I 



On an nrl'ifiaal tamung Sulstance. 181 



examined, T shall mention various kinds of wood, copal, 

 amber, and wax, all of which, when reduced to coal by 

 sulphuric acid, yielded similar products, by subsequent 

 treatment with nitric acid. 



But this substance may likewise be artificially produced 

 without the help of nitric acid, akhough in a less propor- 

 tion, as well as with some slight variations in its charac- 

 teristic properties ; for, as I have already observed, when 

 any of the resins or gum resins (such as common resin, 

 elemi, assafoetida. Sec.) have been long digested with sul- 

 phuric acid so as to assume the appearance and general 

 characters of coal, if afterwards they are digested with al- 

 cohol, a portion is dissolved, and a dark brown solution is 

 formed which by evaporation yields a mass soluble in water 

 as well as in alcohol, and which precipitates gelatine, ace- 

 tite of lead, and muriate of tin, but produces only a very 

 slight effect on oxysulphate of iron. This substance, there- 

 fore, which may thus be separated by alcohol from the coal 

 formed from resinous bodies by sulphuric acid, evidently 

 contains some of the tanning matter, which has been pro- 

 duced during the carbonization of those substances. 



A natural process very similar to this I much suspect 

 takes place in some cases where peat is formed ; I say in 

 some cases, because the production of tanning matter does 

 not seem to be absolutely a necessary consequence attend- 

 ant on the formation of peat ; for in many places where 

 the latter abounds the fonner cannot be detected, whilst 

 in others it is very abundant, and acts powerfully on 

 animal bodies which have accidentally been exposed to its 

 effects. 



There are manv facts of this kind upon record, such as 

 the account of the bodies of the man and woman pveserved 

 in the moors near the woodlands in Derbyshire, Ind also of 

 the woman found in the morass at Axhohi), in Lincoln- 

 shire*. Now I am much inclined to believe, that the 

 tanning substance which so much abounds in these and 

 some other peat moors, did not oriiiinally exist in the vt- 

 cetable substances from which the peat has been produced, 

 but that it has been and continues to be progres;-ively form- 

 ed (under certain favourable circumstances) during the 

 gradual carbonization and conveision of the vegetable mat- 

 ter into peat. 



§111. 



In most of the former paper.-, whiefi I have had the ho- 



• Phil. Trans, vol. iixviii, p. -11:). Ibid Virl iliv.p. 5T1. 



M 3 nour 



