Linen and Cotton Cloth. 197 



upon Mr. DiifFy, when I found my statements so coarsely 

 attacked ; and he assured me, and gave nie authority to 

 state, that in the process of what is properly called bleaching, 

 he had never given his approbation of the employment of 

 the oxynjiiriate of magnesia; it was only in a particular 

 operation in calico-printing, called c/eanrto^, that he could 

 see any reason for using this substance; and it was not 

 because muriate of lime destroyed the vegetable fibre that 

 he was led to the use of it, but upon different principles, 

 not one of which the Professor even hinted at in any of 

 Ijis lectures before Mr. Duffy had sent a communication to 

 him upon the subject. It is also with the full permission 

 of Mr. Duffy, thai I state it as his opinion, that the oxy- 

 tnuriate of lime can be employed in bleaching with perfect 

 safety ; and the fact is, that in his preparatory process of 

 whiienino; the cottons he still uses iliis salt. He says, indeed, 

 that if anyone will give him magnesia at one penny -^^.x 

 pound, he will then prefer the magnesian salt; but not at all 

 in consequence of Sir Humphry's opinion that the salt of 

 JiiTie is iujurious to the texture of the cloth, but for other 

 reasons, and principally because magnesia has much less 

 action upon the dyed colours than lime has; — a subject 

 upon which the Pnjfessor did not give the slightest hint at 

 the time he made his proposal. If Mr. Duffy, in a polite 

 letter to Sir Humphry, gave him credit as the suggester of 

 such an improvement, it can only be inferred that Mr. 

 Duffy has been extremely liberal, and has acted with much 

 self-denial ; for I am fully convinced that he himself has 

 the whole credit of the improvement; for unless mentioning 

 the mere name of a substance can be construed into a hint 

 to the calico-printer to apply it to a particular process, Sir 

 Humphry has no claim whatsoever to be considered as the 

 proposer*. 



That iMr. Duffy has not at any time approved of the 

 rejection of oxymuriate of lime by the bleacher, the fol- 

 lowing passage in his letter to Sir Humphry evinces: "The 

 introduction of the oxymuriate of lime by Mr. Tennant 



• " la searclilnfj for a substance which possesses none of those perniciou* 

 quaiiliee, (alliiiiing to the action ot lime upon tl'.e dyes,') we have lound that 

 the oxymuriute ut magnesia in every respect answers m the most complete 

 iiiannur, ni;t only for itcaniri tlie v/hite ground of the goods, Init also in 

 prcf.ervinjj the colours of the same shade which they were originally. 



" Of all ihe earths which are partially loluble in water, magnesia possessei 

 the property ol changing colours least, the alteration made by it upon paper 

 ftained wiili litmils Leing scarcely perceptible. It is therefore peculiarly 

 £tted, when united with oxygen, for the purpose of clearing the itain froni 

 the wliiie of priutcU Koodt." Kdmiurnh Cydopcedia, article Bltachiag, 



N 3 hai 



