366 Socieii/ of Antiquaries. 



after being slightly carbonized and treated with nitric acid, 

 yield this artificial tanning substance ; and that oak-bark, 

 deprived ofits natural tannin in the tanners' pits, by being 

 repeatedly charred or roasted, and as often subjected to 

 nitric acid, is almost toTallv convertible into artificial 

 tannin. Horse-chesnuts arc also transmutablc in a similar 

 degree by the same process. 



The reading of the conclusion of this paper was post- 

 poned till the 6th of February. 



SOCIETY OF ANTiaUAUIES. 



The meetings and adjournments of this society being the 

 same generallvas those of the Royal^ it of course assembled 

 as usual on 



January Qth, the vice-president, sir H. C. Englefield, 

 hart. M. P. in the chair. A drawing of a spear-head found 

 at Gringley Carr's Common, Nottingham, in 1803, was 

 exhibited. This instrument is evidently of Roman origin ; 

 and from the circumstance of its having been so long in the 

 eartli without bemg discoloured or rusted, the learned an- 

 tiquary supposed it to have been made of Corinthian brass. 

 A similar implement is described in the ninth volume of 

 the Archaeologia, and considered as Roman manufacture. 

 With regard to the peculiar qualities and composition of 

 these instruments, a very learned and truly philosophical 

 paper by Dr. G. Pearson, published in the Transactions of 

 the Royal Society for 1 796, will afford the most satisfactory 

 information. From the very accurate chemical analysis of 

 this philosopher, it appears that these Roman instruments, 

 spear-heads and swords, found in various parts of Eng- 

 land, are not brass as conimonly alleged, but an alloy of 

 copper and tin, in the proportion of about 10 parts of the 

 former to one of the latter, the specific gravity of which 

 was about 8* 500. GeoftVoy, indeed, after a number of 

 experiments that might beany thing but chemical, flattered 

 count Caylus bv alleging that they were an alloy of copper 

 and iron ! Such an opinion might have been philosophical 

 in the age of alchemy. From the researches of Dr. Pearson 

 on this subject, a report was made by some French che- 

 mists, in 1801, a translation of which was published in the 

 10th volume, p. 340, of the Philosophical INJagazine. 

 There are many circumstances that render an iutnnate 

 knowledge of this peculiar alloy so much in use with 

 the Romans, highly interesting to the English anti- 

 quary. Doubtless the Romans, when they overran this 

 coujjtrv, taught the aulient Britons how to manufacture 



this 



