ARTIFICIAL TAN. , 327 



VI. 



Firft Communication on an artificial Tan prepared fron Coal, 

 chared Wood, refinous Subjlanccs, IfC. Abridged from the 

 Original of Charles Hatchett, Efq. F. R. S.* 



IR. HATCHETT firft notices, that the natural tannin Firft difcovery 

 was firft extracted from the matters which contain it, by M.Tegu^and 

 Mr. Deyeux, who confidered it as a Ipecies of refin ; tbatDeyeux. 

 Mr. Seguin firft di (covered it to be the fubftanee which 

 in the procefs of tanning renders animal fkins infallible in 

 water, and imputrefcible; but that Mr. Chenevix alone had 

 noticed the effect of heat in giving coffee berries the power 

 in decoction of precipitating gelaten. He then ftates, that Refult of ex- 

 his experiments on lac, and fome of the refms having thewed foi"[-^ fj!£ 

 him the powerful action of nitric acid on fuch fubftances, in- induced others 

 duced him to try its efFed on afplialtum and jet; thefe with °"/S£ a1 ^ 

 it formed a dark brown folution, and a precipitate, which by nitric acid. 

 digcftion in another portion of the acid became diholvec), 

 and on evaporation produced a yellow vifcid fubftanee foluble 

 in water and alcohol, and perfectly fimilar to that obtained 

 by fimilar means from the reiins, excepting that when burned 

 it had the colour of the fat oils. This refult led to the fuppofi- 

 lion, that the dark brown folution was of the carbonaceous 



As native magnefian earth would doubtlefs be of great uCe to the 

 potteries of this country, it is a pleafing con fi deration, that it is 

 extremely probable it may be found in England, as well as on the 

 Continent ; for not only fteatites and other magnefian ftones have 

 already been difcovered here, but that fait, which it is M. Giobert's 

 principal object to manufacture, is the natural produce of this 

 country, and therefore the neighbourhood of Epfom; which gives 

 it its name, may well be fufpecled of containing beds of an earth 

 fimilar to that of Baudiflero. 



There is alfo fome reafon to fuppofe, that this earth may be one 

 of thofe ingredients in china-ware, which the Chinde endeavour 

 to keep fecret; indeed it is hardly probable they fliould be ignorant 

 of its ufe, in a country, where the fuieft eaithern-ware. has heen 

 manufactured in the greater! perfection., from period., antecedent 

 to the dates of the authenticated hiftory of Europe, and where of 

 'courfe experiments relative to the compofition of this article, muit 

 have been varied to the greateft extent. — B. 



* Ph'iiof. Tranf. 1805. 



matter 



