On Bleaching. 57 



attempts hitherto have done no more than dyeing a leaden 

 white, which foon becomes a pale yellow, that requires the 

 joint efforts of oxygen and alkalies to remove, nnifl, on a 

 moment's reflection, be evident to every one. To this caufe 

 may be afcribed the failure of the learned editors of the En- 

 cyclopa?dia Britannica, who were no mean chtmilts. With 

 the acid prepared according to BcrthoUet's mode they dyed 

 yellow, but could not bleach white. 



It is generally agreed, that the muriatic acid is no further 

 ufeful to bleaching than by its power of retaining oxygen in 

 water, and thus conveying it in a ftate fit to aft, more orlefs, 

 on both the external and internal parts of the ftuff to be 

 bleached. Hence it is evident, that the ufe of inch a quan- 

 tity of fait is not only injurious to the celerity of the procefs, 

 but entails an embarralTing expenfe on this method of bleach- 

 ing. However, even this more than triple quantity of fait 

 may have been neceflary to incorporate or retain the requifit6 

 quantity of oxygen to perform the whitening procefs, if the 

 apparatus were not properly adapted. Condenl'ers have been 

 generally ufed, and Mr. O'Reilly propofes (Plate I. fig. I. C.*) 

 an iviprovcd one; but, if duly examined, they will be found 

 not only inefficacious, but highly difadvantageous to the ad- 

 mixture of the oxygen with the water. It is well known how 

 flight the union of oxygen with muriatic acid is; and who- 

 ever will try even this improved condenfer will find an almoft 

 complete feparation of the two gafes before they are brought 

 in contaft with the water. So flightly indeed are they mixed, 

 that the moment the heat and confequent motion is with- 

 drawn from thefe condenfers, that moment the gafes begin to 

 feparate according to their fpecific gravities. At the top will 

 be found tolerably pure oxygen gas, while the bottom con- 

 tains muriatic mixed with fome fulphuric acid gas. This 

 lalt combination is confiderably deterfive, but is alfo fome- 

 what corrofive, and has often damaged goods; a circum- 

 ftance that may l)e avoided by having them previoully wetted 

 in water. It is lefs injurious, however, to cotton than linen 

 goods; and to this is owing probably the great quantity of 

 fulphuric acid ufcd at Manchcllcr, where it is diluted with 

 double its quantity of water; which muft excite (uoh a rapid 

 ebullition, that fome of the fulphuric acid will be carried 

 into the receiver. Snljihuric acid, diluted \\ ith Lj's than its 

 volume of water, will produce the pureit oxymuriatic gas. 

 By ufing condenfers, much of the oxygen too is diflipated 

 through the anti-abforbent tube (if I may fo call it) at the 

 top of the condenfer. Under fuch circumltanccs it is not 



• Sec Philofophical Magazine, vol, X. 



(urprifing 



