392 On the quantities of tanmng'princj pie and 



The fpirituous infufion, according to Halkr, has more efFeft than the aqueotis iijfu. 

 fioii, and the latter more the decoftion and cxtrafl. It is to be fuppofed then .thatthc 

 virtue of the plant refides in the volatile parts which boiling evaporates. • 



At the article of the black, hellebore (helleborus viridis, L.) Ilaller alfo affirms, 

 that that plant is ufed to poifon arrows. He quotes Monardus, who hientions of a hen 

 which died, after a fibre of black hellebore had been pafTed through her cpmb. It is diffi - 

 cult, however, to afcribe fo deleterious an aftion to that hellebore ; for ever fince the 

 time of Colwnella the root has beea ufed to make fetons for fiieep, which tiic) 

 ufually pafs through the fkin of the neck. It produces fuppuration. 



With regard to the aconites, I find in Haller's works, relative _to that kind which 

 Linne calls aconitum cammarum, that its juice having cafually, and in a very fmall 

 quantity, entered a wound, the accident was followed by cardialgia, fainting, Avelling, 

 and at length a gangrene. 



It appears from thefe fafts, that the three plants I have mentioned, particularly the 

 veratrum, were ufed by the ancient inhabitants of Europe to poifon their arrows, and 

 that the ufe of fire-arms alone has abolilhed that of the poifon, ufed by the Spaniards as 

 late as the lafl century. 



III. 



Experiments to determine the quantity of tanning principle and Gallic acid, contained in 

 the Barks of various Trees. By George Biggin, Efq.* 



X HE bark of trees contains the aftringent principle called gallic acid, and, alfo that 

 principle which has a peculiar affinity to the matter of fkin, and which, from the ufe to 

 which it is applied, is called the tanning principle. But in the prefent mode of tanning, 

 bark is applied in mafs to the (kins; confequently both principles are applied. It re- 

 mains for examination whether both principles are ufeful in the procefs of tanning; for 

 if they are not both ufeful, probably one is detrimental. 



To a Nobleman whofe zeal on every occafion by which the fciences or arts may re- 

 ceive illuflration or improvement, is eminently confpicuous, and to whofe pub! it 

 energy, as well as private friendfhip, I feel myfelf much indebted, to his Grace the Duke 

 of Bedford I owe the means of profecuting fome experiments on this fubjefft. His 

 Grace, by collefting a variety of barks at Woburn, gave me an opportunity of making 



* Philof. Tranf. 1799. p. 299. 



feme 



