Jin Ejpiy on Bleaching. 299 



well diffolved. Then add about a pound or a pound and a 

 half of white foap, fhaved down or cut into thin dices, to 

 every ten pounds weight of the refiduum of the lichen. Con- 

 tinue the boiling until the white foap is fully dififolved. Then 

 pafs the foapy folution through a hair fieve or hair bag. Let 

 the foap pan then be cleaned out, and the foapy folution re- 

 turned to the pan, to be boiled to the confidence neceflary. 

 A kind of foap very (imilar to this may be made from fea 

 weed, as well as from feveral other articles. Of this and of 

 other matters highly important to calico printers, a more full 

 and detailed account will be given in a future publication. 

 When gum from the lichen is to be employed for making 

 ink, manufacturing and ttaining paper, and for (lifTening 

 filks, crapes, and gauzes, it mould be extracted from the 

 lichen without employing any alkaline falts, continuing the 

 boiling or digeftiot) longer, and with a moderate degree of 

 heat, in which cafe the gummy extract will be nearly co- 

 lourlefs. When volatile alkali is ufed, the boiler fhould be 

 of iron, as volatile alkali acls on copper. 



[We have not yet learnt the ifliie of the negotiation be- 

 tween Lord Dundonald and the calico printers in Scotland; 

 but we underftand his Iordfhip has taken out a patent for his 

 invention for England.] 



XLVIIT. An Effay on Bleaching; with the Defcription of a 

 new Method of Bleaching by Steam according to the Pro- 

 cess of C. Ciiaptal ; and on its application to the Arts. 

 By R. O'Reilly, of the Academy of Bologna, Member 

 of the Lycawm of the Arts, £#j. 



[Concluded from p. 264.] 



Befloration of Booh, and whitening Prints. 



X HE oxygenated muriatic acid has the property of 

 whitening paper without altering its texture. Chaptal iirft 

 made known the procefs for this purpofe, which is valuable 

 for reftoring old books, and prints ftained with fmoke. His 

 procefs ha* even been executed, with aftonifhing fuccefs, by 

 Vialard and Heudier: when the leaves are not too much de- 

 compofed by time, the oxygenated liquor or the acid gas is 

 employed. Immerfiou in the liquor is to be preferred, as 

 being more- expeditious. 



[The author here gives C. Chaptal's procefs, for which fee 

 Philofophical Magazine, Vol. II. p. 28. Inftead, however, 



6 of 



