from the unfkilfulnefs or 

 negligence of the workmen, as it appears to be incapable of injuring the texture of the cluth. 



The fuiphuret of lime is prepared in the manner following : Sulphur or brimflone, in fine 

 powder, four pounds ; lime, well flacked and fifted, twenty pounds ; water, fixteen gallons : 

 thefe are all to be well mixed and boiled for about half an hour in an iron vefTel, ftirring 

 ~ them brifkly from time to time. Soon after the agitation of boiling is over, the folution of 

 the fuiphuret of lime clears, and may be drawn ofF free from the infoiuble matter, which is 

 confiderable, and which refls upon the bottom of the boiler *. The liquor in this ftate is 

 pretty nearly of the colour of frhall-beer, but not quite fo tranfparent. 



Sixteen gallons of frefh water are afterwards to be poured upon the infoiuble dregs in the 

 fcoiier, in order to feparate the whole of the fuiphuret from them. When this clears (being 

 previoufly well agitated), it is alfo to be drawn ofF, and mixed with the firft liquor : to thefe 

 again thirty-three gallons more of water may be added, which will reduce the liquor to a 

 proper ftandard for fleeping the cloth. 



• Alibough litne is one of th« conftitutnt principles of the fulphurtl, yet being fo intimately united to the 

 fulphur, it has no longer the property of lime ; upon the fame principle ihstjul/bitric acid in fulphate of potaih 

 has not the property of that acid, 



pere 



