' [ 226 J 



XLI. On the Substitution of the Oxijmuriate of Magnesia 

 for that of Lime, in the Process of Bleaching, &c. By 

 M. Donovan. 



To Mr. Tilloch. 



Sir, JL he readers of your Magazine are already in pos- 

 session of the facts stated by Dr. Ogilby to the Kirwanian 

 Society, relating to the effects of oxymuriate of linie in 

 bleaching. I was present at the reading of the paper, and 

 with many others examined fhe specimens of linen which 

 had suiTered imniersion in the soUitiwns of nuiriatc of lime. 

 These specimens, as far as I conld judge, appeared to be 

 perfectly sound : the rest of the members also declared 

 themselves satisfied that the linen had not been perceptibly 

 injured. 



Sir H. Davy, in his lectures delivered in Dublin 1810, 

 observed that he had sufficient reason to believe that mu- 

 riate of lime does a material injury to the linen fabric. In 

 the " Elements of Chemical Philosophy," SirH. states that 

 linen boiled in a strong solution of muriate of lime is " con- 

 siderably weakened." Lately, also, it has been positively 

 asserted that the injury done by muriate of lime amounts 

 to absolute rottenness. On the other hand, Dr. Ogilby and 

 some gentlemen who have repeated these experiments still 

 maintain that the linen in this operation suffers nothing. 



Somewhat amazed at such extraordinary and unqualified 

 contradictions, I was resolved, merely for my own satisfac- 

 tion, to attempt an experiment on the subject. My results 

 I communicated to Dr. Ogilby ; and at his instance, as 

 there had been some difl'erence in our methods, I ventured 

 to make public whatever I had ascertained. 



I first prepared a perfectly neutral muriate of lime : the 

 solution was of such a strength, that it remained fluid du- 

 ring the day-time only, but as the coolness of evening ad- 

 vanced it deposited a few crystals. In this saturated solu- 

 tion I immersed a piece of sound linen, and suffered it to 

 remain for 4S hours ; at the end of which period I washed 

 and dried it; but found it, as well as I could judge, as 

 sound as before. 



I then look another piece of the same linen, and boiled 

 it for an hour in a new portion of the same concentrated 

 solution of muriate of lime. At the end of this period it 

 was allowed to C(K)1 ; the muriate had become a solid white 

 massj of considerable hardness. As much water was poured 



on 



