B L E 



it entered the receiver, became then the oLi-,e\ of his atten- 

 tion ; and for this purpofe he found it was necelTary to keep 

 the lime floating, or diffufcd tlirough the fluid, which he 

 Succeeded in accoinplifliing by two diflVrcnt methods ; one 

 of which was by increafing the fpccilic gravity of the water 

 in the receiver, by the addition of common fait, and thus re- 

 tarding the lime from fubfiding ; tiie other mode was by 

 conftant agitation of the lime in the water in the receiver, to 

 keep the lime diffnfed through the fluid, during the time the 

 oxygenated muriatic gas was introduced ; and by t'lis means 

 he fucceeded in uniting and retaining a much greater quan- 

 tity of gas with the mixture, than by any method heretofore 

 ufed, and without the addition of any afli^s or alkaline 

 fub Glances. 



A very material advantage was gained by this difcovery ; 

 Tiamely, that it uniformiy afforded fecurity to the dyed co- 

 lours in a fuperior degree to the alkaline ley. 



It is well known, that in the alkali of commerce, fuch as 

 pot-afli or pearl-afli, a large and very irregular proporrum 

 of neutral falts is intermixed, which are foluble along with 

 the alkali in water, thereby fo far contaminating the ley, 

 that the bleacher is always uncertain what quantity of pure 

 and aftive alkali it contains. In bucking or boiling cotton 

 poods, the detriment from thefe neutral falls is not fo great, 

 as a repetition of the procefs may compenfate for thofe ad- 

 mixtures in the ley : but in the bleaching liquor formed by 

 the mixture of the oxygenated muriatic gas with fuch ley, 

 if there is a deficiency of alkali, the uucombined oxymuriatic 

 acid immediately attacks the dyed colours of the goods, and 

 difcharges them , and thus confiderable damage frequently 

 occurs before the real origin of the evil is afcertained and 

 correfted. Ti>e bleacher is kept in a conftant ftate of alarm 

 refpcfting the quality of the alhes he makes ufe of, befides 

 the great colt of their purchafe. In ufing lime for the fame 

 purpofe, the exptnce is a mere trifle ; what is not combined 

 ■with the oxymuriatic acid precipitates, after the agitation 

 is over, leaving a pure liquor free from ail uncombined 

 acid. 



Simple as the combination of the lime with the oxygen- 

 ated muriatic acid may now appear, yet it was a long time 

 attempted in vain ; but this, pcrhap", will not be fo much a 

 inatter of furprize, when we refleft that the French chemitts, 

 vhofe opinions were regarded generally as law by the com- 

 inon bleachers, and whofe treatifes on the fubj.-ck of bleach- 

 inof were almofl; the only nccounts publiihed, confidered 

 lime as no further ufeful in lleaching, than in abforbing the 

 carbonic acid or fixed air ufually combined vs-ith alkalies or 

 arties ; and thus rendering the alkaline ley more difpofed to 

 tjnite with the oxygenated muriatic gas, when cxpoftd to its 

 contaft in the receiver, to form, as it is called, the liquor de 

 Javelle ; or, when intended for life as a mere alkahne ley, to 

 render its aClion more powerful on the oily particles in the 

 vegetable fibre, on a fimilar principle to the formation of 

 foap. 



An excellent treatife on the fubjeft of bleaching, in the 

 Englifh language, viz. " The Report on Expci-iments made 

 by order of the right honourable the truftees of the linen 

 and hempen manufaftures, to afcertain the comparative me- 

 rits of fpecimens of oxygenated muriatic bleaching liquids," 

 publifhed at Dublin in the year 1791, in claim of a bounty 

 ofi^ered by the truftees, appears to convey no further know- 

 ledge of the ufe of lime in bleaching at that time, than in 

 promoting the feparation of the carb nic acid from the leys, 

 whether the^' were afterwards to be ufed alone, or in the 

 ■preparation of the oxygenated muriatic acid. Mr. Rofe's 

 experiments in this report contain, however, much ufeful 

 information, which ■wc ftiall further notice. 



B L E 



The fimpllcity of Mr. Tcnnant's invention of retaining « 

 greater quantity of the oxvgeuated muriatic gas, by agitation 

 of a fufflciency'of lime in the water of the receiver, fliould 

 be no derogation to its real merit. In fubflituting lime for 

 pot-alh, an article, not only of foreign produce, but cxpeii. 

 five, he has benefited this country to an extent almolt be- 

 yond conception ; it having been pi'oved upon oath, that by 

 the ufe of Mr. Tennant's procefs, the confuniption of afhes 

 at a fingle blcaching-green has been reduced three thoufand 

 pounds iterling in value in one year. A patent for Mr. Te- 

 nant's invention was granted him in the year 1798 ; but, as 

 frequently happens in patent caufcs, on a late trial ol its va- 

 lidity, fome circumftances arofe, from which the jury 

 thought themfclves jiiftified in reverfing the patent ; %ve 

 have therefore, with confiderable pains, collected for the 

 public benefit an account of his procefs, and the moft ap- 

 proved mode of putting it in practice, either on a fmall or 

 an extenfive fcale, as will be fccu by a reference to Plale I, 

 of Bleaching hereafter defcribcd. 



Mr. Tennant's me'hod of ufing calcareous earth for neu- 

 tralizing the muriatic acid gas, and forming the oxy-muriat 

 of lime employed in bleaching, is as follows ; viz. — fn a re- 

 ceiver capable of containing one hundred a'^d forty gallons 

 wine meafure, diflolve thirty pounds of common fait, which 

 appear ufeful only in giving an additional degree of fpecific 

 gravity to the water, and by that means making it eafier to 

 keep the lime to be afterwards addtd, in fulpe-ifion ; when 

 this fait is dilfolved, add fixty pounds of finely powdered 

 quicklime, and into the retort of the apparatus put thirty 

 pounds of powdered manganefe, mixed up with thirty pounds 

 of common fait, upon which pour thirty pounds of ful- 

 phuric acid (oil of vitriol), previoufly diluted witii its bulk 

 of water, and the ufual precaution of luting the veffel being 

 taken, proceed to difti'.lation. When the gas begins to ap- 

 pear, the agitation of the lime and water in the receiver 

 muil commence, which fliould be continued by means of a 

 wooden paddle or rake, or fimilar contrivance, without in- 

 termiflion, until the materials in the retort, after heat being 

 employed as ufual, will not yield any more oxygenated mu- 

 riatic acid gas. Then the whole Ihould be allowed to re- 

 main at reft for two or three hours, when the clear liquor ia 

 the receiver may be drawn off for ule, and mixed with water 

 in fuch proportions as may be found neceffary, previous to 

 the immefion of the goods to be bleached. 



The principal point of attention in preparing this oxygen- 

 ated muriat of lime is, to obtain a complete dilfufion of the 

 lime through the mixture, or a mechanical fufpenfion of it irj 

 the water diiri;!g the operation, fo that every particle of the 

 lime may, by agitation, be expoftd to the adlion of the gas, 

 in (lead of merely its upptr furface, as had been formerly 

 pradifed. By the prefent means, the oxygenated muriatic 

 acid gas is abforbed with eafe, and meets with a fufficient 

 quantity of lime to produce a ftrong folution of oxvgenated 

 munat of lime, without any uncombined oxvgenated muriatic 

 acid ; a thing w'.iich could not be otherwife effefted. The 

 additionof the comm.on fait in the receiver may even be omit- 

 ted, without prejudice, if the agitation of the lime be well 

 ma aged. 



Plate ^•Jig- 2. of Bleaching, (hews a longitudinal fcflion of 

 a method, which has been praclifed in Ireland for diftilla- 

 tion of the oxygenated muriatic acid, and the formation of 

 the oxygenated muriat of lime, a, the alh-hole ; i, the fire 

 under the iron pot or veffel ; c, the aperture through which 

 it is fupplied with coals ; d, the entrance to the afli hole, 

 which may bt provided with a ftopper of burnt clay, or 

 earthen ware, to regulate the draught of the fire, by means 

 cf the handle fhewu by dotted lines ; f, a caft-iron pot or 



