TANNING MATTER, &C. 97 



An inquiry into the nature and formation of coal was, Expei'iments, 

 my first object when I discovered the artificial tanning fjciai substance 

 substance, and considering the importance of the latter, havingthecha- 

 it will not appear surprising, that it should immediately ^^-'^" °* J^"" 

 have engaged the principal part of my attention. 



In addition to the experiments which have been related 

 in the three Papers upon this subject, I intended to have 

 decomposed the different varieties, to have compared 

 their gases and other products with those of the natural 

 substance, called Tannin, and especially to have endea- 

 voured to discover more economical methods of obtaining 

 the artificial product; for, exclusive of speculative science, 

 this appears to be an object of consequence, not only 

 respecting that useful and valuable branch of manufac- 

 ture, to which it immediately relates, but also as the 

 means of preventing, or at least of diminishing, the pre- 

 mature destruction of timber in a country, where, on 

 account of its population, as well as on account of its 

 maritime position, every economy in such an article 

 should be most rigidly observed. 



But for the present, I intend to relinquish this subject 

 to such as may consider it worthy of attention ; whilst^ 



one time apparently insurmountable obstacle to the Huttonian of 

 Plutonian theory, and if they do not solve the grand geological 

 problem, they must even, in an insulated point of view, be- allowed 

 to have opened a new and unexplored field of research in chemistry 

 as well a? in geology. 



In the 8th section of this valuable Paper, the author has given an 

 account of some experiments made on leather, horn, and fir sawdust, 

 from which he obtained coal which burned with flame, and which 

 apparently resembled some of the mineral coals. In 6ne case also, 

 he obtained a substance, which In external characters appeared 

 somewhat similar to the mixture of asphaltum and resin found at 

 Bovcy, to which I have given the name of Retin-a^phaltum. These 

 experiments Sir James Hall intends to resume, andltlsmy ear- 

 nest wish that he would do so ; for although I am strongly inclined 

 to believe that the mineral coals have generally, If not always, beea 

 formed by some humid process, yet it Is Impossible to foresee the 

 results which may be obtained from animal and vegetable bodies 

 subjected to the effects of heat modified by compression, as the prin- 

 ciples o^ these bodies may be acted upon, and may be made to re- 

 act on each other, under circumstances which until now have not 

 been imagined. 



Vol. XV.— Oct. 1806. O ' n« 



