B L E 



an i3ea tliat was genei-ally maintained by the cliemUls, but 

 «ontradiifted by the bleachers, whofe experience taught them, 

 that though the acid thus combined whitened with fome- 

 ■what lefs rapidity, yet it was not eventually in an inferior 

 extent ; and the advantages of preferving the colours dyed in 

 the yarn, compelled them to have recourfe to the expenlive 

 addition of pot-a(hes, in preference to M. Berthollet's 

 anode. 



Here we (hall obferve, that, according to the doflrine of 

 the modern chemifts, the oxygenated muilatic acid bleaches 

 in confequence of yielding to the colouring matter of the 

 scloth that oxygen which, in the diftillation, the acid ab- 

 forbed from the manganefe; orj in the language of Stahl 

 and Becher, that the dephlogifticated marine acid abforbed 

 the colouring matter from the cloth, and was reftored to its 

 ■original ftate of common marine acid, bv regaining that 

 yhlogifton which it had, in its preparation, yielded to the 

 inanganefe. 



In the mixture of an alkali with the acid, we have noticed 

 that the bad confcqucnces arifing from its volatility have 

 foeen corrected, and the requifite protedlion afforded to dyed 

 •colours, yet Hill that its power of whiceiiing cloth was eot 

 •dirainifhed, nor much more time taken up by the operation ; 

 Tct, in part from deference to M. Berthollet's opinion, and 

 in part owing to the expence of the alkali, other means to 

 produce the effect were attempted. 



One of the firil of thefc, praftifed by the bleachers of 

 cotton-hofe, at Nottingham, was to receive tlic dephlogifti- 

 cated muriatic gas into a fmall air-tight chamber, in the 

 upper part of which the goods wei-e fufpended from a 

 frame, whilft at feme diflance below was water, fometimes 

 impregnated with ley of pot-afli, and fomecimes with lime- 

 water, or water mixed with lirne^ The gas was introduced 

 betwixt the fluid and the goods, amongit which it afcended 

 find mixed ; at the fame tune, by occafionally immtrfing 

 the goods in the fluid below, it was fought to modify the 

 4i6lion of the acid. This was effefted by means of a pole, 

 or long lever, connefted with the frame on which the goods 

 wrere fufpended, the centre of which pole moved on a Iwivel 

 fixed in a hole in the partition, occahonally liopped with 

 day, and enabled a perlon to let the goods down into the 

 fluid, not always however without inconvenience, which oc- 

 ■Cafioned it the name of the Bedlam Precefi, 



Refpeiling the above procefs it muft. be obferved, that 

 the acid is much more powerful or adtive in the ftate of gas 

 than in any other way ; and though the occafional immerhon 

 of the goods into the fluid below, contcted in fome degree 

 ^jts violent effecls, yet the dyed colours difappeared move 

 rapidly in this than in any other procefs, and tlie fabric 

 kfelf was fometimes injured. 



The next procefs attempted by the bleachers, was to put 

 into the receiver, filled with water, a quantity of pulverized 

 lime, then the goods themfelves, and the whole agitated 

 ■during the admiffion of the gas ; the confequence of wl-ich 

 ■was, that the goods thus mixed with lime were partially 

 coated with it ; and this coating being unequal, the ailion 

 of the acid upon it v<zs irregular, leaving at the fame time 

 the parts uncoated to receive the whole ac^tion of the bleach- 

 ing powers ; hence inequality of bleaching enfucd, and an 

 inlurmountable difficulty in preferving the dyed colours 

 of the goods to be bleached. 



Having noticed the imperfetlions of the two lafl proceffes, 

 we fhall obferve that hme-water, or a pur ■ chemical folLition 

 of lime in water, has been fometimes fubilituted inftead of a 

 ■solution of alkalies in the receiver, but was not, when ufed 

 in that manner, found to anfwer To well as the alkahjie fo 

 lution. 



Vol. IV, 



B L E 



That lime-water conld produce no valuable effeft beyond 

 what was derived from M. Berthollet's mode, or from Am- 

 ple water, muft be evident, when it is confidered that water 

 can diffolve no more than ^^s-'h part of its weight of lime, 

 a quantity wholly infignificant in neutralizing the oxygenated 

 muriatic acid for the purpofe of the bleacher; nor could pul- 

 verized hme, merely thrown into the water of the receiver, 

 ferve a better purpofe, fince, from its being fpecifically 

 heavier than the water, all beyond the quantity in chemical 

 folution fubfided and remained nearly ufelefs at the bottom 

 ot the receiver. 



It has been already mentioned, in noticing the application 

 of alkaline leys in bleaching, that the more intelligent 

 bleachers, in preparing their adi-leys, made ufe of quicklime 

 to augment the power of the alkali, when fuch alkali was in 

 a mild ftate, or, in other words, combined with lixed 

 air, or, as it is now termed, carbonic acid ; the at- 

 traction of cauftic lime for the carbonic acid being ftronger 

 than that of adies. Hence, on cauftic lime being thrown 

 into mild afti-ley, the carbonic acid, by which the afhe* 

 Wire rendc"ed mild, abandons the alkah to combine witk 

 the lime, leaving the afnes in their cauftic ftate. 



But, although the attraction of carbonic acid is ftronger 

 for lime than for alkali, the contrary is the cafe with the oxy- 

 genated muriatic acid, as it abandons lime to combine with 

 alhes, leaving the lime to precipitate. 



This obfervation is made in order to guard the ignorant 

 bleacher from millakes, who, from having mixed lin^e witk 

 his afli-iey in the receiver, in the preparation of the oxygen- 

 ated marine acid, may fuppofe it afts in a fimilar manner ; 

 but not a particle of lime is acted upon by the acid, whiltl 

 alhes remain to combine with it ; the only effeft of the linve 

 there, being toabftract from the alhes any fixed air they may 

 contain, and fo difpofe the alkah to abforb more of the oxy- 

 genated muriatic acid, 



Befides the proceffes above mentioned, the bleachers at- 

 tempted to unite the oxygenated muriatic acid with clay ; but 

 as the clay has fcarcely any affinity with it, the liquor thu« 

 made was httle, if at all, fuperior to that of M. Ber.hoilet. 



Such were the attempts made from the year 1786; and 

 the oxygenated muriatic acid combined with pot-aih was ia 

 general ufc by the bleacher until 179S, when Mr. Tcnnant, 

 of Glafgoiv, by a well-condufted feries of experiments, formed 

 what may not improperly 'be called a new aera in bleaching. 



Mr. Tennant, having feen fo long a period clapfe without 

 any material improvement in bleaching, and the alkali, 

 tliough an expenfive ingredient, regarded by the bleacher a* 

 an indifpenfible article to uiiite witii the oxygenated muria- 

 tic ac'd in the receiver, made fome trials with the earthg 

 ftrontites and barytes, and with fuccefs. Their fohibility 

 in water enabled iiim to combine them with a fufficient 

 quantity of oxygenated muriatic acid to ferve the purpofe { 

 but the fcarcity of ftrontites, au'l the difficulty of feparatin^ 

 barytes from the vitriolic acid, with v/hich it is ufuallv found 

 in combination, rendered thefe difcoveries rather objetts of 

 curiofity than ufe. 



Mr. Tennant had previoudy made eicperiments to combine 

 the oxygenated muristic acid with lime and lime-water, ia 

 the modes above-mentioned, but found they were not ade- 

 <juate to tlie purpofes intended ; the lim.e in general remain, 

 ing at the bottom of the receiver tuicorabincd with the gas, 

 which was the neceHary confequence of the lime being fpeci- 

 fically heavier than the water, and the gas ranch ligiiter ; 

 the water, by its interpofition betwixt the two fubftauces 

 which ought to be combined, namely the oxygenated muri- 

 atic gas and the hme, preventing their union. To brinj 

 the pulverized lime mx/i contact with tlie gas as quick^ a» 

 «K it 



