269 Jmpraved Pncefs of Bleaching, 



the coIlefVion of ariimats was difpofed of. Sir Jofeph Banks wa's then abfent from town ; and 

 upon his return he was prevented^ by this circumftiiice, either from purchaiing the animals 

 or acquiring any further information refpeftinjj the foal. I have lately endeavoured to dbtaiit 

 feme intelligence on this behalf among the dealers in animals, but hitherto without fuccefs. 



VII. 



On tht Proems sf Bleacbiug with the Oxygenated Muriatic Acid ; and a Befcription of a new 

 Jjiparaiits for Bleaching Cloths with that Acid dijjolved in Water without the Addition of- 



Alkali. By Theophjlvs Lewis Rupp*. 



T. 



II E arts which fupply the luxuries, conveniences and necefTarles of life, have derived 

 but little advantage fiom pliilofopheis. A view of the hiftory of arts will evince the juftice 

 of this obfervation. In uieclianics, for inftance, we find that the moft important inventions 

 and improvements have been made, not through the rcafonings ofphilofophers, but through 

 the ingenuity of artifts, and not unfrequently by common workmen. The chemift in parti- 

 cular, if we except the pharmaceutical laboratory, has but little claim on the arts : on the 

 contrary, he is indebted to them for the greateft difcoverics, aiKJ a prodigious ?iumber of facb,. 

 which form the bafis of his fcience. In the difcovery of the art of making bread, of the 

 vinous and acetous fermentations, of tanning, of working ores and metals, of making glafs 

 and foap, of the adlion and applications of manures, and in numberlefs other difcovettes of 

 the higheft importance, though they are all chemical proceffes, the chemift has no fhare. 

 But no branch of the ufeful arts is lefs indebted to him than that of changing the colours of 

 fubftances. The art of dyeing has attained a high degree of perfection without the aid of 

 the chemift, who is totally Ignorant of the rationale of many of its procefl'es, and the little he 

 knows of this fubjedl: is of a late date. Tlie proc.efs of dyeing the Turkey red has beea known 

 and pra£l:ifed from time immemorial by the moft uncultivated nations, but its theory is not 

 yet underftood by philofophers. The manufacture of indigo and its application have been 

 long known to the planter and the dyer ; but it is not more than ten years fince a true theory 

 of them has been formed. The art of printing or topical dyeing is of the greateft antiquity ; 

 but the theory of this procefs, and of adjeiStive colours in plain dyeing, was unknown till 

 Mr. Henry developed it in the Memoirs of this Society f. The bleaching or whitening of 

 vegetable fubftances has been long pra£tifed j but the knowledge of its theory could not be 

 antecedent to the xra of pneumatic chemiftry. We might even at this moment have been 

 unacquainted with the caufe of the dettruction of the colouring matter of vegetable fub- 

 ftances, if the difcovery of the oxygenated muriatic acid, and its efFedts on colouring 

 matter, had not pointed it out to us. For this difcovery, and its ineftimable advantages, the 

 arts are indebted to thejuftly celebrated Scheele ; and I am happy to pay this tribute to 

 chemiftry after the mortifying truths which I have ftated above. 



M. Berthollet loft no time in applying the properties of this curious and highly intercft- 

 ing fubftance to the moft important practical ufes. His experiments on bleaching with the 

 oxygenated muriatic acid proved completely fuccefsful, and he did not delay to communi- 



* Manchefter Memoirs, vol. v. part i. \ Manchefler Memoirs, voL iii. 



cate 



