8^ Observations on the Processes of Tanning. 



ing any peculiar connection. This system he attributes 

 to Dr. Thomson, author ot" a very excellent article on che- 

 mistry, in the Supplement to the Encyclopaedia Britannica, 

 and of a separate elementary w ork on the same subject. 

 You remark in a note that this opinion was before published 

 in Gren's Chemistry. 



Long before the appearance of the latter work in England, 

 and I believe before the pi\b!ication of that shorter and 

 more comprehensive system, which has been translated, and 

 which vou quote, tl\c same opinion was published in a work 

 entitled " Essays by a Society of Gentlemen at Exeter;" 

 and those essavsj which relate to philosophical subjects, 

 were reprinted in tliis part of Britain, by what authority I am 

 not infoniied. In one of these essays the peculiar and di- 

 stinguishing properties of light and heat are pointed out. 

 The author attempts to show that thcv are distinct bodies, 

 by a variety of facts, and that, instead of being related, they 

 are apparently aritagonizing principles, repelling each other. 

 He traces the principle of light, as it forms an mgredicnt in 

 many difVerent bodies, not only in chemical combination, 

 but in a looser union, where its separation takes place with- 

 out decomposition. 



If this opinion be then established, that author must have 

 the prior claim ; and it is remarkable that, in the Encyclo- 

 pcedia, it is attributed to Dr. Parr of Exeter, though the 

 name is omitted in Dr. Thomson's separate work. But with 

 this conjecture I have no business: my wieh is. only to state 

 the circumstances. 



As I have paid some attention to this subject, I may 

 trouble you with some further remarks on it, should you 

 approve of the communication. I will now only intrude 

 further, by requesting a place for this letter in your next ; 

 and am vour sincere friend and well wisher, 



T. R. O. 



XIV. Observations on. the Processes of Tanning. 

 By Mr. Davy*. 



I. On the Preparation of Skin for Taniiing, 



In all the processes for forming leather, the skins arc de- 

 pilated, and freed from flesh and extraneous matter before 

 they are submitted to the action of the tanning lixivium4 

 In some cases, when large skins are employed, a slight 



■"■'•*• ^Ploih The Journals of the Royal Instkution of Qreat Britain. 



degree 



