A Substitute for Oak Bark in Tanning , 423 
homogeneous in all their parts, and are not so easily 
broken. 
Besides the advantages which this invention on the 
first view exhibits, it offers others which may be of great 
utility in our arts and manufactures. 
1st, In the large manufactories of mirrors the ornaments 
in general are in a very bad taste and miserably executed^, 
because the carvers are very ill paid. If this new me- 
thod be adopted, sculptors would pay more attention to 
their first work : they would mould their ornaments in 
plaster or in sulphur, then take a multitude of copies 
with the greatest facility, and these ornaments would add 
to the value of our furniture. 
2d, Inlayers would make much more elegant works by 
employing pastes of different coloured woods, which 
might be managed with greater ease than the thin pieces 
of coloured boards which they employ. I am now en- 
gaged with some experiments on this subject. My intern 
tion is to make small tablets to imitate mosaic. I shall 
communicate the result to the public as soon as my expe^ 
riments are terminated. 
No. 83. 
A Memoir concerning several indigenous Plants , which 
maij serve as a Substitute for Oak Bark , and for cer- 
tain foreign Articles in the Tanning of Leather 
THE object of this memoir is to show how the de- 
struction of trees, and particularly of oak-trees, which 
are so valuable, may in great part be prevented. A 
great consumption of them is caused by the tanneries. 
* Tilloch, vol. 17, p. 140. From the Transactions of the Royal Society of Ber- 
lin t y ol. 10 
