for that of Lime, in the Frocess of Bleaching, seg 



Kible a salt that it will readily give way to a few washings ; 

 and were a portion to remain, it would not act as a mordant. 

 The substitution on this account were rational, and I be- 

 lieve the merit of it belongs txclusively to Mr. Duffy of 

 Dublin ; for it will be allowed that the views of Sir H. Davy 

 were complttelv of a different nature. 



From these advantages, however, the bleachers are un- 

 happily excluded, on account of the enormous price of 

 magnesia. Sir H. Davy observes in his Elements, that this 

 iearth may be " easily procured from sea- water, or from the 

 residua! liquor of salt works." The fact is indisputably 

 true, and so well known, that the manufacturers obtain it 

 in this, and, I believe, no other way. Hence, I fear, the 

 obstacle of its price is not the more surmountable from the 

 information conveyed in the above passage; at the same 

 time, not doubting that had Sir H. Davy turned his atten- 

 tion more minutely to the subject, his usual ingenuity 

 would not forsake him. 



In the Elements of Chenrical Philosophy, we read, that 

 at the suggestion of Sir H. Davy, the oxymuriate of mag- 

 nesia Itad been used by Mr. Duffy " iviihin the last few 

 months" for whitening printed calicos. It is with great he- 

 sitation I say, that there must have been some misunder- 

 standing between these jrenilemen \ either party must cer- 

 tainly have misconceived the other's meaning ; and this is 

 not asserted without some foundation in proof. Mr. Duffy 

 informs me that he had used the substance in question, for 

 experiment, as early as December 1810, and largely in the 

 Iieginning of 1811; a period much more distant than *' the 

 last few months." 



Mr. Dufly, far from taking any merit to himself, for ths 

 application of oxymuriate of rhagnesia to clearing, will 

 not even allow any to be attributed to him ; he is anxious 

 that th ' credit of the matter should lie with the person who 

 first conceived the probable success of the process, without 

 taking upon him to decide who the person may be, I shall 

 theretore further the views of Mr. Duffy, and state all I 

 know on the subject. 



When that part ot Dr. Brewster's Edinburgh Encyclo- 

 paedia appeared, which contained the article " Bleaching," 

 I was much amazed and displeased at finding that the wri- 

 ter of that article had assumed to himself the merit of ap- 

 plying the oxymuriate of magnesia, without once having 

 mentioned the name of Sir H. Davy. Anxious to ascer- 

 tain who had the real title, I made an inquiry in Scotland ; 



P 3 lh« 



