On Bleaching. , 35 



they were sufficiently white for every purpose except print- 

 ing. More tlian 5000 pieces have been bleached at uiy 

 works (at White House, near Belfast) in the same uian.ner, 

 without any appearance whatever of buff, as before men- 

 tioned ; only half the usual quantity of oxygenated muriatic 

 acid has been used; the receiver afforduig sufficient for 

 seven to eight parcels of calicoes, which before was only 

 equal to three or four — So much less was required to bruig 

 UiG liquor in the kievc to its usual stienffth, (which was 

 ascertained by the test of solution of indigo hi sulphuric 

 acid,) and so little had the liquor been exliausted by oxidai- 

 ing the iron in the cloth. Sec. in lieu of acting on the co- 

 louring part. 



It has been long known, and as long lamented by the 

 calico printers, that yellow stains have appeared after the 

 printed pieces have been dyed, and that such stains cannot 

 be bleached out without reducing and materially injuring 

 the colours. Prior to the commencement of the process I 

 have described (I mean, the use of sours previous to the 

 cloth being exposed to the oxygen of the atmosphere, by 

 being spread on the field, or inunersed in the oxygenated 

 iimrialic acid) a considerable quantity of calicoes had those 

 stains ; but I am happy to state, that on dyeing in the same 

 parcels, and the same coppers, pieces of the old process, and 

 pieces of the new, the latter were perfectly clear, and the 

 iirst stained. 



This defect continucxl as long as any of the old bleach 

 remained, but with them stains entirely disappeared. The 

 new bleach were perfectly clear, by lying two or three days 

 on the grass, after dyeing : the old not in as many weeks. 



It is unnecessary U) say to men of practice and science, 

 that the same process of bleaching iii applicable to linen and 

 to cotton, linen re(juiring only a stronger process and more 

 time, or that iron oxidated and iron moulds are the same; 

 and that the quality of cloth is in consequence injured, as 

 they are generated bv combustion in consequence of the 

 union of oxygen gas; hence the quantity of bucks (rotten., 

 linens) and iTnens also resuming a yellow hue after being 

 bleached and exposed to the air, wiiieh acts on the iron re- 

 maining in the cloth. 



The eye of the scientific mind will discover at the first 

 glance, that a solution of sulphuric acid will take up or dis- 

 solve iron in the cloth, and reudi.r it luiscible, or s jjublc in 

 water, it ajjplied previous to its becoming mi oxide. 



Let us ihcu look at what the bleacher lins to contend 



with and to eradicate: and it will be found he ha^ the re^in 



wr colouring matter of the flax: or cotton, iron, and the 



C <2 v.eavci'3 



