B L E 



B L E 



Sours; at the enci of wlWch time, any common fait it 

 contains will be found ciyltallized in regular cubes at the 

 bottom of the vcdel ; pour etf the clear liquor, and repeat 

 the procefs, till no more cubic cryftals are produced. If it 

 is defired to be very accurate in the analyfis, before the com- 

 mon fait (muriate of foda) thus procured is weighed, fome 

 muriatic acid may be pom;d upon it, in order to tiike up 

 any of the pure pot-afn which may have adhered during^ its 

 cryftallization. The muriatic acid, with fuch of the alkali 

 as it has difToWed, may be then drained off and thrown away, 

 and the muriate of foda dried and weighed. 



The fiim of the impurities being then fubtraftcd from the 

 weight of the fpecimen, the quantity of the pure pot-a(h is 

 afcertained. 



To ^ne^v whtit quantity of mere alkali is contained in 

 toolb. avoirdupois of feveral different alkaline falts examined 

 by Mr. Kirwan, we (hall add the following table, publiflied 

 hy him in the Iridi Tranfa ^tions, in 1789. 



One hundred Pounds. M-neral AiJcali. 



Cryflallized foda - yielded - ciolbs. 

 Sweet Barilla - - - 24 



Mealy 's cunnamara kelp - - 5-4.37 



Do. defulphurated by fixed air - - 4-457 

 Strangford kelp . _ - 1.25 



Ore hundred F'ounds. Vegetable Alkali. 



Dantzic pcarlafli - yielded - dj.^jlbs^ 



Cldike's refined a(h ~. . . 26.875 



Caf.iup .... 19.3 7<5 



Common raw Irifli weed-ath - 1.666 



Do. flightly calcined - - 4.666 



It is much to be regretted that, confidering the immenfe 

 qumtities of pure marine alkali which could be procured at 

 a cheap rate from the Eaft Indies, that fo Tittle attention 

 fhould be paid by the Eaft India company to an article 

 which would be fo profitable abrar.ch of commerce to them^ 

 and prevent a confider^ble fum being pnid to other natior.s.- 

 The mineral alkali procured from the Eall Indies, is mucb 

 purer than what is obtained from Barilla ; and a prepara- 

 tion exaftly Cmilar in appearance and qviahty to the Alicant 

 Barilla, may be made with great advantage to the manufac. 

 turer, from a mi.vturt of the Eaft India mineral alkali with the 

 common Scotch kelp,, for the purpofes of the bleacher,- the 

 foap maker, or the Turkey-red dyer. To fliew the import, 

 ance of this objeft, the following table of the in^poits into 

 Great Eritaiu are annexed for feven years. 



Barilla. Pot-ACies. Pearl-Afhes. 



1796 86.723 cwt.. 62.829 CWt. 45.290 CWtf 



1797 51.105 57-826 36.674 



1798 123.990 81.4S2 60.691 



1799 146.163 77-24<5 51-79- 



1800 175.629. 135.400 45.161 



1801 63.210 9°-5^3. 54-8J5 



1802 151.796 48.054: 64.2S8 

 When it is confidered that 20 pounds of the mineral alkali 

 brought from India in a powdery ftate, as it ufually is, will, 

 by mere filution in water, yield icolbs.. of the cryftalliztd 

 foda fold in the (hops, it will be feen, that the purchafe of 

 the mineral alkali from the Eaft India company, will be an 

 objcft well defcrving the attention of the bleachers and fcap- 

 boilers ; and far preferable to the ufe of Spanilh kelp or 

 Barilla. 



Mr. Kirwan, by means of muriatic acid, precipitated the 

 colouring matter from an alkaline ley, faturated with the 

 co'ouring matter of linen yam, and found it to poffefs the 

 following properties. When fuffered to dry for fome time 

 caa filter, it alTuaicd a dark green colour^ and fdtfgme'A'hat 



clammy, like rnoill clay. His obfervations in the Irifh 

 Tranfadlions for 1789, are as follow : 



*' I took, fays he, a fmall portion of it, arid added to it 60 

 times its weight of boiling water, but not a particle of it was 

 diffolved. The remainder I dried in a fand-heat ; it then 

 alfumcd a (hiaing black colour; became more brittle, but 

 internally remained of a greenilh yellow, and weighed one 

 ounce and a half." 



" By treating eight quarts more of the faturated ley in 

 the fame manner, I obtained a further quantity of the 

 grceni(h depofic, on which I made the following experiments : 



ift. Having digellcd a portion of it in rectifiL-d fpirits of 

 wine, it comm.unicated to it a rcddifli hue, and was, in a 

 great nieafure, diffolved ; but by the affufion of d;ftilled 

 water, the foiution became niiiky, and a white depoCt was 

 gradually formed ; the black matter diffolved in the fame 

 manner. 



2d. Neither th,e green nor the black matter was foluble in 

 oil of turpentine or linfeed oil, by a long cor.tinued digeftion. 



3d. The black matter being placed on a red hot iron, 

 burned with a yellow flame and black fmoke, leaving a 

 coaly refiduum. 



4th. The green mattjr being put into the vitriolic, marine 

 and nitrous acids, com.municated a brov/nifh tinge to the two 

 former, and a greenifh to the latter, but did not feem at all 

 diininifhed, 



" Hence, it appears,.that the matter extrafted by alkiliea 

 fiom hnen yarn,, is a peculiar fort of refin, different froiti 

 pure refins only bv its infolubility in effcntial oils, and in 

 this refpeft refembling lacs. I now proceded to .-xamine 

 the powers of the different alkalies on this fubllance, eight 

 grains of it being digefted in a folutio:; of cryiiallized mi- 

 neral alkali, faturated in the temperature of 62°, inftantly 

 communicated to the foiution a dark brovi'n colour ; two 

 ireafnres (each of which would contain eleven pennyweights 

 of water), did not entirely diffolve thij fubllance. Two 

 meafures of the mild vegetable alkali diffolved the whole." 



" One meafure of cauftic mineral alkali, whofe fpecific 

 gravity was 1.053, diffolved nearly the wiiole, leaving only 

 a white refiduum." 



" One mealure of cauftic vegetable alkali, whofe fpecific 

 gravity was 1.0.39, diffUved the whole." 



" One m.eafure of liver of fulphur, whofe fpecific gravity 

 was 1.17c, diffolved the whole." 



" One meafure of cauftic volatile alkali diffolved alfo a 

 portion of this matter." 



The colouring matter of cotton is much more foluble in 

 alkali, than that of linen : hence the greater facility with 

 which cotton is bleached. 



The theory of bleaching vegetable matter, as we have 

 before obfervcd to have been defcribed by Mr. Delaval, 

 depends on removing the colouring matters, whether natural 

 or accidental, which cover their folid fibrons parts, which 

 are the only parts endued with a rcfletlive power. 



Raw cotton or linen, boiled in a a diluted foiution of 

 cauftic alkali, gives to the liquor a deep brown colour, and 

 deftroys its caufticity ; and frc(h portions of clear ley ap- 

 plied a fecond or third time, v.'ill produce a fimilar effeftr 

 but in an inferior degree. If the cotton or linen be low 

 plunged into the oxymuriatic acid, and allowed to remain a 

 ihort time, they will become white ; and if they arc th.en. 

 plunged into an alkaline ley, the liquor will again become 

 brown, and lofe its caufticity. 



On faturating either the firft or laft of the alkaline fclu- 

 tions with an acid, a fimilar precipitate is obtained from 

 each, of a dark coloured matter, almoft infolubk in water, 

 l>ut foluble ia cauflis alkali. 



IIcEce. 



